Things I Hate About PostgreSQL (2013)

http://kupershmidt.org/pg/10_Things_I_Hate_About_PostgreSQL/#/

by subleq • 10 years ago

148 114 10 years ago

kupershmidt.org

altstar• 10 years ago

Just needs a [2013]

creshal• 10 years ago

What an awful format for slides.

divbit2• 10 years ago

Besides the fact that the font is really tiny, it's actually much nicer on phone than most of the "n things..." websites which seem to try and maximize clicks.

hibbelig2• 10 years ago

The font is _too_ tiny. I couldn't read the mono space parts.

mrob• 10 years ago

Disable CSS (in Firefox: View, Page Style, No Style) and the problem is solved.

the_duke• 10 years ago

I loved them, looks great, easy to read.

Liked the animations too. Not too much, but looks good.

coldtea11• 10 years ago

What exactly is awful about them?

obsurveyor• 10 years ago

It seems great for presenting them but after the fact:

Pollutes browser history(or if you click too fast, doesn't even have any), not convenient to browse at your own pace, no way to jump to a specific slide(visually)

The formatting is really good too and would probably work great as an article format but you're stuck reading tidbits, going back and forth.

kchoudhu• 10 years ago

10 slides in, and I realize that my back button is fucked.

Why do people do this?

CJefferson• 10 years ago

If I was doing slides like this, it would be because I was going to use them in a talk. Then I would want the back button to go back one slide.

If I then put them on the internet, I may not bother editing them to make the more "internet friendly".

saurik• 10 years ago

I personally would expect the back button to go back one slide, and would argue the opposite: that having the back button skip all the way to the previous web page is unintuitive and not "internet friendly". I mean, imagine if this slide deck were implemented using normal links: the fact that they are using some JavaScript-oriented feature to change the hash instead of changing the path shouldn't change the functionality, and implementing this without JavaScript would make it more clear that this is conceptually a page transition.

rix0r• 10 years ago

But how would you go forward in the first place? Not with the "Forward" button, because you haven't visited the page yet.

Instead, you press "Right" or "PgDn" or what have you. So I would expect the converse button ("Left" or "PgUp") to go back a slide as well (which it presumably does).

That leaves the browser's Back button to go back to the previous web page.

Everybody's happy!

Jgrubb• 10 years ago

It's reveal.js http://lab.hakim.se/reveal-js/#/, a pretty easy way to put presentations together. Just so you know where to direct the blame ;)

Kiro• 10 years ago

It's not messing up the back button for me.

rtpg• 10 years ago

I know a lot of people use Postgres (myself), and I was looking at the source recent, it seems pretty high quality. Makes it all the more surprising that there aren't really any performance tests.

Reviewing and pulling things in is always hard, though. In other software I highly recommend always breaking up big things into smaller changes if possible, but I don't know if that works well for the conservative release cycles for DBs.

Though maybe the conservative release cycle is what's wrong? Having to do a refactor to implement a feature doesn't mean that you need to do both at once.

nbevans• 10 years ago

Website is broken. UX fail.

coldtea11• 10 years ago

It's amazing that in 2016 people still don't know to press left and right arrows (or spacebar) in an online presentation.

It's the way ANY slideshow works, on desktop and online form. And it's a trivial thing to try, even when not told to. Not to mention by now there have been around 1000 such slideshows posted on HN.

wtbob4• 10 years ago

It's amazing that in 2016 people still don't know to press left and right arrows (or spacebar) in an online presentation.

It's amazing that in 2016 people still don't fall back gracefully in the absence of JavaScript and/or CSS.

kiwijamo• 10 years ago

I really like the slideshow UI. Anyone know which software was used to make this?

kawsper• 10 years ago

This is made with Reveal.js, but there is another one as well called Impress.js, they seem quite equal.

[0] https://github.com/hakimel/reveal.js/

[1] https://github.com/impress/impress.js/

alex-yo• 10 years ago

Yey, looks like people just watch presentations, not read it, that's why here is 1 comment about the content, 15 about how the presentation looks like :)

tsomctl• 10 years ago

I'm not even able to read it. I can't figure out how to go forward from the title page.

d33• 10 years ago

How about pressing space or right arrow key? If this doesn't work, make sure it's focused by clicking on a slide. Oh, and there are controls in bottom-right corner.

coldtea11• 10 years ago

Since time immemorial, the way to go forward in such pages is to press the left and right arrow buttons.

This has worked in 99.9999% of presentations uploaded on the internet and posted on HN.

It's also very intuitive to try, since this is how it is in any presentation desktop app too.

dorfsmay2• 10 years ago

Arrows! How do they work‽

wtbob4• 10 years ago

I can't read it, because it requires JavaScript to display images and text. Apparently HTML isn't good enough for that anymore.

qwertyuiop924• 10 years ago

I always enjoy good critique. There was a similarly excellent talk about the differences between Python and Ruby, which discussed the strengths and weaknesses of the design choices each made. It was fascinating. Unfortunately, I can't remember the link...

pmontra• 10 years ago

Maybe http://www.wikivs.com/wiki/Python_vs_Ruby or one of the links at the end of that page?

openfuture• 10 years ago

Extra relevant link cause when you try to go to 'main page' from that article you get a postgresql error!

stuaxo2• 10 years ago

The main thing I've hated about postgres over the years is pgadmin3. Haven't had to use it for a while but it was always easy to get it into a pickle in common situations, like losing the connection to the database.

icebraining• 10 years ago

Yeah, PGAdmin is fickle and not very intuitive. I've heard there are some decent alternatives, though, like Navicat.

dvdgsng• 10 years ago

DBeaver is pretty good.

ahachete2• 10 years ago

Have you tried pgadmin 4? It's a complete rewrite.

elmigranto3• 10 years ago

It looks pretty awkward to me. I don't get why they felt it's a good idea to do it in a browser with spaghetti-bowl of jQuery full of second-long animations.

stuaxo2• 10 years ago

I haven't had any postgres projects in the last year or so, so no - it does look a lot more functional than 3.

exceptione2• 10 years ago

The slides are from mid-2013, how many points are still valid? Has there been progress in the last 3 years?

koolba4• 10 years ago

The slides are from mid-2013, how many points are still valid? Has there been progress in the last 3 years?

From skimming through, I'd say the vast majority. Not sure about the PDF doc link issues as I only use the online HTML Docs but the overall generation of the docs is still a black art.

DoofusOfDeath• 10 years ago

I'm just trying to get started at PG contributing, and a lot of things regarding the process and regarding the strong emphasis on backwards compatibility ring true.

But my experience is very limited, so take that with a grain of salt.

scrollaway• 10 years ago

The google thing gets worse every release.

The Django project fixed it by adding canonical links to all the docs, see for example view-source:https://docs.djangoproject.com/en/1.9/ref/models/querysets/ (Has a <link rel="canonical" href="https://docs.djangoproject.com/en/1.10/ref/models/querysets/...)

The postgres project really needs to do that. It's a mess.

aninteger• 10 years ago

There's really only one thing I dislike about pgsql. It seems overly difficult to return two disjointed result sets from a stored procedure/function. This is fairly common and easy in MSSQL. It also is easy in MySQL. Something like this:

SELECT int_col_1, int_col_2 FROM table1

SELECT varchar_1, varchar_2, int_col_2 FROM table2

In pgsql if the columns are the same type and number then we can use a union, otherwise the suggested alternative seems to be to just make 2 queries.

koolba4• 10 years ago

In pgsql if the columns are the same type and number then we can use a union, otherwise the suggested alternative seems to be to just make 2 queries.

If the two commands have nothing to do with each other then yes that's usually the best option. That does open you up to understanding transaction semantics if you want to ensure both see exactly the same snapshot.

Another option is to use JSON as the great normalizer. Any row can be converted to JSON via row_to_json(...) or manually via the more low level functions. That allows you to "stack" multiple, distinct, JSON responses atop each other. Probably a bad idea 99% of the time to use something like that but it can come in handy that one time you want to jam things through in one query.

WayneBro4• 10 years ago

You didn't state a single reason why you think that grabbing multiple resultsets in a single trip to the database is a bad idea though...

The only real argument I've ever seen against it has to do with "Separation of Concerns". Some people don't want any logic in their database. However, there's never any reason why.

(I bet you've UPDATEd multiple tables in one query though.)

Reasons are often given, sure...but they're almost never based on that persons experience because PGSQL users don't have this feature. So, they'll never know just how awesome it is to have real stored procedures like TSQL has.

Anyway, it's not about "jamming" things into one query. It's about composability and PGSQL is lacking it.

WayneBro4• 10 years ago

This is my number one gripe about PGSQL. It's never had "real stored procedures", a feature which has been on the TODO list for a long, long time and nobody is even working on it. See Server-Side Languages/Implement stored procedures items and associated notes/threads here - http://wiki.postgresql.org/wiki/Todo

Beyond that, my other gripes about PGSQL are all surrounding the fact that it's simply not as polished or as widely used as SQL Server. I can't just drop PG in at some business site and expect the IT staff to be able to handle maintenance.

The Postgres GUI tools are extremely lackluster compared to the standard Microsoft SQL Server tools. Even the third party apps like Navicat are simply not as robust or as trustworthy as SQL Server Management Studio and the SQL Server Profiler. And there is literally nothing out that that compares with SQL Server Data Tools.

subleq• 10 years ago

What's the difference between "real" stored procedures and postgres functions?

Drdrdrq2• 10 years ago

I would imagine PG doesn't place much emphasis on GUI tools, being primarily hosted on Linux/BSD... Does your criticism apply to CLI tools too?

brightball2• 10 years ago

What is a good example of when you'd want to do that? I've been doing database work on the 4 majors for about 15 years and this is the first I've ever heard of somebody wanting to return two totally different result sets from a single procedure.

I have no issue with putting logic in your database. In many cases it's the ideal solution...but your example is something I've never even heard mentioned in 15 years much less advocated for or used as criticism for not being available.

donatj• 10 years ago

I know for a fact we have reports which do this. I didn't write them though, our old data guy did.

hanoz• 10 years ago

What is a good example of when you'd want to do that?

When you've got a long round trip.

redler• 10 years ago

One straightforward example would be feeding some kind of dashboard. Imagine a time-consuming query using a complex series of CTEs to build up or filter or reduce a very large set of rows, then running a bunch of "final" selects to transform and carve up that set in different ways to feed a bunch of tables and graphs. Obviously this could be done in various ways, but making one request to a procedure and receiving one response with multiple result sets can be a very pragmatic (and performant) approach.

sk5t• 10 years ago

One query, multiple result sets--so you can get a customer and the customer's orders in one shot without any join awkwardness. It's part of the jdbc spec and somewhat common in mssql land.

barrkel• 10 years ago

One place I worked used a disconnected data set model. The idea was a single stored procedure returned multiple result sets all relating to a single business entity; specifically, an insurance quote, along with all the drivers, vehicles, accidents, convictions, etc. The entity was locked by inserting a row in a table.

Thereafter, the application didn't communicate with the database until it was time to save the record. The disconnected data set was small enough to store in shared session store, or even in a cookie (encrypted, naturally).

This architecture had a number of interesting knock-on effects. The entire state of a client's conversation with the server was tiny and entirely encapsulated by this disconnected data set, so you could record and play back each request to recreate a bug.

It didn't have to use multiple result sets from the stored procedure, but it did save a bunch of round trips.

ahachete2• 10 years ago

You can write a plpgsql function that returns a setof refcursor (pointer to cursors). You can then iterate these cursors to retrieve the results from an arbitrary number of tables.

jokoon2• 10 years ago

I still don't understand database systems, how they work internally, and what problem they really solve.

It seems that new paradigms like R and RAM-only key values system are just simpler, faster and cheaper in programmer time. Loading everything in RAM and do a search seems like a huge saving of time and just works for most cases. Usually if you have more complex needs, you need to adapt your solution, and databases don't seem like a silver bullet.

Database queries seem like a solution to the problem of storing data on disk when RAM was too expensive. So today it's still used as some sort of standard, but when you can have 16GB of ram, I think you better teach yourself what sort of algorithm and data structures a database use to be faster, use the ones you like and need and solve your problem case by case.

The example of how reddit store its data is pretty demonstrative that ultimately, you should not let a database system do all the work. Databases are just a file format to me, but the way it tries to work for you at a lower level will respond to basic cases, but when you increase complexity it's not relevant anymore.

Especially today when you have big data and machine learning, everyone should just learn to understand data manipulation. Not saying to teach yourself C all over again, but having a decent idea of the math of what indexing is really about. Forcing yourself to use a database because the company always used it isn't appealing to me.

It's like one of those things when a programmer had an idea which is based on a constraint, everyone starts using it, several products are made, but nobody really remember the original idea of the inventor of that paradigm.

andybak2• 10 years ago

Time to wheel out pseudo-Greenspun again:

"Any sufficiently complicated NoSQL program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of a decent RDMS."

Or maybe: "Those who do not learn history are doomed to repeat it"

threeseed2• 10 years ago

I guess companies like Google, Facebook, Twitter, Apple, Microsoft, LinkedIn, eBay who run their entire core business on NoSQL databases don't know what they are doing.

coldtea11• 10 years ago

I still don't understand database systems, how they work internally, and what problem they really solve.

The use a formal, mathematical abstraction (relational algebra), even if somewhat crapily implemented by particular RDBMS, to facilitate saving data, relationships between data, and queries, while at the same time assuring certain properties (e.g. ACID) and doing so in a platform/programming language neutral format and with a consistent and industry standard query interface.

NoSQLs, key-stores and the like are not newer developments -- they predate databases. They were found to be a bad fit for what we wanted in enterprise use, and RDBS caught on.

For uses with huge data (Google and such scale) a denormalised approach might be more practical for performance reasons, in which case developers and ad-hoc programs get to re-implement all the functionality and assurances of a RDBMS in an ad-hoc way on top of rawer stores. (And all this could be alleviated with a properly optimised RDBMS for such purposes the still respects relational algebra).

In a conventional enterprise setting on the other hand, a DB trumps NoSQL etc solutions any day of the week.

Database queries seem like a solution to the problem of storing data on disk when RAM was too expensive. So today it's still used as some sort of standard, but when you can have 16GB of ram, I think you better teach yourself what sort of algorithm and data structures a database use to be faster, use the ones you like and need and solve your problem case by case.

The whole idea is to free the data from being tied to a particular language, data structures and algorithms.

Back in 2000-2007 it was all about XML, and how we should store data in XML format and get them back with XQUERY, XPATH and the like. A lot of people bought into the hype and the resulting products. Then it was about JSON -- and we now have JSON stores. In 10 years, it will be something else, again ad-hoc.

Meanwhile SQL has worked for the past 3+ decades, and is based on a solid mathematical abstraction (relational algebra).

It's like one of those things when a programmer had an idea which is based on a constraint, everyone starts using it, several products are made, but nobody really remember the original idea of the inventor of that paradigm.

You'd be surprised. Or rather you're exactly right -- few "really remember the original idea of the inventor of that paradigm", and that's why we're moving in circles with ad-hoc technologies re-implemented 30+ years after they were discarded. Or why people jumped enthusiastically to Mongo to return crying back to PostgreSQL.

Read a little around here for example:

http://www.dbdebunk.com/2015/07/the-sql-and-nosql-effects-wi...

http://www.allanalytics.com/author.asp?section_id=2386&doc_i...

http://www.dbdebunk.com/2015/11/moving-in-circles-sql-for-no...

threeseed2• 10 years ago

In a conventional enterprise setting on the other hand, a DB trumps NoSQL etc solutions any day of the week.

For a data warehouse yes people are still using RDBMS like Teradata.

But in enterprise environments most are now ingesting this data into Hadoop based data lakes and using NoSQL systems to drive the core analytics.

arielb1• 10 years ago

JSON is just as much rooted in math as SQL tables - it is `fix T = FiniteMap String T` plus a few primitive types, while SQL is `Collection (Set [String])` plus a few primitive types.

Of course, SQL has a nice efficiently-implementable algebra of set comprehensions, which may or may not be interesting for your particular use-case.

wiz21• 10 years ago

GB of RAM is fine until your database is one terabyte.

Also, RDBMS do constraint enforcement for you and that's absolutely critical when you work with any sufficiently big database (I work on a 100GB DB with a team of 6 people, changing here and there and I can't tell you how crucial the constraints are to maintain the data quality in face of bugs, misjudgment, etc.). And no, it's not for lack of testing. When you work on millions of super complex records, you always miss some corner cases (unless you're NASA and have a huge budget to test thoroughly)

known• 10 years ago

http://www.wikivs.com/wiki/MySQL_vs_PostgreSQL

fideloper• 10 years ago

I'd be all over pgsql if replication wasn't such a mess. Yes it works (presumably), but I can't find any useful (e.g. informative) information on a comparison between (the many??) methods to go about it and/or most modern way to accomplish it.

If anyone here knows of a good source, I'd love to see it :D (If you use the word "just" or link me the docs, you're dead to me).

epoch19702• 10 years ago

Why do you reject the documentation? It has exactly what you're asking for:

https://www.postgresql.org/docs/current/static/different-rep...

It describes the various methods that are available, it lists implementations of each, it explains the tradeoffs involved, and so on. Table 25-1 summarizes the information.

Regardless of the database system being used, replication is just inherently complex. There isn't really a one-size-fits-all solution. The method to use depends on the requirements and context of a given implementation.

exceptione2• 10 years ago

I think you might want to watch this tutorial from january 2015: https://www.youtube.com/watch?v=GobQw9LMEaw from Josh Berkus.

It starts with a comparison of the different ways available for replication.

lobster_johnson2• 10 years ago

Calling it a mess is unfair. It's actually quite straightforward, and the documentation (see sibling comment) guides you through the pros and cons.

For example, if you run with streaming replication — the recommended approach for most setups — then you can decide to enable WAL logs or not. If you only want replication, and not point-in-time recovery, then just running with WAL-less streaming replication is extremely simple and straightforward.

hyperpape3• 10 years ago

One thing that I really wish existed was a comprehensive guide to vacuuming, transaction id wraparound and similar issues. There have been a few posts recently that discussed problems that arise, but what I haven't seen is a sort of comprehensive "here are the issues that exist, here is what you must monitor in order to be safe" type of guide. The official docs are helpful, but fall short of that kind of guide, and none of the posts I've seen are really comprehensive.

Unfortunately, I'm pretty new to postgres and can't write it myself.

elmigranto3• 10 years ago

I found this to be great introductory that touches on all the major points to keep in mind with Postgres. It's pretty up-to-date too!

https://www.youtube.com/watch?v=knUitQQnpJo

It isn't quite what you ask for, but should be enough to get you high-level overview of major systems and contains solid practical advices (on vacuuming, mvcc, replication, backups, etc…), so you know what to google for deeper understanding.

hyperpape3• 10 years ago

Thanks! It's too long for me to watch right now, but I've saved it for the next time I can dedicate that much time to a video.

dorfsmay2• 10 years ago

I somewhat agree, and somewhat have the opposite view:

I love psql and tab completion, it's magic, in fact it spoiled me, I know have a hard time to work on any other DB.

Not mention in the article, but I love how the postgres dev keep up with modern SQL. Again it makes it really hard to go back on a SQL 92 compliant system.

Now, the vacuum business, that's horrible. I've run into so many case where "vacuum full" just solve the weirdest problems. One very recently where I use postgres as a queue (because it was easy and works across platform/clouds) nad it became slow and horrible even though I had dropped a bunch of schemas. "vacuum full;" oh wow!

The replications story is ugly. You can make it work, but it's literally a craft and you end up having to babysit it.

One the author missed, lots of weird performance issue, got my answer from the uber post. The rule #1 of adding indices is to only use column that you really really need, because otherwise you're going to slow down your writes. Well, it turns out not on postgres, all indices for the table you're writing to are being updated! I'm pretty sure very few people were aware of that before uber told us.

The more I use the postgres front end (psql, SQL) the more I love it, but the backend (performance, replication) is starting to taste more and more sour.

rpedela• 10 years ago

The index issue is being worked on now after the Uber blog post.

commitfest: https://commitfest.postgresql.org/10/775/

email thread: https://www.postgresql.org/message-id/CABOikdMNy6yowA%2BwTGK...

chucky_z• 10 years ago

Really? Coming from PGSQL to a MySQL-only shop made me really miss PGSQL's performance. Sure, MySQL is faster on `select pk from tbl where pk=1`, but the second you get into complicated joins, including subqueries, or doing any analytics the performance is very random.

With pgsql, I can get a clear concise explain and if I disagree with what's happening (because I know exactly what my hardware is capable of) I can tune any query to be decently performant.

With mysql, you get... I mean explain is ok, but I wouldn't put it above that. "EXPLAIN ANALYZE" is my gold standard forever and ever. I even liked it more than SQL Server's equivalent; which is also fantastic.

epoch19702• 10 years ago

MySQL's lack of CTEs is particularly annoying. Even SQLite has supported them for some time now!

I've seen this cause MySQL query authors to use various workarounds that end up impacting the query performance negatively.

paulddraper• 10 years ago

I've used PostgreSQL, SQL Server, and MySQL.

In my experience, MySQL had the worst query optimizer of the three. By A LOT. Basically, anything but a simple select could suck very unnecessarily. Even for simple selects, MySQL messes up.

I've fixed more than performance issue by changing SELECT * FROM users WHERE key1 = 0 OR key2 = 5 into two queries and concatenating the results.

garyclarke27• 10 years ago

Sublime Text works well for me as a Postgres query editor. Rock solid super fast, unlike all alternatives, (I've tried them all) except psql, which is solid but ugly. ST3 has for me a much nicer interface and has amazing search and replace ability, attractive themes, syntax highlighting from pg specific plugin. Remarkably it even copes with queries that return millions of rows. You can control it's behaviour with the same config options as psql, full feedback error messages, line numbers etc Easy to setup build system, see http://blog.code4hire.com/2014/04/Sublime-Text-psql-build-sy...

bdcravens• 10 years ago

Have you look at DataGrip? (https://www.jetbrains.com/datagrip/) Been using since it was in beta, and it handles SQL Server and Postgresql well. (haven't used it for other platforms yet)

jkmcf• 10 years ago

Oddly, I don't see anything about managing user permissions, access, and authorization. It's wicked arcane compared with every other DB out there. I believe one main reason MySQL caught on early with hosting providers was because of this.

lobster_johnson2• 10 years ago

That's odd, I feel the opposite. For years the way to create a user in MySQL was this:

    grant usage on *.* to 'bob'@'localhost'
      identified by 'itsasecret';

Meanwhile, PostgreSQL had the extremely straightforward "createuser" command line tool, and the "create user" SQL statement. (MySQL got "create user" and "alter user" around 2006 or so.)

Having to edit pg_hba.conf to allow network connections was always an annoyance for me, but at least the error message you get if it's set up wrong tells you to edit that file, which is also very straightforward and contains documentation out of the box.

Not allowing external access by default is arguably a security practice, though I always thought distro maintainers ought to have erred on the side of usability by enabling localhost access by default.

Things I Hate About PostgreSQL (2013)

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