Comment by aljgz

4 hours ago

I've used Postgres, Oracle, MsSql Server, and MySql in serious projects, no extensive experience with Sqlite, which I know is an amazing player.

These days, I do myself a favor and always avoid Oracle and MySql/MariaDB.

Postgres is amazing, and the two big things I wished it had:

1. lightweight connection; connection bouncers improve the situation, but you still have an unreasonably high memory footprint per concurrent connection.

2. Synchronously updated materialized views (Sql Server calls them indexed views). These are incredible tools in complex data situations. I saw a project struggle with complex technical implementations that would be elegant, trivial and always correct with indexed views.

Sql Server can be costly, but in many cases the benefits it provides are totally worth the cost.

Choosing the data store carefully prevents lots of future trouble.

SQLite and MSSQL are my two solutions for relational storage problems.

If I am going to use a "free" provider, SQLite is impossible to beat. They cover a majority of use cases today. SQLite starts to fall apart with backup, replication and tooling. If I am on the hook for things like system availability and disaster recovery, I don't have a problem spending money to cover my ass.

If I am going to pay any amount of money at all, I am going all the way. The developer experience around MSSQL is untouchable. SSMS and VS with sql projects runs circles around contemporary entity framework crap. Sprinkle in 3rd party tools from vendors like RedGate and you can replace multi-million dollar consulting packages.

I wouldn't ever advocate for standing up a new Oracle or DB2 machine, but if one was already in place I'd probably die on the hill of not trying to refactor it away. These databases typically come with multi-volume ghost stories attached. Reinventing all those weird effects on a new engine will typically kill the business if there are no other options available.

  • >> The developer experience around MSSQL is untouchable.

    This may be the case for MS-centric, application & human developers, but I'm not convinced moving forward. Microsoft's BI story is pretty thin and out of date. Postgres has some solid columnar support/functions (which probably why Snowflake is writing about it) which means you can potentially use it for both you transactional and analytical workflows. As more development shifts to agentic workflows I'd bet Postgres shines when the overall ecosystem is more important than the human tools that were essential for the past 20 years. I loved Redgate's value-add but I don't think agents care about the UI which was the big win. SQL Server will continue to live in the enterprise andf where MS can sell lucrative support contracts or build for their clients, but I'm not seeing any net-new projects where the builders have any choice to not use SQL Server.

  • >I am going all the way. The developer experience around MSSQL is untouchable. SSMS and VS with sql projects runs circles around contemporary entity framework crap. Sprinkle in 3rd party tools from vendors like RedGate and you can replace multi-million dollar consulting packages.

    Try Postgresql. I was previously SQL Server and the move has been great.

    SSMS doesn't offer much over alternatives, both PGAdmin and others. VS is dying, VSCode is the future.

    Redgate doesn't offer anything that is essential or not available elsewhere for postgresql

    The money you spend on Microsoft licenses could be put towards more ram on the server.

  • Can you expand on what is better with MSSQL?

    • One of the biggest advantages is that a lot of people in the business are already comfortable with the ecosystem. I know that from the perspective of HN that SSMS, pgAdmin, DBeaver, DB Browser for SQLite, et. al. are mostly isomorphic, but from the perspective of everyone else in the business, these are substantially different things to think about.

      Whether the popularity of the MS ecosystem is good or not is a separate problem. If we are solving for "make the business go well and I get paid more", the strategy is usually obvious. We can still advocate for OSS and not-so-many-eggs in the Microsoft basket while we get paid for using these technologies. Again, SQLite is the preferred engine in my tool belt. I don't want to have to manage a hosted sql machine. But, sometimes the problem absolutely insists upon it.

      Also, if you are using C#/.NET, integrating with MSSQL is always a little bit easier than the other providers. SQLite (and some others) have lackluster types for things like time. MSSQL has DateTime2 and DateTimeOffset that map exactly into the CLR types.

> Synchronously updated materialized views...

Oh yes, I'd love them too (if you're referring to, in Oracle slang, "...update on commit") - and it would be cool to have as well the option for a lazy update ("on demand" by taking into consideration only the records that have been changed since the last refresh, to handle multiple updates in a single pass - not sure how Oracle can achieve that technically...). This would be in my opinion a fantastic added functionality compared to basically all other (OLTP?) opensource DBs.

And: I'm really curious about the "OrioleDB" project... ( https://github.com/orioledb/orioledb/releases ) as a few years ago I was struggling a lot with "vacuum" of a kind-of-temporary table that had quite high amounts of continuous random inserts & deletes (problem solved by accumulating more changes in RAM before flushing them to the table therefore increasing amount of rows changed per "page", but I had to sweat a lot to find a good balance...).

Oracle = Pain, Suffering, High Costs, Litigation, and Human Misery. If it wasn't for non-technical middle management that likes the perks of buying high cost software from vendors that throw nice parties they'd be out of business.

  • Oracle makes their money by promising the C Suite "give us money and we'll solve your problems." There aren't actually many companies in a position to credibly make that promise.

    The oracle database is also actually pretty nice, according to the people I've talked to who use it.

    But mostly they play in the 'nobody ever got fired for suggesting' club. These days AWS is the most egregious landlord of that club, but whatever.

> 2. Synchronously updated materialized views (Sql Server calls them indexed views). These are incredible tools in complex data situations. I saw a project struggle with complex technical implementations that would be elegant, trivial and always correct with indexed views.

I believe you can do this with the pg-trickle extension.

https://github.com/trickle-labs/pg-trickle

Postgresql is the better product, but doesn't have the horizontal scaling of MySQL/Maria though, so if you want an easy to setup cluster MySQL for high volume online retail store or similar has a use case still.

  • I think we take for granted how few databases ever outgrow vertical scaling needs.

    Usually there will be one or two tables that grow at a dramatically faster rate than everything else and I have always found that those belong in a separate data store.

> lightweight connection; connection bouncers improve the situation, but you still have an unreasonably high memory footprint per concurrent connection.

Pg connections are definitely heavy, but usually on resources other than memory in my experience. If you configure reasonable dirty reclamation and recycling, the memory numbers are often overstated due to Linux tools’ deceptive fork accounting and shared buffers. Ofc, if you’re averaging lots of heavy queries per connection it’ll be truly heavy, but many times the numbers overstate the impact.

Care to share some examples where SQL Server's indexed views would shine?

In my eyes they're similar to triggers, which incur a high performance overhead in OLTP systems and are shunned by developers. In OLAP systems custom ETL code will likely outperform them.

  • In OLTP, it's very difficult to guarantee correctness with triggers (very easy to have a race condition in concurrent environment). On a flip side, materialized views tend to lock more than you'd expect, especially when aggregates are involved.

    The sweet spot is if you have a read-mostly database and use SNAPSHOT transaction isolation for the readers (which is SQL Server's implementation of MVCC). That way, writers may still block writers, but writers can never block readers, even when indexed views are being maintained.

    Another neat trick is to "abuse" indexed views as multi-table CHECKs. The idea is to make a JOIN that would produce duplicated rows (and fail the indexed view's key) if some multi-table condition is not met.

  • Indexed views are much faster than trying to achieve the same result with triggers. Triggers have serious concurrency limitations, and you do recalculations even when the fields you depend on are not touched.

    Indexed views are not much worse than indexes. Of course, when they refer to other tables there are underlying data lookups, but in our experience when we moved from triggers to indexed views, large scale data ingestion went way faster.

    Where we used it: While revamping a large scale sales program, we stored the warehouse in/out in one table, and several things like current stock were calculated using indexed views.

    Bonus: Using Snapshot concurrency control, you can do many things concurrently, and only when they both updates to a certain product in the same store you'll get the second transaction failing (which could be retried on the backend).

    The fact that they are completely in-sync with your data is amazing.

    • PG has had incremental view maintenance on the horizon for many years. I expect it to remain on the horizon for a long time.

      What you're describing is amazing, and I wish I had it available to us. We've hand rolled far too many triggers to achieve the same thing, with all the expected problems you'd assume. I'm sure it could be abused/misused, but a batteries-included approach like that would be huge.

  • These things exist to eliminate the risk of ever serving stale information from a materialised view. I.e., their benefit is political/reputational as much as they are technical in the sense that they save you effort like remembering to invalidate a MV after an ingest operation.

    Stale MV is a thing you only ever burn your fingers on once. Like how "It's not DNS" is a common meme in networking.

two techniques I use with pg:

1. "materialize" the view as a full table, then index that. Any reasonable pipeline/ETL tool can provide incremental updates between tables. Obviously, anything materialized requires considerations around storage, replication, backup/restore, I/O, etc.

2. use a regular VIEW and index (precisely) the underlying expressions mentioned in the view, i.e. so when the view is used, then the indexes get used.

Both require rewriting SQL, though I've used VIEWs to make the change transparent.

I am currently fighting my way off SQL Server towards PostgreSQL.

Windows Server is a real pain to operate and the SQL Server ecosystem expects you to run a lot of add-ons on the server alongside your database. Those don’t translate to managed database services, so you lose a lot of functionality if you jump to RDS or similar.

The first party tools are also aging poorly. SSIS and SSRS are not fun. SSMS is ok for what it is but can’t compete with the ecosystem around PostgreSQL.

Maybe I’m missing something but I can’t wait to ditch it.

>I do myself a favor and always avoid Oracle and MySql/MariaDB.

So what's wrong with MySQL or MariaDB?

  • And although you didn't ask, I'll list what's wrong with Oracle. It's very simple.

    Oracle treats empty strings as being NULL.

    Anyone who's never used Oracle before in their life is probably wondering if I'm making it up. I'm not. In Oracle, inserting '' in a VARCHAR column is exactly the same as inserting NULL. And if there's a NOT NULL column, you're not allowed to store the empty string in there.

    Which means that in Oracle, you do not have any way of distinguishing "I don't know the person's middle name" vs. "I know what the person's middle name is: he/she doesn't have one".

    There are apparently historical reasons for this, but I don't care. The empty string is NOT the same as NULL, and any software that treats them as the same IS BUGGY!

    Sorry. Had to get that off my chest. I know I'm answering a question you didn't ask, but that has been bothering me for nearly 25 years (I first learned about this misfeature of Oracle's in 2002 or 2003), and I just had to vent to somebody who would understand.

    • I'll list what's wrong with Oracle

      Very interesting (and hopefully cathartic). I never got past "it involves doing business with Oracle".

  • 1. No transactional DDL

    2. No MERGE statement

    3. No partial indices

    4. Many ways to lock out instant add table, meaning you can’t add a column without a full table write, which can lock the table for minutes at a time in even moderately sized tables.

    5. Dealing with legacy mysql databases often means dealing with utf8mb3, which used to be the default utf8 data type despite not storing all utf8

    6. Dealing with all but the most recent mysql databases means dealing with non strict mode which means your NOT NULL column won’t require a value.

    • If you are talking about SQL Server, the MERGE statement is basically a bug minefield, I wouldn't use it unless I wanted to deadlock myself.

  • Don't know of anything wrong with MariaDB, but there used to be plenty wrong with MySQL. To give the most egregious example (THANKFULLY fixed in MariaDB, but was present in MySQL for the longest time), inserting the value 128 into a TINYINT column (signed 8-bit int) would clamp the value rather than returning an error. Which might be what you want... except if that was a primary key column. Marvel at the following, which used to be how MySQL behaved:

    Note: the below taken nearly verbatim from https://sql-info.de/mysql/referential-integrity.html#3_5

      CREATE DATABASE foo;
      USE foo;
      CREATE TABLE one ( id TINYINT NOT NULL PRIMARY KEY ) TYPE=InnoDB ;
      CREATE TABLE two (
        id TINYINT NOT NULL PRIMARY KEY,
        INDEX (id),
        CONSTRAINT id_fkey FOREIGN KEY (id) REFERENCES one(id)
      ) TYPE=InnoDB ;
    

    Now that we've created both tables, let's insert a record into table one:

      INSERT INTO one VALUES (127);
    

    And now let's insert a record with a different primary key into table two:

      INSERT INTO two VALUES (128);
    

    MariaDB will give you an error at this point (ERROR 1264 (22003): Out of range value for column 'id' at row 1), but MySQL (at least back when I tried this about ten years ago, which was the last time I was forced to work with MySQL — and I am so glad I never have to go back!) would return no error message and just say "Query OK, 1 row affected (0.009 sec)".

    Now let's select the value we inserted into table "two":

      SELECT * FROM two;
    

    And what do we see? The value 127, even though we inserted 128. Which has created a foreign-key relationship to table "one" that we never intended to put in there.

    There are other reasons why MySQL was inadequate, but I no longer remember them. Probably MariaDB has fixed them by now. But I no longer have to use MySQL/MariaDB for anything, and I never want to go back. I have a VERY strong averse reaction, caused by past pain, when I think of using MariaDB. (I actually spun up a virtual machine to test what I wrote here, because there's no way I was going to install MariaDB on my primary work machine).

  • Just a set of things too minor to move off of it but annoying enough to not want to start with it.

    My list:

    No `explain (analyze,buffers)`. Instant DDL has some warts (e.g. fk, metadata locks). Query planning bugs (actually... query planning in general is disappointing). Exiting the repl doesn't stop queries. Implicit type casting. Replication lag from large DDL (e.g. creating an index). Lack of two phase DDL (creating constraints NOT VALID and then VALIDATE later). Lack of extensions (e.g. pg_vector). No safe access to inspect buffer cache. AWS Aurora seems to only add shiny new things to Postgres. And more.

    Again, none of this is quite enough to migrate off of it for an established system, but certainly enough to avoid it on a new project.

I also miss clustered indexes, datetimeoffest, plan caching and query hints from MSSQL.