Ask HN: PostgreSQL or MySQL?

Do you know if it is still happening in the newer versions (v3.6+)? If so, could you point to the references? I would love to learn more about the data loss issue.

That is simply not correct. Please understand that I worked on MySQL at Facebook, so I know what I'm talking about here :)

Facebook developed an entirely new MySQL storage engine (MyRocks, which is a RocksDB-backed engine for MySQL) and then migrated their largest sharded tiers to it. This is basically just as much work as developing a new database from scratch, i.e. more work than something like migrating to Postgres. This completely debunks the "changing is basically impractical" claim.

And while Facebook's primary db tier (UDB) does have a restricted API / access pattern, calling it a "key-value store" is a gross oversimplification at best, or completely inaccurate at worst. Range scans are absolutely core to the UDB access pattern, for starters.

Many other social networks are also built on MySQL (linkedin, pinterest, tumblr; and several in China) or previously used MySQL before moving to a custom in-house db (twitter). I think reddit and instagram are the only two using pg? And I recall parts of instagram were being moved to mysql, although I'm way out-of-date on whatever happened there.

HN discussion on this: https://news.ycombinator.com/item?id=12166585

> I personally believe that great documentation was a big reason for PHP's success in the early days.

I agree. The culture of user-submitted comments with helpful examples and clarifications on each documentation page was a big part of that, too.

To echo a few other commenters here, a major point of consideration is your team's experience and broader technical network. Generally speaking, either Postgres or MySQL is likely fine for most applications. But you'll have a better time with whichever one you can most smoothly build on, operate, and hire for.

Separate from that, and with the disclaimer that my career has been heavily MySQL-oriented, although I try to provide a balanced perspective:

MySQL can be a good choice for OLTP-heavy workloads, such as a high volume of relatively straightforward queries. It also supports a very wide variety of replication options. In some aspects, MySQL is simpler to operate than pg. (This can be a point of contention, as MySQL is more idiosyncratic and this leads to some land-mines that are well-known to the community, but unclear from the manual alone.)

At this point there are also many hundreds (thousands?) of engineers and DBAs worldwide who have extensive experience working on massive-scale MySQL deployments. This may or may not be relevant to your project, depending what you're building and its eventual best-case size.

MySQL is admittedly less "batteries included". Although MySQL/InnoDB does support things like windowing functions, fulltext, geospatial, etc they're not necessarily a best-in-class implementation yet. In a MySQL shop, if you need OLAP, you're better off doing ETL into a separate column store or Hadoop cluster; if you need fulltext search, you're better off using a separate search index system like Solr; etc. Depending on your point-of-view, this approach is either "more UNIXy" or a major operational headache, or both :)

Meanwhile Postgres may be a better choice if you want to handle a bunch of things using a single piece of software: mixed OLTP + OLAP workloads, fulltext search, geospatial. It also has some interesting indexing features MySQL lacks, such as partial indexes, and ability to index an entire nested JSON structure in a single index.

Postgres gets major points for having a true open source development model, cleaner core code, better adherence to SQL standards, etc. Conceptually, it is very well-aligned with the textbook description of a relational database. Its adherents love it, sometimes fanatically so, which can be a mixed bag to outsiders. I sometimes feel parallels to the Mac user community in the late 90s/early 00s: it's probably a better choice for many use-cases, but personally I raise an eyebrow to suggestions that it's the universal best choice for all possible situations.