Overall, I agree with the sentiment of your comment, but the assertion that MySQL isn’t a serious database is just flat out wrong.
The questions I usually ask myself when evaluating database solutions is:
* Does it accept invalid data?
* Does it change data on error?
* Does the query planner change drastically between minor versions?
* How strong is transaction isolation? can I create constraints, columns or tables in a transaction?
* Does it scale vertically above 40~ CPU threads and 1M IOPS?
The answer to all these questions, for MySQL is "No". You could argue the value of some of them, but a lot of them highlight architectural or development procedural misgivings.
Most companies are not alive "because they chose mysql over something else" they're alive because they have "good enough" tech to get the job done. The job that they're trying to accomplish is the thing that makes them successful.
Uber isn't super huge because it used a specific database technology. It's huge because it's good at marketing, it's providing some value to people.
If it silently corrupts data over years and gets discovered much later. (As was the case with my previous company, an e-commerce retailer that lost large chunks of order history)
> How do you know that similar or worse problems did not exist in alternative solutions at the time it was implemented?
Because I've been working on database solutions for over 10 years, there are problems in other software but I consider data loss to be worse than any of them. For example the autovacuum in postgresql 8.3 and before was mostly garbage which ended up bloating highly transactional databases. But deleting data when you fail a constraint is worse.
Still, if you are making choices for yourself, you don't choose mediocrity and hope to muddle through: you choose excellence. Choosing MySQL isn't choosing excellence.
Do you have objective or quantifiable data and references upon which your opinion is based, _and_ is universally applicable to any arbitrary problem that a SQL database might be an appropriate solution for?
I do not think MySQL is a technological debt as in 80% startups moving to the different solution is cheap and non-problematic. The LAMP is good enough and quickest/cheapest for the majority of tech companies.
You can solve issues in your application if you know there will be issues like these, knowing the pitfalls and drawbacks of a technology is certainly noble- but if you do then why not choose something that follows principle of least surprise. (There might be reasons).
I would never claim that you should move everything from MySQL if you use it. However if you care about data consistency ensure that you change the defaults, engage strict mode, ensure that your application has no bugs in handling data.
This is actually hard to do correctly, it's overhead in development that you shouldn't be caring about. Just choose something that has sane error conditions and the problem vanishes.
To start with, this is still true today: https://vimeo.com/43536445 Despite being 6 years old, strict mode is still required.
Anything prior to MySQL 5.7 will accept "0000-00-00 00:00:00" as a valid date, 5.7 will not (which is sane) however this means migrating from 5.6 -> 5.7 just got a little harder.
In fact it wouldn't validate /any/ date so it would assume every year was a leap year and febuary always had 29 days.
Regarding the query planner: https://bugs.mysql.com/bug.php?id=74602 This affected my prod mysql/zabbix installation https://support.zabbix.com/browse/ZBX-10652
Regarding performance: This is what I found from my own experience: I was given the task of testing the limits of MySQL, MySQL was the chosen technology and I was no involved in making that decision so- whatever. We were given 10 servers, with 40 cores (2014-2015~) 128G of DDR3/ECC and 8 SATA SSDs in RAID-0 with 1G of RAID cache for write-back. We managed to get MySQL to bottleneck pretty quickly, our queries involved a lot of binary data so we should have been raw IOPS bound, but we weren't we were memory bound. So we replaced the memory allocator with a faster one (jemalloc) and we get a 30% performance improvement. We suspected that the kernel sockets implementation was slowing us down so we compiled a custom "fastsockets" linux kernel. The improvement was around 4%, but we were bottlenecked on memory. After doing a full trace of what MySQL was doing we saw that InnoDB was spinning on a lock quite a lot. I asked if we could try other SQL solutions (MSSQL/PostgreSQL) Postgresql was first chosen because we could just install it, no license and no OS change... it was twice as fast as the optimised MySQL installation out of the box with a stock CentOS6 kernel.
We never even bothered testing MSSQL because PostgreSQL met our performance targets, we were now IOPS bound.
-- More anecdatum:
Regarding data consistency we (tried) to migrate to postgresql for performance reasons in 2014 (my previous company), and failed because MySQL had been corrupting our data very slowly and silently for many years (corrupting meaning not honouring NOT NULL, not honouring type safety, allowing invalid dates, inserting data on error) So far in that actually reimporting the output of `mysqldump` would not work.
Isn't it? I thought that today()-(2018 years, 4 months and 10 days) would be approximately that date? Maybe you prefer +0000 vs just 0000?
'ISO 8601 prescribes, as a minimum, a four-digit year [YYYY] to avoid the year 2000 problem. It therefore represents years from 0000 to 9999, year 0000 being equal to 1 BC and all others AD. However, years prior to 1583 are not automatically allowed by the standard. Instead "values in the range [0000] through [1582] shall only be used by mutual agreement of the partners in information interchange."
To represent years before 0000 or after 9999, the standard also permits the expansion of the year representation but only by prior agreement between the sender and the receiver.[19] An expanded year representation [±YYYYY] must have an agreed-upon number of extra year digits beyond the four-digit minimum, and it must be prefixed with a + or − sign[20] instead of the more common AD/BC (or CE/BCE) notation; by convention 1 BC is labelled +0000, 2 BC is labeled −0001, and so on.'
https://en.m.wikipedia.org/wiki/ISO_8601
Now, if mysql accept, but can't store such a date, I understand that it's a problem.