What ORMs have taught me: just learn SQL (2014)(wozniak.ca) |
What ORMs have taught me: just learn SQL (2014)(wozniak.ca) |
A now defunct site discussing why ORM is a poor map.
Admittedly, this doesn't end up being great, but it seems hard to solve this well in other ways, as much as I wish I could write SQL and get types for free.
Every time I tried to do a project without an ORM, using only raw SQL, I inevitably ran into:
- serialization/deserialization boilerplate. Like, having to manually map values returned by the DB library to object (or named tuple, or structure) properties
- poor code reuse, having multiple very similar queries that have just one small difference
- extra pain in changing DB schema. Adding a field requires to go and manually edit many queries
Anti-ORM crowd never gives a good answer to these issues.
Instead, they push strawman attacks like "oh, you only use ORM, because you can't write raw SQL". I can absolutely assure you that this is not the case. Every time I use an ORM (SQLAlchemy mostly, the one mentioned in the article) I am 100% sure what SQL do I want it to produce and what SQL will a particular ORM invocation produce.
Can the OP expand on why this is? Just curious.
For example, the ASP.NET Razor syntax allows HTML and C# code to be interspersed surprisingly freely:
<ul>
@foreach (var user in Model.Users)
{
<li>@user.Name</li>
}
</ul>
Just picture the same kind of thing, but with SQL expressions freely interspersed with the programming language.Just like how Cargo, NuGet, NPM, etc... can import packages and/or how you can cross-reference projects in build systems, web apps should be able to reference a database schema project directly, importing the SQL definitions without any explicit "mapping". If the SQL changes, the type changes, and the build system picks that up automatically without any additional manual steps.
.NET with EF Core is almost there, and I've seen some half-hearted attempts in various languages over the years, but it's like the industry has an allergy to the concept.
Ur/Web is probably the closest to the idealised concept, and I think that's what I read years ago that put the dream in my mind: https://dl.acm.org/cms/attachment/feb131ab-37e1-4638-be17-ab...
There is nothing that an ORM can do to help with this sort of problem without reaching for the obvious escape hatch of arbitrary command text execution. The ability to map the tables to objects in my programming environment is a distracting clown show for this specific problem. What really matters is understanding the provider and its techniques for bulk loading records. No ORM will ever be able to touch these provider capabilities on their "happy" paths. At best you'll wind up using the ORM and a bunch of provider-specific SQL anyways.
ORMs for schema management is a stronger argument, but only in cases where the codebase/service has complete ownership over each respective database. Any kind of heterogenous workload says that ORM for schema management is a potential nightmare unless you do something like create a project that is only for migrating the schema, at which point I'd argue you could just maintain a source controlled folder of sql/shell scripts.
So I think the ORM debate could be over
postgresql is a beast
NoSQL for operational data storage is more efficient and cost effective.
ORMs were a regression test that exposed unnecessary complexity.
That's important. Because now days it's trivial for LLMs to translate ORM to SQL and vice-versa with ~100% accuracy. I haven't written any raw SQL (only Active Record) in about two years, and the odd time I blunder with AR and create an n+1 I find out about it via error tracking (e.g. Sentry) a few minutes later and fix it. No biggie.
There's also an additional layer of protection in that using AI on the codebase can spot SQL blunders incidentally (i.e. you ask about X, and the AI does X but also says "Not asked, but flagging for your attention: problem with SQL on line 256 etc.."
Relational databases are incredibly flexible even if you have a NoSQL mindset, you can do data modelling like that in Postgres too with jsonb data types.
The problem with "schema change", and I did this for decades, is that it's always a massive blocker. In some companies the data architects had to approve and implement schema changes. You could wait days for that. NoSQL allows you to modify the document surface in mostly non-breaking change ways OR it's easier to version your APIs to handle different document versions.
Simple CRUD: Any data store is fine. Complex multiple bounded contexts: Choose the appropriate data store for each bounded context accordingly.
My point was no one should be reaching for a relational database or starting with an ERD to build a system. Document behaviors. Model the system. Let the system decide what data storage it requires.
Counterpoint: force the system to use an RDBMS to store data in properly normalized schema, because it’s the only thing guaranteeing that the data will continue to exist as you expect.
Schema management is the single worst part of deployments.
If I build on DynamoDB vs RDS I can save 10x.
I would challenge you to look at event driven architectures, CQRS, event sourcing, and how to implement and leverage read models.
It will expand your architecture toolkit.
I also note that in their FAQs [2], they erroneously state:
"MongoDB’s data modeling best practice suggests storing related data together in a single document using a variety of data types, including arrays and embedded documents. So, a lot of the time, ACID is not required as it is a single-document transaction."
Whether or not you're operating on a single document has nothing to do with its ability to meet durability guarantees (or consistency, for that matter).
NoSQL databases make tradeoffs for performance, and making the lives of devs easier in the short term. That's fine, if and only if you accept what you're losing, and document it for others who may not be aware. If at any point you can have your application get a write ack'd and subsequently lose the write, you do not have a durable data store, and you do not have ACID compliance. Whether that's the fault of the DBMS, the operating system (Postgres' fsyncgate), or hardware (drives lying to the OS about the write's durability without the benefit of PLP) is irrelevant – you have to understand the entire chain to make those guarantees, or at the very least, trust your upstream provider to have understood it for you and made the correct decisions.
0: https://www.mongodb.com/docs/manual/core/journaling/
1: https://dev.mysql.com/doc/refman/8.4/en/innodb-parameters.ht...
2: https://www.mongodb.com/resources/products/capabilities/acid...
ORMs that try to paper over all the differences fail miserably. They become super complicated and generally produce crap SQL.
ORMs also tend to oversimplify database design. They are just tables with primary keys, right? Who needs indices? Who needs to think about collation? God forbid anyone mentions physical organisation of the data!
Having said this, I do use a very small subset of SQLAlchemy (the bits I understand) in data pipelines.
I make use of table-valued db functions (IMO the most underrated feature of relational DBs) to define virtual relations/tables. I implement a set of CRUD db functions per entity. Then, on the app side, I define (or generate) DTO types representing these virtual relations. Finally, I use a custom ORM I wrote myself, which defines a general and consistent storage API, to talk to the db functions, using the DTO types.
The advantages of this approach are numerous, some include:
- I have full control of the SQL that goes into constructing the virtual table, I can leverage all the goodness of SQL here. I can even define multiple virtual relations per physical table, or read-only relations, etc, all by implementing the appropriate sets of CRUD db functions
- On the ORM side, I have all the goodness of static typing, a consistent API for all CRUD methods, a full fluent query DSL, etc
- Since, unlike tables or views, db functions can be passed arguments, i am able to layey all kinds of goodness on top of the basic CRUD actions, like audit info passing, custom upsert strategies, some level of record-based authorization, etc
But this architecture does require you to know and write SQL. IMO the value of ORMs do not lie in avoiding SQL; it lies in the capability to express consistent SQL at a higher level of abstraction, but you still need to understand your SQL.
PS: I still exported the table before deploying this fyi.
I stopped using ORMs around 2008 because they made the easy problems easier and the hard problems harder. I wanted to just write SQL and exploit all the power the DBMS has to offer instead of fighting with an abstraction layer, so I created Pyranid in 2015 and keep it actively updated.
We have lots of experience with ORMs based on dynamic languages (i.e. Objective-C and Ruby) and if not careful, you can indeed go sideways pretty quickly.
Recently, we've been using https://ash-hq.org. It tries to solve the same problems as an ORM, but using a pure functional language (Elixir). You are using structs instead of objects, so it can feel very close to using raw dictionaries/hashes. It also makes it super easy to drop down to raw sql, while maintaining that struct interface at the top.
While it does take some getting used to (especially coming from a dynamic, OO language), I'm liking this alternative a lot!
I haven’t personally had third-party ORM frameworks succinctly encourage synchronization and help me build against long-term divergence of data models across the stack. “Make it easy to do the right thing and hard to do the wrong thing” still leaves a lot of room for ‘gotchas’ as apps evolve over time.
Finally, I don’t understand the aversion in learning even a bit of sql. As topics go, it’s a very good (maybe even the best, if I were being provocative) effort:payoff ratio. Not sure I’d call myself a sql expert, but am always pleasantly surprised how much functionality is within reach by knowing even the very basics of sql.
For me I find it's an excellent step up from a plain SQL query builder (with an API such as `select(Foo).join(bar)`) as it lets me both effortlessly perform projections (one can write `(\e -> (e.foo, e.bar) <$> someQuery` to take a query producing rows of `E` and turn it into rows of 2-tuples built from two projected fields.
I wrote a bit about my Rust rewrite here: https://bensimms.moe/postgres-lateral-makes-quite-a-good-dsl...
Implying I use an ORM because I don't know SQL... I've reverse engineered embedded databases and written directly to the .dat files on production systems that deal with HIPAA data. I'm pretty sure I know SQL better than most people on HN. I still prefer an ORM.
Why? Because with my ORM, I can code gen faster than you can vibe code. I can build on top of the abstraction layer. The data model in the ORM is the M in MVC. The backend could be a SQL database, a file system, a REST service, that part is irrelevant. The M is the same, regardless of the backing store. View and Controller code still works.
I find most people who are anti-ORM are kinda junior and trying to flex their power to write SQL scripts as if it is impressive. That's why there's always this weird implying that ORM users don't know SQL.
These are simply tools. The only wrong opinion is to believe that there’s a strict superiority of one over another. However, the content of this and other blogs can help people make informed decisions on when to reach for each tool.
The generator takes a single specification and produces everything needed for the server, client, and databases (SQLite, Oracle, in-memory, etc.) to stay perfectly in sync.
It has worked really well for us and has been a huge productivity boost.
The idea is that you like SQL, but it gets repetitive writing joins and accessor code. I had always hoped it would catch on as a pattern: no boilerplate, automatic mapping to objects in your code of any query (whether generated by the ORM or passed in as a raw query) and easy to override/dynamically build bits of the query as you pass the object around.
EDIT: oh wait looks like I never got around to implementing the ability to use custom classes :) this is still in the to do section:
come up with a good "mix in" style to cast the objects returned from the iterator to a new class for implementing custom functionality (that one would normally include as part of the "boilerplate" class)
- "the pernicious use of foreign keys [...] links between classes are [...] foreign keys" ==> that just sounds like schema normalization, which is usually a good thing?
- "bending over backwards [...] to generate SQL that runs efficiently" ==> the huge majority of ORM-driven queries are "select * from table where id in ..."; for the queries that are more complicated than that, then yes use SQL! That's allowed!
Folks who dislike ORMs seem to have this false dichotomy that "the ORM _must_ be used for all queries", which is a self-imposed/unpractical restriction.
- "dual schema dangers" ==> he's exactly right that database should own the schema definition, but then just codegen the entities from the db schema? That's your singular source of truth, no drift. You can do this with Hibernate, ActiveRecord, Joist, many ORMs.
- "Identities" ==> ironically I think ORMs (that use the unit of work pattern) actually have net-better DX here b/c you can hook up a graph of entities with just references.
I.e. hook up a book to its author w/o knowing their ids yet, which explicitly avoids the annoyance he mentions of doing a partial commit/going to the db to figure out "what value should I INSERT into in the book.author_id column?" (but my author is new) in the middle of your business logic that just wants to "create books".
- transactions ==> agreed that "transactions via annotations" ala JPA/Hibernate are terrible, but afaiu all "internet scale" apps these days do reads outside of transactions, and just use op-locking during the singular flush/commit step to the db.
Disclaimer I am sure I won't change anyone's minds :-)
Edit: in the HN comments, we're debating "the best way to generate SQL", which is fine, but imo it overlooks the biggest value for ORMs: enforcing business invariants.
I.e. yes a simple INSERT is trivial is write, "why have the ORM to that!", but are you going to enforce the same business logic in the 10 places you do `INSERT authors` in your codebase? And if the answer is "I write an single `insertAuthor` abstraction to enforce this" then you're half-way to writing an adhoc half-specified, bug-riddled version of what a reactive ORM like Joist will do for you. [2] :-)
> ...(although things like Postgres’ hstore can help)...
Back when this blog post was written, this advice would have been reasonable. Today, I don't know anyone reaching for hstore since the more featureful json support was added.
I'm talking about my experience, not generalizing to all DBAs of course. And of course ORMs introduced performance issues, etc.
ORMs are just a layer of abstraction. Like any abstraction, they make some tradeoffs that can get you into some sticky situations like inefficient queries mentioned in the article.
But, if you understand the tradeoffs, you can use them for what they're good for (standardization & simplification & in-codebase schema definitions & so on) and usually drop down to SQL whenever there's a particularly necessary case.
We do programmers always need a library?
Program the damn thing.
Can anyone that has used ActiveRecord share their opinion?
Even when using other languages, I just pine for LINQ/EF Core. It's truly the best ORM in my opinion. Also, even if one does not want to use the LINQ or the Query syntax (I forgot what it was called), the ability to execute SQL is also still a game changer.
It's like people can't just let go.
users = User.find_by_sql(<<~SQL)
SELECT users.*,
COUNT(posts.id) AS posts_count
FROM users
LEFT JOIN posts ON posts.user_id = users.id
GROUP BY users.id
HAVING COUNT(posts.id) > 10
SQL
users.first.posts_count
# => 17This is exactly why I hate ORMs. As I always put it "ORMs make the easy stuff slightly easier, and they make the harder stuff way harder".
If you're just using an OEM for the "select * from table where ID in ...", then you're saving practically nothing by using an ORM - just learn to write SQL, because as you put it, you're going to have to use it anyway for places where it falls over. There are lighter weight options that do basic stuff like transaction management and binding result sets to object properties that are much less of a PITA than ORMs.
In practice I've seen people try to use the ORM features first for places that need complicated SQL (which is a reasonable assumption), only to waste a boatload of time before concluding the ORM makes stuff harder.
Query builders like these are my personal favorite from a productivity perspective! The point of a query builder is to dynamically build SQL statements that have many subtle variations (do we want to filter by EmailID or PhoneID here? What about a subquery? Did the caller want all results, or just results where $field=X?). They're basically one level above string templating for SQL generation, and often have niceties around ser/de and transaction management as you mentioned.
Because they are primarily about query generation, it feels _very_ natural to pop off the hood and write raw queries directly when necessary. You can usually use the transaction management and ser/de parts with raw queries, too.
My personal favorite in this field is knex.js.
I.e. regardless of how easy it is to write `INSERT authors (...) VALUES (...)`, with an appropriately cute/ergonomic query builder to bind the variables/POJOs ... where does your business logic actually go?
Whenever you insert an author, are you always enforcing the same validation logic? Whenever you update a book, are you always updating the derived fields that need updated?
Getting the business rules right is "the actual hard stuff" imo, and nothing I've seen a query builder help with; it's always left as an exercise to the reader to reinvent their "business logic wrapped around POJOs" adhoc in their codebase.
You’re saving hundreds of lines of repetitive boilerplate code. Do you enjoy writing something like
users = [
User(name=name, color=color)
for name, color
in db.query("SELECT name, color FROM user")
]
over and over?my experience is the exact opposite. People who love and advocate the merits of ORM insist that everything be executed through ORM because it introduces too much complexity for them to blend handwritten SQL with the ORM generated queries
There's no (good) ORM that doesn't let you simply put your own query in.
I definitely don't agree with the "all queries must be executed through the ORM", and think that dogmatic stance has done a lot of damage to the ORM brand. :-/
The issue is, your lowest value queries are always this type, then you get the 10-20 in any code base that are 100x more complex, and they are the ones your end users care about the most.
You end up with a 80/20 principal in the wrong way, it's great at producing queries that represent 20% of the value of your app, and awful for the 80% that define the core value of it.
I've always heard a major selling point of ORMs is "You don't have to write the actual SQL anymore"
Because of that, I tend to not trust people who use ORMs to even know how to write queries by hand in the first place
My nuanced articulation is "you don't have to write the _boilerplate_ SQL for the 90% of just-do-some-CRUD endpoints in your enterprise SaaS application, but you 100% need to 'know SQL' for the last 5-10% of ~reporting/analytics queries that the ORM is going to mess up".
From my experience, you are mistaken on that. Those queries mostly come with some joins, either necessary or not to represent the object, and that often could be avoided if the data wasn't mapped into some standard object.
By your definition PDO would qualify https://www.php.net/manual/en/class.pdorow.php
Here's a full report for you https://gist.github.com/hparadiz/a1fe30e88dbbe070878a7ea4f72...
Years ago I was working on a project that used knex, then I serendipitously discovered slonik through this blog post, https://gajus.medium.com/stop-using-knex-js-and-earn-30-bf41... (slonik has subsequently had lots of development since then). I decided to rewrite the entire persistence layer from knex to slonik over a long weekend and I'm so happy I did. I liked slonik so much that it was the only time I personally contributed to a programmer through GitHub Sponsors.
But this gets to the heart of what I was saying. I'll grant you that ORMs save a little bit of boiler plate up front (but not much - ORMs have plenty of their own boiler plate, just instead of a universally understood language like SQL they have it in their own custom config JSON/yaml/XML), but that is where I spend a teeny fraction of my time coding. Writing "boilerplate" SQL for a decently large project (say 50-100 object types) takes me maybe an extra day in coding time. I have wasted multiples of that time trying to track down a single weird ORM bug, or poorly performing query. Plus, spending that time up front to write my queries is always the least stressful time of the project. What is most stressful is when my site is finally getting a big traffic push, but then something causes the DB to crater and the leaky abstraction of the ORM makes it ten times harder to debug.
Are you dumb or are you just pretending? I’m going to guess the former!
But that's just me
One of the sticking points I've found in the past is if I create a new table outside of the ORM, it doesn't know how to use it. Then if I try to add it to the ORM's model it doesn't use the existing table, it creates a conflict. Annoying stuff like that
Confused at what you’re evening trying to say here. Are you suggesting that 100 lines of application layer code is easier to understand than 15 lines of SQL?
2. No, my point was that talking about code clarity was a distraction because to talk about lines of code as a determinant of performance is clearly wrong.
3. Tangentially, yes, if some behavior takes 100 lines of general purpose code to express, I would rather read it in the general purpose language than in SQL even if the SQL was fewer lines. It's hard to imagine why this would ever be the case though.
ORM is ultimately SQL
The overwhelming majority of OLTP queries I see running on massive prod systems execute in < 1 msec. More time is spent in network RTT than execution, let alone the ORM parsing the result.
2. Query performance is dependent on the query and table size. They won't all be < 1msec. Not everything can be an indexed O(1) lookup
3. Generally speaking, network RTT and query performance is going to dwarf time for ORM to parse the result
4. A raw SQL driver ALSO needs to parse the result if you want to do anything with the data in the general purpose language
You wrote the exact opposite of my opinion here which is why I replied to your specifically:
> People who love and advocate the merits of ORM insist that everything be executed through ORM because it introduces too much complexity for them to blend handwritten SQL with the ORM generated queries
I believe strongly that good ORMs expose the ability to put your own queries in. But I can't possibly boil down all the reasons for this in one HN comment.
An ORM is not a query writer. It's a way to map SQL primitives to run time primitives in a static deterministic way backed by a suite of unit tests.
If you have a special query you wanna run that has 10 joins, 2 sub queries, and a derived view that's totally fine. No one says you can't. However remember that statistically 99.9% of all queries are not that.
https://the-php-bench.technex.us/runs/1
But the speed is irrelevant as long as it's good enough. Notice Laravel's Eloquent at the bottom of the list yet thousands of projects are being built with it regularly.
The tldr is if you're ever concatenating strings in order to build a query you're just doing what the entire job of orm is but rolling your own and chances are you'll end up with a bunch of bugs in how you handle well.... Everything.
I get the first part, but not the second.
Preferring to use SQL rather than an ORM + SQL is all about understanding the subject matter, which is the data as it exists in the database.
> The tldr is if you're ever concatenating strings in order to build a query you're just doing what the entire job of orm is but rolling your own and chances are you'll end up with a bunch of bugs in how you handle well.... Everything.
Yeah, so basically don't do this, except when you have to, like concatenating placeholders for a variable size IN query.
There's some classes of applications where it's hard to write all the queries because there's all sorts of mix and match stuff happening. Those are pretty much doomed to poor performance if the tables are large, so I would rather not play on those teams. On the bright side, the limit of a small table gets bigger every ram generation, and table scans on nvme aren't so painful either.
That's not been my experience. But admittedly, I've usually been brought in when the slow query is killing the database. Then I look at the query that nobody with any subject matter knowledge would have written, come up with an alternate query that will give either the same result or something close enough. Sometimes I have to then dig in and figure out how to make that happen, because the ORM user doesn't always know how to make direct queries.
But it sure did make the easy things easier, as the other poster said.
Ok then!
From experience, I don't. ORMs are usually sold as 'learn this instead of learning SQL'. For many, the ORM creates the tables, alters the tables, and queries the tables; they don't see SQL and they don't know SQL. When that works, it works, but when it falls apart, they have to debug the SQL and the abstraction layer. I'd rather have fewer unnecessary abstraction layers.
> If I pull a datetime from SQL there's a lot of value in having a single piece of code handle that datetime the same way across the entire stack.
There's value there, datetimes are very complex, but the rest of the stuff it comes with obscures the value IMHO.
> Obviously you are encountering code made by people who don't understand this but the problem isn't the ORM. They would have made that mistake with or without an ORM.
It's hard to write the kind of complex queries I've seen by hand, and I like to imagine if you out how to do that, you'll also know why it's slow and not need my help... But the ORM is part of the problem, because when you've written bad queries by hand, and I give you a better query (or sequence of queries), it's easy to apply. When you've done it with an ORM, you may not even know where the query is made.
Almost all ORMs boil down their queries down to a single query handler so it's actually super easy to find the query.
My ORM for example:
*Read paths*
- Models/Factory/Getters/GetAllRecords.php:28 - table(...) when indexField is set.
- Models/Factory/Getters/GetAllRecords.php:31 - allRecords(...).
- Models/Factory/Getters/GetAllRecordsByWhere.php:95 - table(...) when indexField is set.
- Models/Factory/Getters/GetAllRecordsByWhere.php:98 - allRecords(...).
- Models/Factory/Getters/GetRecordByWhere.php:20 - oneRecord(...).
- Models/Factory/Getters/GetByQuery.php:9 - oneRecord(...).
- Models/Factory/Getters/GetAllByQuery.php:9 - allRecords(...).
- Models/Factory/Getters/GetTableByQuery.php:9 - table(...).
- Models/Versioning.php:122 - revision table(...).
- Models/Versioning.php:124 - revision allRecords(...).
*Write paths*
- Models/Events/Save.php:41 - insert on save() for phantom records.
- Models/Events/Save.php:53 - update on save() for existing dirty records.
- Models/Events/Delete.php:18 - delete by primary key.
- Models/Events/Destroy.php:24 - insert history row before destroy for versioned models.
- Models/Versioning.php:180 - insert history row after versioned save.
Error/retry path
- Models/Events/HandleException.php:35 - direct $connection->exec(...) for auto-creating missing tables.
- Models/Events/HandleException.php:43 - direct $connection->query(...) to rerun the failed query after table creation.
All of those eventually bottom out in IO/Database/StorageType.php:119 for non-result queries via PDO exec, or IO/Database/StorageType.php:149 for result queries via PDO query.
I used to profile all my queries in those two methods but with tools like NewRelic there's no need to slow the code down with profiling cruft.That being said, if orms didn't force you to explicitly define your domain models about 60% of developers would simply never do it. And you would see differently structured, ad-hoc interfaces defined all over the code base completely entangled with whatever action they are trying to perform.
ORMs being a forcing function for domain modeling is enough benefit for me that it outweighs all of their obvious limitations.
That was a surprising take!
I know only a few ORM's but it seems they end up just adding another layer of DTO objects that are entirely separate from the domain classes anyway. So best case the ORM is just a detour for a good domain model. Worst case it creates a weird database-contaminated domain model that's hellish to maintain.
So I would't say ORMs force domain modeling, or even help. Are you perhaps thinking of a particular stack where the ORM is just one part of it?
Entity Framework in particular has come a long way in this regard. Particularly owned & complex entities, value converters, etc.
https://learn.microsoft.com/en-us/ef/core/modeling/
> Worst case it creates a weird database-contaminated domain model that's hellish to maintain.
CQRS is good for this because it forces you into using a different write and read model. My write models are domain objects and my read models are DTOs that feed the UI and via projection I can shape them without issue.
I personally think that ORMs are good for management and simple CRUD cases, QueryBuilders are good for managing more complex queries while still being secure / type-safe and for everything else a thin database abstraction layer for native SQL queries with parameters / prepared statements is still required especially for performance use cases.
I for one think that "simple CRUD cases" is bullshit, those applications don't exist. In practice, System-of-Records systems are rare. (and should be, their value are inversely proportional of how many of those you have in your overall system).
Because if it was "just simple CRUD", one would use the database directly? Databases are already capable of handling CRUD and much more with way less implementation bugs.
Even assuming your application "is a system-of-record", how is it giving any more value that directly using a ready-made solution like Oracle REST Data Services, or PostgREST?
Ideally models are generated from SQL schemas, which you map to domain models.
I’m thinking about what Rails would look like without activemodel and activerecord. Or even just without activerecord, where we had to write the same sql every time we wrote a model but introduce the opportunity for a dev to screw it up. Imagine starting on a legacy code base and all the models had subtle differences in how they query the db. They don’t have the established conventions around _id fields, polymorphism, the nice bits around joins, and instead you have to discover bugs where you did a join but the two models each have a field called “description”…
I think ORMs do too much. I want to control the querying, or, more precisely, I want to control the SQL that goes to the planner. The good ones largely do allow for this, but I can't think of one that has innate support for vendor-specific features.
What I do appreciate is that they handle the boilerplate like managing connections, preparing statements, setting parameter values, and mapping database types back to client types.
No, because if the schema is the only reference for data models, developers on any sufficiently large team will come up with extremely widely varied queries to access equivalent information. Those are more likely to be incorrect (someone with domain expertise on one set of tables might miss that authoritative data needs to be joined/queried from elsewhere), harder to update when schemas change (more client code changes to alter and test), and more likely to miss performant techniques to query data.
Those can all be addressed with disciplined use of views or common utility SQL snippets or functions, but ORMs also get you to that point without requiring as much ongoing discipline, care, and feeding.
To an extent, yes.
But to the extent that a so-called impedance mismatch exists, this is going to put your domain model on the faraway/difficult side of that impedance mismatch.
And will result in your domain model existing in an (on average) less expressive language which is more difficult to test.
This was never the experience I had. If anything, people tend to plan too much.
One example is starting with NOSQL and proceeding to learn how to make it into a relational database.
That ORM's absolve you from having to learn SQL.
Once you understand that was never actually true to begin with you can treat the ORM as a tool that simply helps you generate repetitive boilerplate queries and hydrates result rows back into objects for you.
Furthermore, if your objects are long lived (e.g. client-side apps) then ORMs offer you helpful features like identity mapping, unit of work, and change tracking/events.
I'm also convinced most of the people poo-pooing on ORMs just haven't worked on problems where these kinds of features are useful. I mean, if you're writing a reporting tool that just queries the database and dumps the result to a table then yeah you might not need an ORM for that. It doesn't mean that ORMs don't solve useful problems for other use cases though.
The author basically says this in the first paragraph, but the title (and some of the language the author uses) implies that people should just use SQL.
It's a reasonable article pointing out some of the annoyances and problems of ORMs (especially in the Java world, where they tend to be overengineered) but there are still a lot of advantages to them if you are in an OO language and they used in a reasonable way.
You can optimise your schema for the convenience of your application code, or you can optimise it for the truth of your domain model. The former makes glue code easier. The latter gives you stronger constraints, better performance, richer queries, and a database that can answer questions the application code never anticipated.
ORMs are bad - I’ll just use SQL.
Hmm - I need to map these results onto objects I can use.
Hmm - wouldn’t it be great if the object tracked changes and could save itself.
I need related/child objects - wouldn’t it be great if I could auto fetch them. …
I've written complicated stuff where an ORM isn't appropriate, but if I'm honest, a large fraction of what I've done in my career is just making boring software to automate menial clerical work, and ORMs are good enough for those kinds of projects.
You've got that backwards. If a tool obscures complexity such that a developer using it could be tricked into thinking their efficient-appearing code is actually inefficient, the problem is the tool. A well-designed tool makes inefficiencies explicit. "You're holding it wrong" is not engineering advice.
> ORMs are good enough for those kinds of projects.
It's all good as long as you have properly abstracted it away from your core application. The trouble with some ORM toolkits is that they encourage you to move database logic into the rest of the application and that's when the messes begin. The old school PHP programmers will know well that SQL in raw doesn't automatically mean proper separation of concerns either, but it is more likely to push you in that direction.
And then there’s the “now you have two problems” dynamic. You not only have to write high-performing queries, but you have to get the ORM to generate that query for you. And sometimes you don’t want objects. And the schema mapping has to track schema changes.
Just write the damned SQL, it’s not that difficult.
I remember those times! Had to write the LINQ, see what it compiled to, redo, until the query was efficient. Abuse LINQ subtleties in how it generated JOIN predicates since it only supported equality. Something about finding an equivalent way of expressing a query with sub-selects that is also computationally equivalent. All so I can get my efficient SQL without writing SQL. So silly.
What ORMs have taught me: just learn SQL - https://news.ycombinator.com/item?id=28812506 - Oct 2021 (24 comments)
What ORMs Have Taught Me: Just Learn SQL (2014) - https://news.ycombinator.com/item?id=24845300 - Oct 2020 (291 comments)
What ORMs have taught me: just learn SQL (2014) - https://news.ycombinator.com/item?id=21031187 - Sept 2019 (634 comments)
What ORMs have taught me: just learn SQL (2014) - https://news.ycombinator.com/item?id=15949144 - Dec 2017 (348 comments)
What ORMs have taught me: just learn SQL (2014) - https://news.ycombinator.com/item?id=11981045 - June 2016 (295 comments)
What ORMs have taught me: just learn SQL - https://news.ycombinator.com/item?id=8133835 - Aug 2014 (234 comments)
Overall, seems like it got more nuanced over time - even though it's still broadly in favor of SQL. Favor for ORMs (flagged also as a term that can mean many things to different people) is more in terms of type safety, mapping, migrations, etc. so more a library/utility rather than a framework that fully abstracts away the database.
That being said, what's the closest alternative that satisfies this - "mapping rows to a code object" - that doesn't suffer the same problems as an ORM? A middle ground between an ORM (like SQLAlchemy, for example) and "your rows are returned as a key/value dictionary where the column names are keys" type approach like Python's DB-API's DictCursor or PHP's mysqli_fetch_assoc. Is there a middle ground here?
ORMs build queries for you, but a query builder does not need to be an ORM.
Sometimes ORMs and query builders are combined into a higher order system, such as what is described by the active record pattern. This might be what you are actually thinking of instead?
ORMs are for storing objects.
SQL is for correctly modelled data.
1. the functional/immutable nature of Elixir makes read and writes much more explicit and there is no need to magically track deep mutations of nested objects to translate them back into UPDATE/INSERT queries
2. Elixirs support for lisp-like macros allows for an ergonomic embedded query languages that is syntax and schema checked, mirrors raw SQL really well and, frees you from string-oriented query building
3. the query builder DSL addresses one of the main weaknesses of SQL query statements not being composable
4. The automatic conversion between JOINed tables (on the DB side) and nested structs (on the Elixir side) is done on the right abstraction level to work reliable and and being explicit enough to generate predictable queries.
As a .NET developer I think EF Core has made the right call here, by allowing you to write SQL where it's needed and still use its infrastructure for all the tedious work of materializing your results.
Admittedly in 2014, the time the article was written at, I've also felt using OR-Mapper is a dead-end. But in 2026 the world isn't black and white.
I always inevitably want to model something in the domain in a way that is not be supported by EF. So I have to maintain EF DTOs and basically give up on the change tracker.
If you don't use an ORM, you'll end up with more boilerplate from mapping code with DTOs. The reason to use an ORM is dirty checking. It's hard to impose this kind of "state" with a relational database. But fundamentally, relational data doesn't fit well with OOP. In the end, you inevitably have to create a layer that absorbs this mismatch. Both approaches have their pros and cons anyway.
Isn't it just a matter of using it where it fits and not using it where it doesn't? I wonder if we really have to frame it as "never use this" or "always use that."
Actually, on second thought, I take it back. "Right tool for the right place" is harder. If you're on a team, it's probably better to just pick one: either don't use it at all, or use it everywhere. Because either way, friction is going to happen. My earlier thinking was too shallow.
I’m surprised more languages don’t copy this because it’s exactly what I want rather than loads of complexity that eventually always breaks down.
Honest question -- what's the difference?
Usually the problems with ORMs stem from the fact that they are exactly clever functions that write SQL. The cleverness abstracts features of SQL that are important for performance and also makes it easy to do things that are bad for performance.
I'm not saying that the ecosystems you mentioned aren't doing something different, I just don't know what it is from how you've described their DB layers.
query = from u in User, where: u.age > 18
Repo.all(query)
And there is no magic (At least very little). For example, if you wanna access something that is in another table, for example, you're on a user and you wanna access their posts in many frameworks, if you try to read their posts, they would be automatically loaded from the database but in Ecto, you need to explicitly preload them. That avoids accidental and n+1 problems because you can plan your queries more. You're not gonna trigger a lot of queries without realizing it.
Elixir
from u in User, where: u.age >= 18, select: u
C# var adults = from u in users where u.Age >= 18 select u;
I don't use .NET anymore but lately I've been happy with Drizzle for TS. It's very performant and expressive. After years it seems that they're finally going to release v1.0 soon.
Personally I would never go back to writing all my queries with SQL, manually mapping the results, etc.
Sooner or later you are going to hit enter, wait a few seconds and say "oops!"
There's immense value in everything being typed from the API down to the DB queries.
// EF-inspired type-safe API in TypeScript
const query = (q) =>
q
.from("users")
.where((u) => u.age >= 18 && u.email.includes("@company.com"))
.orderBy((u) => u.name)
.select((u) => ({ id: u.id, name: u.name, email: u.email }));
Of course, ORMs are not for all queries in your project, and may not be a good fit for some projects. That goes without saying. The problem with the article is that it's dismissing ORMs by looking at specific implementations.2026: people respond with indignance that they should have to learn anything now that there's a shortcut
But the current shortcut du jour is pretty damn good at writing SQL.
Once you hit a certain level of complexity in your queries, you're better of with SQL. It's not that you can't do the query in the ORMs, but you're then looking at learning their special query language and those are never better nor easier to understand than just SQL. Those ORM query languages certainly aren't transferable across ORMs, but SQL frequently is. If you can query MariaDB with SQL, you can query SQLServer and PostgreSQL. The same can't be said for e.g. Django vs. Hibernate.
For the "give me all the entries, with this one property" ORMs a much quicker and easier to work with. Once you start needing to use subselect, multiple joins, weird ranges or constructing object with data from across tables, I'd rather just write the SQL myself.
I enjoy this article[0] about some of the persistent warts which will seemingly never change.
It's not a matter of "fractional speed difference" unless your database has very few entries. OR mismatch problems often like to appear shortly after your database starts to see any real use.
The only performant way to use an ORM is to use escape hatches everywhere. Alternatively, you can use an "ORM", something which calls itself an ORM while only doing superficial data mapping into dynamic or generated native (to your language) data structures. There are a _lot_ of these, most normal people call them query generators.
There are rather concrete problems that strictly prevent it from being possible to efficiently map graph (object) database access patterns to a relational database.
Do you mind going more into that? Naively, it seems like prolog/datalog describe graphs pretty well and they're inherently relational. Relational databases have typically just optimized for row-oriented OLTP uses instead of columnar OLAP, but there's nothing inherent preventing one or the other. They're duals of each other.1. They pretend SQL is standardized, and support a heavily reduced featureset for any given database as a result
2. They leave awkward holes in their abstraction, leading to psychotic behaviors like N+1 and implicit type coercions to helpfully break your indexes silently
3. They make simple queries simple, and hard queries absolutely revolting
4. You end up not wanting to use the objects directly anyways, so you end up with object-object-relation, needing a mapping layer from your database-object to your business-objects, which also defeats most of the benefits from change-tracking
5. The generated SQL is periodically utterly nuts, so you have to review every generated query anyways
6. You probably dont want to actually use any of the OOP mapping features like inheritance in your DB
The correct answer is to use a query builder + database model, enabling most queries to be written with some degree of type-safety, and minimizing the abstraction from SQL itself, and toss out the rest of the featureset
(1) and (3) are not really problems with an ORM that gets out of your way and lets you drop down to raw SQL when necessary, but still helps you hydrate result rows back to objects (and still provides the associated features I mentioned previously).
(2) and (5) can be interpreted as "your ORM does not absolve you from knowing SQL".
I've never personally run into a situation where doing (4) or (6) were desirable.
> The correct answer is to use a query builder + database model, enabling most queries to be written with some degree of type-safety, and minimizing the abstraction from SQL itself, and toss out the rest of the featureset
If you work on projects where a full featured ORM can be replaced by a simple query builder then cool, but the rest of the feature set is really useful for the projects I work on so why would I toss them out?
If it was just a query builder we could have a conversation about the benefits of that vs sql and when one beats another. But it is all kinds of other features that are implicitly activated and then conspire to ruin your day when you were trying to solve some other problem. ORMs bring too much baggage by default. So now you have to talk about its relative merits compared to just writing SQL and the merits of always having these other features activated. Which other features? You need to read your full ORM manual because they really vary from one to another.
And frankly this list hasn't changed in 30 or maybe 40 years now.
And DBA's were so notoriously egregious that Martin Fowler made his "NoDBA" blog post over a decade ago now. And the movement to NoSQL definitely made things worse.
I wish the SQL community would stop treating ORM's like the vietnam paper did 20 years ago, and embrace them for what they are, as a stepping stone, and maybe as a useful tool to help people understand SQL itself.
4 is in the "like so what" category.
5 - it optimizes alright for average case. You have to optimize in edge cases, but then again, you have to optimize edge cases with pure sql too.
6 - no I dont want much inheritance in db whether i am using pure sql or orm.
EF Core is provider-specific and also exposes provider-specific functionality.
> 4. You end up not wanting to use the objects directly anyways, so you end up with object-object-relation, needing a mapping layer from your database-object to your business-objects, which also defeats most of the benefits from change-tracking
This just isn't true for EF Core. https://learn.microsoft.com/en-us/ef/core/performance/effici...
> 5. The generated SQL is periodically utterly nuts, so you have to review every generated query anyways
Not universally true either. You only have to review complex queries. If you're making claims about a specific ORM it would be good to mention it as it's not universal.
> 6. You probably dont want to actually use any of the OOP mapping features like inheritance in your DB
Then don't? Since when is inheritance required for ORM-usage?
I have found a lot of the anti-ORM critiques come from either using a crappy ORM or having not used a good one in the last 5 years.
Hmm – I should model the data according to the domain, not according to the shape my application objects happen to want.
Hmm – maybe “related objects” are not things to auto-fetch, but relationships the database engine is already built to handle.
Hmm – now that my schema matches my domain, complex problems can be solved with a few lines of SQL, saving me hundreds of lines of application code.
Hmm – in fact, now I realise that many important operations can be performed without round-tripping the data through application code at all, saving me thousands of lines of application code.
Similarly, designing your schema to match the domain does not necessarily grant you the productivity boons of an ORM.
Having (ab)used Postgres with and without ORM, I've never had a situation where the latter imposed any kind of design decisions on the schema. They're orthogonal concerns. Itself, the choice of using an ORM tends to be motivated by experience with certain requirements in the business logic. I love SQL, but when having to deal with API resources and their various representations, marshaling, validation, options, etc, it's difficult -- and to say the least, impractical -- to stay principled to the "no-ORM" and "raw-SQL" mottos.
Mapping database rows to domain objects really isn't that painful and you only do it once. So not a big deal. LLMs actually make this a non-issue now.
I actually realised I like the separation of domain objects and the data layer. It just makes things easier to think about for me. And it means my data layer is completely abstracted from the domain. Makes it easier to implement different storage/caching strategies.
And I also realised, if your hot path is needing to get related/child objects then you should probably just write an optimised query as a prepared statement or a stored procedure. It's rare that you actually have that many different ways you want to access the data.
They are really useful for speed of development though if something is completely greenfield and you don't know the full picture of how data is going to be accessed.
What sql client is going to hand you raw text?
> Hmm - wouldn’t it be great if the object tracked changes and could save itself.
Lost me there.
Most of the time you’ll be able to simply use the ORM, but every so often you’ll inevitably come up against a situation where a custom query gets the job done better, and you’ll still get the benefits of deserialising to objects that the ORM offers.
To have all this ease of use you give up so much in performance.
Most apps and companies never get to the point where performance matters that’s why we have ORMs.
Not really. ORMs (memory) and databases (disk) are distant by multiple orders of magnitude performance wise. Skipping the ORM to shave off some cycles is akin to haggling over a few pennies on your thousand dollars bill.
It's more of a Micro ORM, -but- has a Linq DSL, as well as DSLs for lots of DB bits. CTEs, Window functions, Bulk copy, 'treat this in memory collection as an input rowset', certain DB Specific bits... and if you need some special sauce to deal with brownfield jank [0] it's very easy to wire-up custom SQL bits into your queries via attributes if needed.
If you use method syntax rather than linq query syntax, you will have minimal surprises with the SQL generated. Typically if it does generate something I didn't expect, I dig in and what it did was indeed both correct and better than what I was trying to do anyway.
[0] - Fun nasty case I ran into on a brownfield project; 'If this number has a decimal point, it is a direct percentage rate. If the number does NOT have a decimal point, it is the FK to a lookup table that has the percentage rate'
Database rows map to structs. But it doesn't try to figure out how to mutate the data for you to keep the struct in sync with the database. All mutations are explicit using changesets (which can also be used for other non-database purposes, like validating user input for an API.)
There is no implicit preloading of data. You have to explicitly preload.
Data is never fetched implicitly. You have to call Repo.all or Repo.one or something.
It has a query DSL that's a thin wrapper over SQL. It's well-designed and I've never had a problem with it.
Ecto is by far the closest thing to a perfect pattern for abstracting over sql that I've ever seen. I WISH other languages would create similar libraries. Its the biggest thing keeping me coming back to elixir for any kind of database project. it just makes sql so ergonomic.
The article seems to be confusing ORM with query builders. Query builders are where you might avoid writing SQL. ORM is a data transformation technique.
Even when you had to do this manually, it was a very minor effort. A one time thing. These days of course any half decent LLM will produce this code without much fanfare. The argument just melts away.
Otherwise, ORMs just layer abstractions on abstractions. You end up with these weird half implied joins resulting in absolutely terrible actual joins happening. Unless you actually understand what you are doing, in which case you could be hammering out those joins manually. And of course the underlying SQL is usually a bit richer than this one size fits all nonsense ORMs do in order to work across sqlite, mysql, postgresql, etc. and pretend that it's all the same.
Another issue with ORMs is the object impedance mismatch where a junior wannabe coder thinks it's all just objects and classes and you end up with these gazillions of completely pointless tables that then necessitate a huge amount of joins. Often the right amount of tables is a lot smaller.
Also, if you aren't querying on it, does it really need its own column? I end up using my databases as document stores quite often. Gets you the best of both worlds. You get to query on nice indexed columns and then you deserialize the big blob of json or whatever into your rich object structure. Simple CRUD for objects shouldn't require a whole lot of engineering. It's only when every little object needs its own little table that shit gets complicated. And another benefit is that this usually results in more stable table structures that don't need a whole lot of database migrations. Getting rid of those removes a lot of needless faff from day to day deployments.
Maybe if you’re fetching data from a single table… once you start joining across multiple tables and need deduplicate your result rows it gets pretty annoying to do it by hand though.
I recently added support for SDK generation in Rust and Go, just do `disc codegen —rust` (double dash, my iPad is autocompleting the wrong dash) and you’re good to go.
[0]: https://disc.sh
But this is caused by another shift (I didn't experience this firsthand so bear with me); early databases often had multiple clients, nowadays it's often a 1:1 relationship with one application owning the DB. Which makes putting in constraints in SQL feel clunky.
The biggest casualty of that is probably stored procedures.
Then I went off and did distributed systems and HPC work for a decade or two, and the closest I got to "databases" was when we had to interact with LDAP. But, eventually our R&D contracts shifted and we were mixing with bioinformatics people. Then, we had a need for structured metadata management, and RDBMS seems like the right tool. So I finally had a reason to teach myself SQL, with a range of OLTP and analytics sorts of workloads on PostgreSQL.
I have found the existing ORMs in our Python landscape to be really alien and off-putting. I much prefer using the lower-level DB connector and doing my own SQL query building. We also do a bunch of generic/polymorphic work, defeating the main theses of ORMs. Mostly, our schemas are not known at development time, rather they change dynamically. There is no sense in mapping schema to classes, since a developer would have no contact with such classes. Instead, our code has to do "metaprogramming" about table definitions, keying, and reference patterns at runtime.
> You can learn something like ~90% of useful SQL in an afternoon.
Oh, HELL NO!It's an ugly little language that one has to come back to and re-learn over and over at different levels of sophistication. Nothing wrong with that, but to suggest it's trivial is a gross mischaracterization.
Totally agree. Views as a data API is the best way to take advantage of the facilities that the database itself offers and guarantees enforces consistency across disparate clients.
Ah yes, the famous database integration anti-pattern.
> but ORMs also get you to that point without requiring as much ongoing discipline, care, and feeding.
[citation needed]
The fact that you have being practising "database integration" won't suddenly disappear just because you used a ORM. In fact I expect even worse database integration from your average ORM user, as people that uses ORM blindly often don't care (to their own detriment) about "silly issues" like data provenance or persistence mechanical sympathy.
At some point I expect the DBAs of such database integration nightmares will have to start handling stuff like column-level security and row-level security to prevent naive users from shooting themselves in the foot.
I am not using ON DELETE CASCADE to be clever - the referenced data is genuinely required.
I think ORMs mostly exist because most programming languages tend to lack an elegant way to write SQL and interact with results. Somewhat ironically, the much-maligned CFML (aka ColdFusion) got this right decades ago. It made SQL string building trivial, and it provided a native data type for tabular query results.
No other language I'm aware of has this, and it's the missing piece in many modern ecosystems. They do not need an ORM. They need better ergonomics for interacting with databases: a clean way to compose queries, execute them, and work with the result as structured relational data rather than shoehorning it into application objects.
What you do need is some kind of boundary mapping layer so that your application isn't tightly coupled to the database. That might be a an RRM instead, but if you are going to all the trouble of adding an RRM, why not an ORM? What's the difference, really?
Relational databases can represent graphs, and graphs naturally have relations, but in your OO language you can make choices about how to traverse an object graph based on external state, and such traversal is incremental and dynamic. Relational databases can have recursive queries, and these can be used to traverse graphs, but the shape of the query has to be known up front. Recursive queries can be dynamic over database state, but not over arbitrary external state. Even assuming some incredibly deeply integrated super-ORM, it's easy to imagine how programs that operate on graphs _and_ can be automatically mapped to an efficient set of relational queries are a limited subset.
This is the fundamental object-relational mismatch. You can use escape hatches, or you can contort your code, but every time you do this, you have to accept that you're no longer "mapping" in the transparent sense that ORMs were supposed to provide.
I think probably the easiest way to get an intuitive sense for the problem is to consider a simple object graph model:
User {
name
friends: List<User>
posts: List<Post>
}
This is a mostly natural way of structuring this data. One natural (albeit contrived) operation might be: user.friends[0].friends[0].posts
If you had a reason to do this operation, most people wouldn't think twice about it. There's overhead from the indirection, but nobody would think of this as an excruciatingly slow operation if working with native objects.Now, how do you create an object that is backed by a relational database while still transparently letting you perform object-graph traversals such as the one above? It's easy to see how `User` would need to be an object with a `name` field. Since the data is recursive, you probably don't want to eagerly load all friends and posts, so you'd have proxy objects that make additional queries when you access them.
It's easy to see how this leads to the classic N+1 style issue. You have your user, you load their friends. Maybe your proxy object is smart enough to only load only their first friend. You end up making a bunch of additional queries after the first one to load the user. Especially when your database is on a disk and large, or accessed over the network, you can see how this quickly gets out of hand.
In the object/graph model, the relationships are _internalised_. They're represented _within_ the object. But in the relational model, relationships are external. To "map" from one to the other efficiently, you can't just represent things as objects with some glue, because you keep running into these "look ahead" issues. When you access user.friends or even user.friends[0], your mapper has no way to know what you're going to ask for next.
Of course, one way to solve this would be with deeper integration or a DSL. Let's say you had a query language which can represent the above query, and then you analyse this query to try to map it efficiently to a relational query. Sounds like we've solved the problem? Well kind of, yes. Except we're no longer mapping the object model to the relational model. A given query leaves you with dead objects, you've just delayed the problem while leaking abstractions. You can add proxies to those but you're now back to square one except you've maybe improved performance a little bit.
If you don't actually need those features then obviously an ORM will offer less value to you. That doesn't mean ORMs aren't useful tools, they just aren't useful for the problems you work on.
I tend to work on projects where those features are useful and if the ORM didn't provide them out of the box then I would need to build them myself. In other words using a query builder alone does not adequately solve the problems I need to solve.
TLDR: Tooling pressure is a design pressure.
Not much can beat stored procs when it is dealing with multi-step heave volume stuff. But I don't miss not having to do hacks for logging and debugging compared to the flexibility offered by non-db side.
For pretty much everything else, the poor ability to log and debug makes them a headache to manage. I
Usually it's due to one of these:
- The domain deals with a lot of things that are not in the database.
- The domain is one of many and deals with just a fraction of what is in the database.
- The domain deals with things stored in several databases.
- The database was designed in the 90s and the domain is new.
- It's not my database so I can't change it.
(Even for greenfield systems I don't think it's generally desirable that the database matches the domain model.)
> The domain deals with a lot of things that are not in the database.
You can have non-serialized properties. You can even can over-ride serialization/de-serialization of individual properties
> The domain is one of many and deals with just a fraction of what is in the database
You can use different ORMs for different parts of your domain, you could even wrap multiple ORMs in a wrapper repo pattern if you want
> The domain deals with things stored in several databases
As above.
> The database was designed in the 90s and the domain is new
Tons of solutions for this, one easy one is using SQL Views, just ask Claude. The weird thing here is that I've now dealt with this IRL like 5 times and came to the opposite conclusion of you. I found wrapping a bad DB design with an ORM a great first step in fixing it, as the ORM effectively acts as an easy strangler pattern.
> It's not my database so I can't change it
You can still use ORMs, ORMs don't have to manage migrations. Though I feel sorry for you working somewhere you still have a DB guy gatekeeping the database design in 2026.
The point is, every one of your objections are pretty trivially solvable with many mature ORMs, because everyone else had the same problems two decades ago and instead of throwing up their hands and hand-rolling their SQL, the ORM tooling was improved.
You have mixed the posts you are replying to - the domain being different from the database is stipulated here.
I was giving examples of how this typically happens, and the reasons are entirely independent of whether or not an ORM is being used.
I am fully aware that you can handle any mess using an ORM as well, which is why I was surprised at the original claim that ORM's force proper domain models. I haven't observed that so I was genuinely curious.
Separately from that I have to say your suggestions of things to do to force an ORM into the situation are bad ideas. The complexity of custom serialization, various mapping hooks or attributes to bless individual properties will lead to pain and misery down the line.
Just accept the extra layer of DTO's. They're a detour over pure SQL but are at least easy to maintain and hold no surprises. They say there's a special place in hell for people who write SQL triggers and I think people who override ORM serializers are welcome there. ;-)
---
It's not usually a DB guy gatekeeping, it's that multiple apps use the same database so layout changes are costly.
User {
name
friends: List<Friend>
posts: List<Post>
}
Let's say we have a "MappedUser" which is derived from this type by this ORM.I now do:
user = get_mapped_user()
for post in user.friends[0].friends[0].posts {
...
}
Ignoring "get_mapped_user()" how does our user object work?What happens when I access `.friends`?
Does it give me an empty list, because I didn't ask for it?
I am not aware of anything that calls itself an ORM which merely does:
user: User = map_from_relational_to_user(query_user())
Not only is it difficult to conceptualise how this operation would ever meaningfully work for any non-trivial query, it's also difficult to see how it would even work for trivial queries.ORMs, at their core, try to abstract away something like `user.friends[0].friends[0].posts` more or less into some underlying queries against a relational database. The main distinction between them being in the availability and first-class nature of the escape hatches when this operation inevitably becomes slow.
That depends on the rest of your code. If you are using something like the active record or data mapper pattern then it would reach out and fetch more results. If you don't have such mechanics in place then an empty list is possible. We don't have enough information here to say what happens.
> I am not aware of anything that calls itself an ORM which merely does
When your code merely does that, what do you call it?
> ORMs, at their core, try to abstract away something like `user.friends[0].friends[0].posts` more or less into some underlying queries against a relational database.
Active record/data mapper tries to abstract that. ORMs are a necessary piece of active record/data mapper, but one part of a larger system. You also need things like a query builder. ORM alone is not sufficient for these patterns.
> into some underlying queries against a relational database.
Unlikely. SQL is mentioned in the headline for a reason. Nobody uses relational databases in the real world. The only remaining relational database engines that are still maintained really only exist for educational purposes. I understand why you might think a relational database is necessary given that ORM stands for Object Relational Mapping, but as ORM operates on data, not databases, the data can be relational even if the backing database isn't. It simply becomes another mapping step to see them become compatible.
No, I am asking about your hypothetical "bare bones" "ORM" which explicitly _doens't_ have anything beyond "object mapping".
> When your code merely does that, what do you call it?
Certainly not _object_ mapping. It's something between regular "data mapping" and "completely worthless." If the thing you get out of it is not something representing an object from your object model.
> ORM alone is not sufficient for these patterns.
You are talking about a definition of ORM which is at odds with any definition of ORM that I am personally aware of.
Classical ORMs focus almost entirely on providing proxy objects which represent your object model and which back accesses with additional queries.
> Unlikely. SQL is mentioned in the headline for a reason. Nobody uses relational databases in the real world.
SQL is a query language for relational databases. Unless you have another definition for "SQL" or "relational database" which is at odds with common parlance.
> I understand why you might think a relational database is necessary given that ORM stands for Object Relational Mapping, but as ORM operates on data, not databases, the data can be relational even if the backing database isn't. It simply becomes another mapping step to see them become compatible.
While certainly an ORM maps between an object model and a relational model, the fact that this could be done with something other than a relational database seems completely irrelevant to anything in this discussion.
You seem to be taking the term "Object Relational Mapping" splitting it into its constituent parts, looking at the definitions of those terms, and then assuming that the definition for the whole term is just a simple combination of the individual terms.
This is akin to me claiming that OOP doesn't require a programming language or computers, and can merely involve me buying or otherwise procuring a bunch of things (objects) and then setting them up (programming) in the form of a Rube Goldberg machine in order to perform calculations.
My earlier statements regarding the example code existed to point out that the mere act of taking some relational data and somehow converting it to objects in your object model is not "mapping" in any meaningful sense because the resulting objects would be incomplete, and in some cases would not even be able to be constructed from arbitrary relational data.
The mere act of instantiating a partial object graph from relational data is _not_ "ORM", in the same sense that writing and calling functions is not functional programming.
But that is not what ORMs are. They teach bad habits that make SQL harder to understand, not easier, because the power of SQL depends on good data modelling.
Perhaps the worst habit is treating the database as subservient to the application code. This assumption comes naturally to many programmers. In most programming contexts, file formats, wire protocols, and internal representations are defined by the code that consumes them. That's fine in some cases.
But in a data-centric application, the relationship should be reversed. Before writing a single line of application code, you should understand the domain model and design a schema that represents it well. The database is not just a persistence layer for objects. It is the system of record, and its structure should reflect the shape, constraints, and relationships of the real-world data. Everything else should be built to conform to it.
But a close second is that it encourages composition in situations where duplication is the right choice. Having your sql query spread across 7 files makes tracking down bugs and performance issues (and fixing them) incredibly difficult.
Obsessively cramming tabular data into objects is often unnecessary, and it bloats the code downstream of the database query. It then encourages the bad habit of performing data manipulation in code rather than directly in the database.
"Fetch related objects" is a code smell. If any related data was needed, your original query should have already fetched it.
But in data management applications, the job is to derive specific information from stored facts. For that, SQL is not an implementation detail behind objects; it is the main abstraction. The whole point is to ask for the shape of data your application actually needs, not to arbitrarily hydrate objects and reinvent a bespoke querying engine on the client side. I can barely even remember the number of times that I've ripped an ORM out of a system because the code to interact with hydrated objects had devolved into a single-purpose database engine, a sprawling mess of code, seemingly well organised into objects, but ultimately wasteful.
Often, de-duplicating in code is a perfectly fine solution, and significantly more performant than multiple round-trips. A join that repeats parent columns is not a flaw in SQL. It is only a problem if the application insists on rebuilding a nested object graph instead of asking for the shape of data it actually needs.
If the data returned by the query does not match what you are presenting, the answer should not be to fetch a pile of related objects and interrogate them in memory. It is to use more SQL to further digest the data so that the result set more closely matches what you intend to present to the user.
In my experience, these are typically best turned into views (or materialized views), because they represent some fundamental relationship or property within the data that’s useful to be able to quickly reference or query directly against. KPI aggregates, for example.
Without an ORM you have to write a bit more boilerplate code to interact with the database. But by taking advantage of the power of your database engine, you could potentially avoid writing huge amounts of data manipulation logic. In my experience, an ORM is more of a code amplifier than a code simplifier.
DTOs are one of the big code smells of a code base that does little but will be full of boilerplate. As soon as you see an automapper or a folder of DTOs you know you're in for some serious pain.
On the plus side you also know you can reduce the codebase by about 75%.
I actually agree but think serialization overrides are even worse, and the code smell that causes both of them is the ORM. ;-)
Even if you think that maintaining your domain model is easier in SQL (it’s not, for most full-stack engineers), the extra capabilities you get from an ActiveRecord framework such as full-stack admin pages, free migrations, etc. win overall.
I can believe that the gap is closing with the “api for your Postgres” frameworks but really, try reaching your frontend developers sql and see if they have a better time than learning Django/Rails.
One lesson I've carried for years is that most of the time the client needs denormalised views on the data model. That's the boundary; the server has the clean domain model, and the client works with views on that model. Isn't that exactly what an ORM is for?
I built mine in Dart because I want the server and client to share DTOs. Then I built a visualizer for clientside devs to be able to explore entity relationships (DDD style) and generate a JSON contract. The end result is no REST back and forth, no GraphQL complexity, just everyone in the team focusing on what they're good at.
I think the theme that ORMs are easy to start, but you pay for it with the edge cases, so good devs end up back at SQL does not apply when you're thinking about how to build a platform. Everyone has their strengths and weaknesses. Aligning the team on playing to their strengths was my goal when I reached for yet another ORM as the solution.
The naive "here's a row-level view of the database records" that things like ActiveRecord/ActiveAdmin give you by default are entirely inappropriate for any line of business administrative interaction. Line of business admin sites should be workflow based and focused on surfacing specific information needed for processes outside of the admin site itself. Non-developer staff should not be expected to interpret the state of rows and relationships among the tables.
The specific danger of CRUD is that all operations are expressible in it. If your system is CRUD, everything goes. A developer who doesn't understand the system's design might be inclined to assume an application is "just CRUD" and add all sorts of misfeatures to it that violate otherwise constrained states. They will turn the application into CRUD.
All it takes for an application to go from carefully modeled to CRUD is for people to believe it already was just CRUD.
Like, if the simple insert, read, update and delete SQL queries are forbidden then what do you guys do all day?
Are you really doing inserts exclusively based on the data of another table? You never take user input from a website? You never need to just get a list of data according to a query with some filtering?
Honestly I'm not buying it, since the opposite would basically require you to write Hasura style monster queries for pgsql all day.
> Are you really doing inserts exclusively based on the data of another table? You never take user input from a website? You never need to just get a list of data according to a query with some filtering?
None of these go against what GP said in any way.
The only good thing about ORM is the type safety, but I find rust's sqlx or java's jooq to be hitting the sweet spot.
The problem is not that ORMs fail to expose every feature of a particular SQL database. The problem is that they encourage you to model your data in a way that is convenient for the ORM, rather than in a way that is correct for the domain.
Any sufficiently powerful ORM eventually has to provide escape hatches into SQL. At that point, the abstraction has failed: the ORM is no longer helping you understand the database, it is getting out of the way so you can use the database properly.
An ORM is a straitjacket. It pushes you toward sub-optimal structures, and those structures deny you access to the most powerful aspects of SQL: relational modelling, constraints, joins, aggregation, views, transactions, and set-based operations.
That said it’s still my most frequent cause of crashes, however I think mostly it’s just because this is simply a hard problem that SQLite just isn’t cut out for (although it did take Apple until macOS 27 to supply a codable decorator grrr).
Ideally databases could evolve to fit OR mapping more closely, which incidentally is what Arrow and Parquet have done to an extent.
I mean think about it, creating a single row is CRUD, retrieving a row by ID is crud. Retrieving all the rows that belong to a user with pagination is crud, updating a specific row by ID is CRUD, deleting a specific row by ID is CRUD.
You have a settings page? CRUD
User profile? CRUD
Application form with more than 120 input fields, complex tables, split across multiple pages? CRUD
Heck I have a version of that where you get to nest multiple sub application forms into a single application with absurd amounts of nesting and it is still CRUD.
Most cases that aren't CRUD tend to be niche cases.
I mean think about it. An extended search feature that has hundreds of options is still CRUD and tends to work much better with an ORM since the query builder dynamically builds the SQL query for you instead of messing around with a static SQL query with a massive amount of feature flags.
The cases where you don't have CRUD are the rare cases. Things like reporting, batch jobs that process multiple rows at once or reconciliation that tries to find the differences between two databases.
Maybe it's not clear, but the arbitrarily complex application logic obviously is not written in SQL so even if the application is more complex than a straw man CRUD example doesn't mean that the database sees something more complicated than row creation, retrieval, updating and deletion.
...and Django was like this 15 years ago when I first started using it. The core design hasn't changed, it just sounds like most other ORMs don't really know what they're doing.
Django is an opinionated web framework that uses an ORM, not just an ORM.
Django can by all means be a great way to make a web site (I have little experience with it) but if you have a db that is accessed by various systems written in Java, dotnet, erlang or whatever else I suspect the smooth sailing of Django can run into headwinds quickly and the python plumbing you have to deal with then quickly becomes an issue in itself.
But I admit it's just a guess.
Only if those systems are constantly adding/removing tables and columns. And adding isn't a problem, Django just ignores what's not specified in the models.
Django does have default table and column names based on the models that it prefers, but all of it is overridable in officially-supported ways. We're using it with mysql databases originally made for VB6 and C++ with inconsistent naming schemes that aren't even close to Django's defaults, that nowadays are also accessed by perl, php, and python. Most of our python uses are daemons that only use the models and none of the rest of the web framework - the models are defined in a common library they all use.
What does "bare bones ORM" mean? That seems like saying "bare bones sort", but like sort it seems to me like it is either something that happens or something that doesn't happen. You either map objects and relations or you don't. Are you imagining that there is some way to partially map relations and objects but somehow not go all the way? I admittedly cannot picture what that would look like. What would the purpose be?
> SQL is a query language for relational databases.
No. SQL is not for relational databases. This is most obviously observed by the fact that SQL is centred around tables instead of relations. That naming isn't just a marketing gimmick. Tables are technically different from relations. Codd, inventor of the relational model, spent a lot of time writing about why SQL isn't relational if you want a more in-depth technical explanation, but suffice to say that ORMs and SQL are not directly compatible. Although obviously they can work together if you layer in additional functionality. You can make any data shape work with another if you provide some kind of mapping between them.
I am asking _you_ what _you_ are trying to claim here.
If you have a class such as:
@dataclass(frozen=True)
class User
name: str
friends: set[User]
I am trying to figure out how your described model maps it from partial information such as:"user" (user_name) subset:
("Fred")
("Jeff")
("Bob")
"friend" (user_name, friend_name) subset: ("Fred", "Jeff")
("Fred", "Bob")
Because to "map" this to the object model, your relational mapper would presumably need to do this: fred = User("Fred", { User("Jeff", set()), User("Bob", set()) })
But from the above partial information, you don't know if Jeff or Bob have friends.This breaks down further when you add more to the users tuple set, e.g. let's add a required "surname" field.
("Fred", "Robinson")
Now mapping the above would result in: fred = User("Fred", "Robinson", { User("Jeff", ???, set()), User("Bob", ???, set()) })
Unlike with the empty "friends" set case, there's _nothing_ you can put in the names which is correct unless you force those fields to be nullable. This is basically unmappable.I am asking how _your_ idea of an ORM which doesn't handle querying (or if you want to use relational terminology, evaluating relational algebra expressions) works. Presumably you will claim that it will only map data which is mappable, which is wonderfully useless. But then you're just describing the concept of mapping, and not "an ORM" which is a tool which handles this concept for you.
> No. SQL is not for relational databases. This is most obviously observed by the fact that SQL is centred around tables instead of relations.
This is a weird argument. Relational data doesn't centre around relations, it centres around sets of tuples, the relations are an external concept which makes interpreting the dataset useful.
> Codd, inventor of the relational model, spent a lot of time writing about why SQL isn't relational if you want a more in-depth technical explanation
E. F. Codd complained that SQL databases aren't a faithful representation of the relational model, and that's accurate. His complaints were with the following (cited verbatim):
"
* Flaw No. 1: it permits duplicate rows in relations;
* Flaw No. 2: it supports an inadequately defined kind of nesting of a query within a query;
* Flaw No. 3: it does not adequately support three-valued logic, let alone four.
"
Regardless, their use of "tables" has nothing to do with whether they're relational or not. Codd's complaints are to do with the fact SQL databases use bags instead of sets, that SQL doesn't perfectly represent certain relational semantics because the language was rushed and half-assed, and that they handle MAYBE (NULL) half-assedly and lack support for "inapplicable" values.
The thing to note here is that these flaws, if fixed, would have no impact on the OR impedance mismatch, or the ORM problem.
> but suffice to say that ORMs and SQL are not directly compatible.
You are making an appeal to definition here, specifically the definition of the words "Object", "Relational", and "Mapper". "ORM" is itself a marketing term which was coined at some point in the 90s. This was to describe an approach people were taking to trying to map objects in languages such as C++ to _tables_ in "relational databases" of the time.
The relational databases which were being mapped had tables because that's what the papers of the time[^1] talk about.
The earliest paper I can find that talks about "mapping" describes it in terms of query generation and proxy objects[^2]. Although it does describe a "Light Object Mapping" approach which distinctly doesn't model relationships or use query generation, and uses "basic objects" (which do not actually represent an object model, and are instead just data transfer objects (DTOs)). But what "Light Object Mapping" means here is specifically: "just write your own SQL and map it to DTOs by ahnd" rather than describing any automated approach for the problem, which is precisely how it's the only option that gets away with not having a query generator.
It's kind of funny seeing how far back the "impedance mismatch is imaginary" mindset reaches, because it's present in this paper too. A paper which then goes on to explain the significant complexity of this problem and brushes over many of the even harder parts.
[^1]: http://infolab.stanford.edu/pub/keller/1993/sigmod-93-persis... [^2]: https://www.freeengineeringbooks.com/Ebooks/objectRelational...
I claim nothing about "bare bones", so, again, you must clarify what you mean by it before I can do anything with it.
> I am trying to figure out how your described model maps it from partial information...
That's up to the implementation to figure out. ORM isn't a specific algorithm. Is that the source of your confusion?
> it centres around sets of tuples
Whereas SQL does not. You can, of course, map SQL structures onto relations, which may be why you see SQL as being relational, but that's true of any database. You can take a document database and map it to sets of tuples too. Calling a document database a relational database because it can be mapped to sets of tuples is a stretch, however. Relational databases are natively relational, not just able to represent relations.
Most of those are not necessary for 90% of use cases
I'm not taking the piss either
All most people really need to know is table CRUD, row CRUD, and a bit about indices.
For anything more advanced you'll need a DBA, but IMO you unless you are scaling like crazy you will not need much more than that for SQL knowledge. It's really, really not that complex for most use cases
> I really do not think it’s a difficult language to learn.
Neither do I, but there's huge distances between "spend-an-afternoon-intro-on-it" and "learn-it-well-enough-for-occasional-work" and "learn-it-enough-to-build-serious-databases".Of course, everyone in HN is "advanced" so what do I know!
This is more about infrastructure than SQL though. You don't need to know any fancy SQL to do streaming replication or whatever, for instance.
You're correct that being good at Managing Data is a complex domain with a lot of gnarly bits, but I was talking about Writing SQL being fairly easy
> I claim nothing about "bare bones", so, again, you must clarify what you mean by it before I can do anything with it.
I shouldn't need to spell this out, but I am not insinuating anything negative or positive about your approach by calling the description you gave initially as "bare bones". I am simply using "bare bones" as a shorthand to refer to your definition of ORM.
You are claiming that implementing an ORM doesn't require query building, I am claiming that it does. I am calling your proposed ORM that doesn't require query building "bare bones", just as a shorthand to avoid saying "ORM that doesn't do any query building". I hope this makes things clear for you.
> That's up to the implementation to figure out. ORM isn't a specific algorithm. Is that the source of your confusion?
We are talking about _an_ ORM. As I clearly stated in my original comment, and as is being described in TFA. _An_ ORM is a tool which presents a "relational" database's (e.g. PostgreSQL, SQLite, MariaDB, ...) contents as an object graph. With the _external_ relationships (as in the relational model) modelled as _internal_ relationships (as in object graphs).
I am not talking about abstract "object <-> relational mapping" in a vacuum, I am talking about the specific thing that people mean when in 2026 they say "I am using an ORM".
> Whereas SQL does not.
SQL centres around bags of tuples, so you are indeed right that it's not quite truly relational, as was Codd, as I acknowledged. But that doesn't make any impact on what people mean when they say "ORM" in modern day programming parlance. So please stop appealing to an irrelevant definition.
> Relational databases are natively relational, not just able to represent relations.
What do you think this even means? The fact that SQL has bags of tuples just means that if you want it to follow a relational model, you must merely ensure that you enforce these bags to be sets. At this point the remaining complaints by Codd don't have an impact on the fact that, insofar as you don't hit those specific niche limitations, you are faithfully representing a relational model at least in your data.
Relationships in the relational model are not internal, they are external. This is one of the reasons for the OR mismatch. It's counterintuitive that object graphs represent relations internally, and relational models do so externally, at least when phrased like that, but it's inherently true.
The fact that graphs represent relationships also doesn't make graph databases or object databases relational. I would have assumed this was clear from what I wrote so far, but as I already established, I suspect you're not actually reading half of what I am writing, so it maybe isn't so surprising that you think I am ignorant of these things.
If I only read select paragraphs of what Codd wrote, I might also think that he was ignorant of his own model, but instead I kept reading what he wrote until I was confident in my understanding of it. I suggest you do the same if you wish to have a productive conversation on any topic online.
It is, when the "10%" is the actual hot queries that your system will use the most?
Code right now "is so cheap". You can provide your favourite LLM with your database schema, and some domain comments, and ask it a query to fetch/update data, and it will generate somewhat sane queries for you. You can then inspect those queries yourself, send them to another LLM or human to review and, when they look OK, ship it.
And when it comes time to debug it, you have, you know, an actual query, not some pseudo-query in a custom DSL. No need to implement runtime telemetry just to try to figure out if the ORM actually made the query you thought it was supposed to do.
For my projects I would say that the majority of the value an ORM delivers occurs after the query has returned from the database.
But for some reason everyone focuses on query generation as if it were the only feature of an ORM.
I have a lot of fighting against Spring / Hibernate for this. It doesn't let me do cartesian product because the query builder thinks it needs a cartesian product, I can't select only some of the columns without making a whole new data structure while fighting the ORM that thinks one table = one class, can't query from a joined table.
I don't have any issue with mapping using these query builders like jooq which lets you use generated class from the live db for simple use case and give you other mechanism for querying weird joins or aggregates.
What sort of perks of ORM after the query has returned do you find to be helpful?