MySQL 8.0 manual: "Queries that skip locked rows return an inconsistent view of the data. SKIP LOCKED is therefore not suitable for general transactional work. However, it may be used to avoid lock contention when multiple sessions access the same queue-like table."
Flattering (I wrote those words). Of course we borrow the SKIP LOCKED syntax from yet another database (though the idea is much older, under different names).
> MySQL is very popular. According to db-engines.com, it’s the second most popular SQL database overall. More importantly: it is, by a huge margin, the most popular free SQL database.
The second sentence is linked: https://db-engines.com/en/ranking
The third sentence refers to the same source.
That ranking site claims "The DB-Engines Ranking ranks database management systems according to their popularity." but then includes concepts such as "Number of mentions of the system on websites", "General interest in the system", and "Relevance in social networks" as part of the ranking (see https://db-engines.com/en/ranking_definition for details). In fact, the one thing one would typically consider to be "popularity" -- installed base size -- is not considered at all ("The DB-Engines Ranking does not measure the number of installations of the systems, or their use within IT systems."). In fact the paragraph from which I drew that quote highlights how ridiculous this site is: to understand that paragraph's use of the word "popular" you have to use the common definition, the definition they won't use in computing their so-called "popularity" ranking. This tells me that db-engine.com's ranking is not to be taken seriously.
As SQLite's page I pointed to claims, virtually every modern operating system and many popular programs come with at least one copy of SQLite. But then again, understanding the previous sentence requires using the word "popular" in a way that most people use that word most of the time, not the perverse way db-engines.com used the word. Put differently, Oracle, db-engines.com #1 pick, doesn't run on iOS, MacOS, GNU/Linux, and some variants of Windows. That means there are a considerable number of systems that host at least one copy of SQLite and will never host Oracle.
I find it very difficult to believe that there are more running or installed instances of Oracle on the world's computers than there are SQLite. The original article is plainly wrong. MySQL is nowhere nearly as "popular" as is claimed and the backing to believe otherwise hinges on a highly dubious source.
MySQL is under Oracle is one of the major concern, plus it's said to be good for less-write-more-read workload, which is fine.
PostgreSQL is more on the open source side, however bugs like this really concerns me: https://lwn.net/Articles/752063/ -- basically, PostgreSQL does not do its own DIO instead it depends on file system and it can lead to data corruption, and there is no quick fix...
tried to install mysql8.0 on ubuntu16.04 failed so far, need a vm to test it out sometime.
> Caution: Many operating systems and some disk hardware fool the flush-to-disk operation. They may tell mysqld that the flush has taken place, even though it has not. In this case, the durability of transactions is not guaranteed even with the setting 1, and in the worst case, a power outage can corrupt InnoDB data. Using a battery-backed disk cache in the SCSI disk controller or in the disk itself speeds up file flushes, and makes the operation safer. You can also try to disable the caching of disk writes in hardware caches.
It means that IF and only if, your storage is dying, you might learn about it later than you wish. In cases your storage is dying you are likely also going to observe problems that are outside of an fsync() not reporting an error when you'd like it to. As long as your storage hardware isn't broken, fsync still guarantees durability. Obviously it'd be better to get the error out ASAP.
On the plus side, I think this is great PR for FreeBSD (any filesystem) and ZFS (any OS).
One thing I'm curious about... MySQL still calls fsync() when you use O_DIRECT. See the warnings in the documentation about why O_DIRECT_NO_FSYNC is dangerous (to avoid loss of eg XFS meta-data, otherwise it might forget that a file was truncated or extended). I wonder if in some vanishingly rare failure mode you could lose data that way even with O_DIRECT.
That said, as several people have said, this is a very unlikely failure mode. When filesystems die, you know about it. The type of transient failure required to lose data this way is quite unlikely.
Error handling for a operating system is really complex stuff. I'm surprised that this isn't working properly, fsync is not about speed, but reliability. Userland applications expect it to work and behave as intended.
Without getting overly technical, MySQL's ease of use, wide supported drivers and toolsets, along with it's ubiquitous nature made me choose MySQL.
Also, almost everyone knows MySQL. Easy to find talent.
(Avoiding the technical reasons for brevity).
Also, so many big players use proven MySQL setups (Uber, Github, etc), that I feel like the scalability is there if needed.
EDIT: Does not seem fixed https://dev.mysql.com/doc/refman/8.0/en/temporary-table-prob...
I was working on script that builds a LEMP stack with Vagrant on a Debian box. And when the script was upgraded to use Debian Stretch, everything we did to customize MySQL configuration broke, and I spent many hours of anguish not knowing why.
Until I stumbled onto the fact that Debian decided that in version 9, they'd start installing MariaDB when you typed "apt-get install mysql-server". I cannot fully explain the anger I have for this dark pattern: When I say "install x", you should either install x or say you don't have it, not install a competitor you think is close enough.
We wanted to maintain both MySQL and MariaDB in Debian stable. However the Debian release team forced the removal of MySQL on the basis that MariaDB only would suffice. We disagreed with this but they overruled us.
mysql-server in Debian stable became a transitional package in Debian stable (only; this doesn't affect testing or unstable) in order to make the upgrade work correctly. It does force users with MySQL server to crossgrade to MariaDB server, and does lead to "mysql-server" being a misnomer in Debian stable.
"default-mysql-server" being MariaDB is also misleading, IMHO, but it's the best we could come up with because there isn't any other collective term that covers both MySQL and MariaDB.
We didn't want this, but it was forced upon us by the Debian release team. Sorry for the trouble. As others have said, we did our best to explain this in the release notes.
We continue to maintain both MySQL and MariaDB in Debian unstable, which remains free of this mess.
Oracle is litigious. This seems to be deep into "poke the bear" territory.
If I could still edit the comment, I would revise "burning white hot rage I have for Debian" to "burning white hot rage I have for the Debian release team". Alas I cannot. :(
Debian, as a project, appointed the release team and granted them the authority to make this decision. Therefore, IMHO, it's perfectly fair to attribute "Debian" to the decision. As long as you understand that it's not the Debian MySQL/MariaDB maintainers :)
I guess the fact that mariadb now owns the "mysql-server" package name is a side-effect of how apt manages upgrades and migrations. It's probably the best way to ensure existing users end up with a supported mysql-ish server after the upgrade, instead of being silently stranded on an obsolete debian8 package without receiving security updates.
mysql-server doesn't belong to MariaDB, they can't "own" it. Doesn't Oracle hold a trademark on it?
Whereas Windows apps tend to standalone, bringing with them any libraries they need, Debian tends to have one copy of each library, runtime, and so on. If you upgrade Debian, you upgrade way more than just the kernel, the gnu tools etc. You also upgrade, for example, the Python, the windowing system, the networking stack. Apps that rely on these must also be upgraded in order to work with the new versions of whatever other packages they rely on.
It’s a domino effect and it keeps on knocking right up to GIMP or, in this case, MySQL.
My answer doesn’t explain why this particular choice was made but I hope it shows how Debian can do that sort of thing whereas Windows wouldn’t.
These situations are rare, but it's not without precedent.
If I run "apt-get install mysql-server" and get something other than MySQL, we now have a trust issue: The Debian repository cannot be trusted.
mysql-server package installs mariadb so that they can handle upgrades gracefully in a way that won't leave existing users in cold.
They would choose to do it the way you said but then the people who are upgrading their systems would be annoyed instead of you. Tough choice but either way it's a minor annoyance to be honest.
Also it's not as if it isn't very clear what you're installing:
$ apt install mysql-server
The following NEW packages will be installed:
default-mysql-server galera-3 libdbd-mysql-perl libhtml-template-perl libterm-readkey-perl mariadb-client-10.1
mariadb-client-core-10.1 mariadb-common mariadb-server-10.1 mariadb-server-core-10.1 mysql-server
$ man mysql
MYSQL(1) MariaDB Database System MYSQL(1)
mysql - the MariaDB command-line tool
I certainly disagree that this qualifies as "very clear". The user asked to have mysql installed and the very first item on the list of stuff-to-be-installed is called "default-mysql-server". That certainly sounds like positive confirmation that you are indeed getting what you asked for.
Now, if you keep reading, you will see "mariadb-server-10.1" and stuff on that list, and if you also know two pieces of information (that mariadb is a fork of mysql, and that someone at Debian contemplated the idea of substituting one for the other), then you can see that you may have concluded the wrong thing and you can backtrack from there. Though really, at this point you still have conflicting information and it isn't conclusive.
So, I wouldn't say "very clear" is accurate. More like "possible to decipher if you have all the relevant context and are paying close attention".
As UIs go, this definitely violates the principle of least astonishment.
(though I don't buy this was an enough excuse for GP in this specific case because it becomes clear at the moment you run `mysql' command)
If Debian doesn't have a piece of software, it shouldn't update it. It should leave it alone.
(And bear in mind, I was working from a script, so unless I sit there reading every line while it builds the VM, all of this unauthorized breakage of my machine is silent and without consulting me.)
And of course, the response to "man mysql" makes no sense, because MariaDB is not MySQL.
> And of course, the response to "man mysql" makes no sense, because MariaDB is not MySQL.
MariaDB was supposed to be a drop-in replacement. This is why Debian (and other distros like Fedora) chose to name it and help transition of existing users. Distributions tried their best to make it as painless as possible. Sorry it wasn't the case for you but I guess it still helped more people than it hurt.
> (And bear in mind, I was working from a script, so unless I sit there reading every line while it builds the VM, all of this unauthorized breakage of my machine is silent and without consulting me.)
It was documented in Release Notes . You should've read it before upgrading your script. It is always a good idea to read it regardless of this specific issue.
Even if you didn't read release notes, banner text of `mysql' command makes it very clear it's MariaDB:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 32
Server version: 10.1.26-MariaDB-0+deb9u1 Debian 9.1
"Supposed to" is a key point here, cause it's not: Explain works different if you need a certain thread info, AFAIK no JSON data type, GIS functions are different, lots of subtle differences that will bite you in the arse if you presume it's exactly the same engine. And as the time goes by the list of differences is just growing.
It was allowed to stay in unstable:
However, the maintainers are uninterested in maintaining it there, since the release and security team have overrode them and forcibly removed it from stable.
Transitional packages are a source of confusion that are never fun, but this still sounds usually harrowing for dealing with the bumps of upgrading servers to a new OS major version. Just how rushed and close to the wire was your deployment?
Installing software that was not authorized on someone's machine is a serious security compromise.
Just learn from your mistakes and carry on.
This is a common mistake: you are conflating Linux and Debian. You don't have a Linux operating system, you have a Debian operating system and services & applications package (a "distribution") that happens to use the Linux kernel and other common parts associated (though in many cases not exclusively) with the Linux ecosystem.
MS wouldn't touch MySQL in an update because they never provided it for you. They might break it with changes that the upgrade makes and it isn't their responsibility not to (if you kept MySQL updated then you'd be fine as the maintainers would be aware of breaking changes in the OS and would have released updates to handle them ahead of time - but the onus here is on you to monitor that situation). They wouldn't change the operation of the DBMS they provide with the OS because there is no DBMS provided with the OS for them to break. A fairer comparison is MS updating IE with Windows upgrades, potentially breaking maintained web sites/apps that depend on non-standard and/or undefined behaviours in older versions of IE. Windows releases do often break other software, as do SQL Server release upgrades, as any major update of that sort does which is why thorough testing before releasing to production or otherwise mission-critical environments is essential.
> Installing software that was not authorized on someone's machine is a serious security compromise.
The release notes quite clearly state that it is going to happen. By installing the release you effectively authorised the process. And "serious security compromise" is hyperbole here IMO. A functionality compromise, yes, so effectively a DoS, but only for software more manually installed that is therefore not Debian's responsibility to keep compatibility with at all, and by installing the update without understanding it when the documentation was there to read you DoSed yourself.
While we are throwing around hyperbolic statements of blame: Not understanding the nature of the release update by at least reading through the release notes, and not testing an update in a pre-production environment, are both serious due diligence failures.
If the upgrade had left a (now unmaintained) mySQL install in-place with warnings in the documentation someone who didn't read that documentation wouldn't have seen the warnings any more than they would see the notes about the switch from mysql to mariadb so would have been left with a potentially insecure environment down the line as flaws are found by remain unpatched as Debian don't support mysql packages in that release.
If they had simply dropped the package your system would have been completely broken without manual intervention to install mariadb in its stead leaving your environment (more) broken.
The only way to keep everyone happy would be to keep maintaining both sets of packages, which, lo and behold, for all intents & purposes they do trough the LTS program: current old-stable is effectively supported until April 2020 so if you must keep mysql for compatibility purposes with software not provided as part of the distribution then you can keep using that for a while yet giving you nearly two more years to find a solution (waiting for that software made compatible with mariadb, finding an alternative to it, using mysql from another source (compiled locally or through a third party package repo, or moving to a Linux-based OS that does maintain mysql packages).
You could argue this was inevitable, but it was a product of the conditions at the time.
No, you installed their software on your machine without reading the release notes.
Percona has been a much better citizen with its fork.
Mariadb probably put in for the package name, tbh I can't be bothered to go find out, but I'd bet anything debian team didn't just arbitrarily make that call for users and ship it. 100% guarantee that.
I know your feeling though, that's the sort of thing that should be printing a warning or something when it happens.
In "Stretch", the default MySQL variant is now MariaDB. The replacement of packages for MySQL 5.5 or 5.6 by the MariaDB 10.1 variant will happen automatically upon upgrade.
Seems to me this is a non issue then.
I guess not everybody reads those, and I've already conceded that its something that ought to warrant a warning prompt or something.
But they didn't just change it for no reason.
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 32
Server version: 10.1.26-MariaDB-0+deb9u1 Debian 9.1
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.
$ mysql --version
mysql Ver 15.1 Distrib 10.1.26-MariaDB, for debian-linux-gnu (i686) using readline 5.2
This is not an accurate description of what happened. The information was in the release notes, which are several notches above EULAs for providing informed consent. Secondly, Debian doesn't install sotware, the user does. Debian helpfully provides the list of the packages and the versions before installing. There were no surprises here.
Additionally, contracts are not carte blanche to violate criminal law. To the extent that a contract provision would purport to allow violating a criminal law, it would be unenforceable.
You are filled with hatred and rage towards a project and you wish they'd be be sued to death by Oracle because of a minor package naming issue?
Same as in Debian. mysql-server is a transitional package which ends up installing mariadb-server package at the end.
Several other documented configurations for DB2 components didnt work and after months of work with IBM support were later deemed unsupported. This was circa 2002-2004 while I was an intern. Havent used DB2 since, so dont know if the situation has changed.
I think if someone came along and fixed these major issues and gave it a modern syntax without significantly degrading performance, it would be sufficiently different that the XKCD "competing standards" meme would not apply.
I would love to hear from someone with database specialization.
> I believe the main reasons are a lack of knowledge and interest among developers along with poor support for modern SQL in database products.
However, it IS getting better at the moment. Have you seen the "New SQL" systems that implement window functions? MySQL is finally adding those features and MariaDB picks other features from the standard.
There is movement.
I'll just keep on making my comparison matrices to make the differences visible. This will (hopefully) increase developers interest, which is basically a market demand. Vendors listen to market demand. evil grin
SQL:2003 added XML functions
SQL:2006 more XML!
My guess it's not so much "willy-nilly" but more a sign of "what was popular."
SQL:2003 added Window Functions, standardized sequences, and columns with auto-generated values
SQL:2006 okay, this one sounds like it was mostly about XML, but a lot of the functionality that went into dealing with structured content is what made the JSON support workable.
SQL:2008 this gave us the MERGE version of upsert, instead of triggers (which apply to views, and are a powerful way to deal with backwards compatibility)
SQL:2016 LISTAGG (super powerful), Row Pattern Recognition (a lot more intuitive that comparable uses of WINDOW functions), standardized date/time parsing, and polymorphic table functions (which you can kinda see in, for example, BigQuery's legacy table wildcard functions)
That's a heckuva deep cut.
I wonder why/how MySQL got so popular, when in my head the go-to is Postgres (perhaps because I worked on Django/Rails stuff early on). Is it because of Oracle and their marketing/sales work?
MySQL's popularity long predates the Oracle acquisition. MySQL got popular because it was usually available (alongside PHP) on shared hosting and had very fast read performances (using the default MyISAM storage, at the cost of write performances or actually caring about your data). What with the web being front-loaded on read, that made it a pretty good fit.
Meanwhile historically postgres was byzantine to set up and slow. It cared much more for your data and had plenty of features (custom types! procedural languages! transactional DDL!), but it didn't really work OOTB (still doesn't, IIRC the base configuration still assumes rotating rust and 128MB RAM or some shit) and wasn't available on most hosting platforms, especially not the really cheap shared hosts.
Also while Django defaulted to postgres, I'm pretty sure Rails used to kinda-sorta default to mysql (I'm talking 10 years back, many plugins/extensions didn't work properly on pg).
It's because the two projects had different starting goals, and thus attracted different audiences. MySQL was designed to be small and fast, while sacrificing consistency and integrity. Postgres was intended as an enterprise class DB from day one, with the expected robustness, integrity, and feature set. It led MySQL on features for many years, but lagged on speed.
During the .COM boom of the 90's, the flurry of startups cared more about speed and ease-of-use, and were willing to sacrifice consistency. Thus it became the default choice for most open-source projects and web development. Because of this, a whole ecosystem of support and tooling developed around MySQL, which reinforced the industry trend.
As to performance, Postgres has long since bridged that gap. As to ease of setup/config - Postgres was never difficult in the first place. The perceived complexity was due to its more robust feature set and security model. There was certainly more to learn, but honestly, it was never so terribly difficult as some people then and now seem to view it.
It provided fast relational SQL database for the early web application stack without any concern of maintaining ACID (Atomicity, Consistency, Isolation, Durability) that "real" databases like Postgres providied. It had slight speed advantage and that was enough to turn the scale against Postgres.
MySQL was demonstration of Worse Is Better in the database world.
Yep, over and over again, "worse is better" proves itself as the all-important software mantra. Get that flimsy "database" out the door and loop back around to fix the "eats data" bugs 5+ years later.
The key to adoption seems to be to pinpoint something that people really want ("super fast 'SQL database' that I can run virtually for free" c. 1999), rush out a one-fifth-working version of the headliner features and pretend like it's all well and good, and then work to spread that solution as widely as possible.
Once you get the momentum, it's impossible to stop, and someone like Sun swings by to ask if you'd mind taking a billion dollars off their hands.
Not sure it beats PHP in being worse. But at least both got substantially better with recent versions.
The MS-DOS of databases
Eventually Postgres got fast enough and MySQL got reliable enough, which has made the distinction between them somewhat fuzzier today. But by then MySQL had become the standard database offered by umpty zillion web hosts, and ubiquity is a hard position to dislodge someone from.
MySQL still doesn't support nested DDL's, and this has caused me extreme amounts of pain in old projects where consistency was expected and we did not receive it on crucial payment processing.
My experience recently and historically has been the exact opposite. Postgres seems to blow up in more mysterious and hair-yankingly frustrating ways than MySQL does. "Why Uber Engineering moved from Postgres to MySQL" echos a lot of the issues I've had with Postgres in large production environments.
this is very scary, if not fatally scary.
Things might have changed now for Postgres.
This, plus strong consistency to prevent shooting yourself in the foot, is valuable for 99% of use cases where you don't need insane web scale.
Edit: Added more context
MySQL was the M in the LAMP stack, and was installed on many linux distros by default.
Except WITH [RECURSIVE] which is in SQLite since early 2014. Damn, I forgot to use that trivia in my MySQL bashing... ;)
Other than that, I met Richard Hipp in person some years back. He is a VERY pragmatic guy. I wrote an article about it:
* If you have pre-5.6.4 date/time columns in your table and perform any kind of ALTER TABLE statement on that table (even one that doesn't involve the date/time columns), it will TAKE A TABLE LOCK AND REWRITE YOUR ENTIRE TABLE to upgrade to the new date/time types. In other words, your carefully-crafted online DDL statement will become fully offline and blocking for the entirety of the operation. To add insult to injury, the full table upgrade was UNAVOIDABLE until 5.6.24 when an option (still defaulted to off!) was added to decline the automatic upgrade of date/time columns. If you couldn't upgrade to 5.6.24, you had two choices with any table with pre-5.6.4 types: make no DDL changes of any kind to it or accept downtime while the full table rewrite was performed. To be as fair as possible, this is documented in the MySQL docs, but it is mind-blowing to me that any database team would release this behavior into production. In other words, in what world is the upgrade of date/time types to add a bit more fractional precision so important that all online DDL operations on that table will be silently, automatically, and unavoidably converted to offline operations in order to perform the upgrade? To me, this is indicative of the same mindset that released MySQL for so many years with the unsafe and silent downgrading of data as the default mode of operation.
* Dropping a table takes a global lock that prevents the execution of ANY QUERY until the underlying files for the table are removed from the filesystem. Under many circumstances, this would go unnoticed, but I experienced a 7-minute production outage when I dropped a 700GB table that was no longer used. Apparently, this delay is due to the time it takes the underlying Linux filesystems to delete the large table file. This was an RDS instance, so I had no visibility into the filesystem used and it was probably exacerbated by the EBS backing for the RDS instance, but still, what database takes out a GLOBAL LOCK TO DROP A TABLE? After the incident, I googled for and found this description of the problem (https://www.percona.com/blog/2009/06/16/slow-drop-table/) which isn't well-documented. It's almost as if you have to anticipate every possible way in which MySQL could screw you and then google for it if you want to avoid production downtime.
I've been using Postgres very consistently for the past half decade (as a dev, not a DBA) and it's had a `GROUP BY` and `WHERE` clause for at least as long.
I'm not totally sure what "base table `UNIQUE`" is supposed to mean in this context, but if it's just the bare `UNIQUE` constraint, Postgres has also had that for a long, long while.
E.g. SELECT countries.code, countries.name, count(*) FROM countries JOIN countries_languages as co_lang on co_lang.country_code = countries.code GROUP BY countries.code
This isn't supported by Postgres, because countries.name is not in the group by clause, on the other hand it does make sense, because code will be unique in the countries table, so there will always be only one name for a given code.
(see https://mysqlserverteam.com/mysql-5-7-only_full_group_by-imp... which is also linked from the original article)
This aspect of the original article is really talking about how MySQL decided to implement a more up-to-date version of the spec that many competitors when they finally addresses their deficiency (as well they should, finally being SQL-92 compliant in the 2010's wouldn't really be anything to boast about).
The first feature matrix you see is about checking of functional dependencies.
For example, PostgreSQL doesn't see the functional dependency between the columns ID and MA in the result of this query.
, max(a) ma
GROUP BY id
SELECT COUNT(*) cnt
FROM (SELECT id
, max(a) ma
GROUP BY id) x
GROUP BY id
postgres=# create table func_test ( id int primary key, data text );
postgres=# insert into func_test values ( 1, 'josh' ), ( 2, 'markus' );
INSERT 0 2
postgres=# select id, data from func_test group by id;
id | data
2 | markus
1 | josh
> 4.24.13 Known functional dependencies in the result of a <group by clause>
Not that this is about the result of a <group by clause>
edit: The matrix I have in the article is not complete. I've just picked a few examples from the standard and checked them to get an overview. I guess the fact that PostgreSQL supports some of them but MySQL more of them is well represented in the matrix.
The full text is below. I'm happy to correct, when I'm interpreting this wrong (which is perfectly possible).
Let T1 be the table that is the operand of the <group by clause>, and let R be the result of the <group by clause>. Let G be the set of columns specified by the <grouping column reference list> of the <group by clause>, after
applying all syntactic transformations to eliminate ROLLUP, CUBE, and GROUPING SETS.
The columns of R are the columns of G, with an additional column CI, whose value in any particular row of R somehow denotes the subset of rows of T1 that is associated with the combined value of the columns of G in that row.
If every element of G is a column reference to a known not null column, then G is a BUC-set of R. If G is a subset of a BPK-set of columns of T1, then G is a BPK-set of R.
G ↦ CI is a known functional dependency in R.
, max(a) ma
, count(*) Cnt
GROUP BY id
But then I remember this is the database that lied (lies?) about ACID transactions, and had no problems storing non-existent dates in a DateTime-column because its creators considered ensuring data-integrity and consistency “the job of the application layer” (which back then often was PHP).
Nothing should really surprise me.
What's that in reference to? The article explains that MySQL implemented group by using a newer standard than many competitors did, by looking at functional dependencies. Not exactly novel, but good for MySQL, they decided to go beyond the competition when finally catching up on this particular feature.
There are, of course, many other problems with MySQL (as you allude to), such as silently ignoring CHECK constraints, but that doesn't seem to make sense as what you were referring to in context of what they consider novel.
Time moves on. The Innodb storage engine has had ACID transactions for over a decade.
> no problems storing non-existent dates in a DateTime-column
PostgreSQL checks date formats, but updating (or not updating) timezone databases would affect validity. So it's not as simple an issue as you make it to be.
But there is a patch pending for this. Not sure if this gonna be included in 11.
This is how standard SQL JSON_OBJECTAGG works:
It can actually do much more:
<JSON object aggregate constructor> ::=
JSON_OBJECTAGG <left paren>
<JSON name and value>
[ <JSON constructor null clause> ]
[ <JSON key uniqueness constraint> ]
[ <JSON output clause> ]
This free technical report of ISO has some examples: http://standards.iso.org/ittf/PubliclyAvailableStandards/c06...
Is it really that different to not even warrant a note in the table?
Clearly you know better than I do, but the big red X surprised me as the fantastic JSON support is one of the reasons why I tend to reach for Postgres so often over other DB engines.
There is nothing against using non-standard functionality in that case. In this particular case. PostgreSQL got JSON support (~2012?) long before it was added to the standard (2016). Obviously, their JSON functions differ from the standard (as they didn't lobby their functions into the standard).
However, slowly but surely database will add the standard functionality, which makes life easier.
Having that said, the standard JSON_OBJECTAGG is more powerful as it gives you control over null handling (NULL ON NULL -vs- ABSENT ON NULL) and allows checking for duplicate keys ([(WITH|WITHOUT) UNIQUE KEYS]).