Tuesday, 27 August 2013

PostgreSQL proper installation

Recently at work, i got assigned to upgrade some (about 10)
postgres 8.1.x to 9, I always liked compiling basically because I like the flexibility that compile offers, and thats what i proposed to the guys that are in charge of the project. They gave me a test system (vm) to play with, in all fairness they were a bit skeptical with the idea of compiling the rdbms. Mostly for reliability issues (don't ask me why). I explained that upgrading from source would be much easier later on and that the last year PostgreSQL developers are doing so much work that it cannot be ignored (pg_basebackup for example).Since the latest centos package was 9.1.x they agreed and i started working.
PostgreSQL is so easy to compile, no strange dependencies not many libraries needed. and about these reliability concerns ? Because developers are so neat, and i quote from
http://www.postgresql.org/support/versioning

"While upgrades always have some risk, PostgreSQL minor releases fix only frequently-encountered security and data corruption bugs to reduce the risk of upgrading. The community considers not upgrading to be riskier than upgrading."
 


You should never find an unexpected change that breaks an application in a minor PostgreSQL upgrade. Bug, security, and corruption fixes are always done in a way that minimizes the odds of introducing an externally visible behavior change, and if that's not possible, the reason why and the suggested workarounds will be detailed in the release notes. What you will find is that some subtle problems, resulting from resolved bugs, can clear up even after a minor version update. It's not uncommon to discover a report of a problem to one of the PostgreSQL mailing lists is resolved in the latest minor version update compatible with that installation, and upgrading to that version is all that's needed to make the issue go away.

so don't be afraid to upgrade , DO IT

If you want to compile postgres you will need (except from the basic development tools) the following 2 libraries :

zlib1g-dev (compression library needed if you want to compress directly from postgres, pg_dump -Z for example)

libreadline6-dev (used by the client to support history on psql)

You could call both these libraries optional and you actually can compile postgres without them, but meh , don't do that...

Other than that its pretty much straight forward,
untar
./configure
make
make install (check the documentation for extra flags , change of prefix etc)

postgres will install the binaries by default in /usr/local/pgsql/
Packages from the other hand will install in /usr/bin (MEGA SUPER LAME)

SO ! lets see the current situation. I inherited a postgresql server that had a package installation, the binaries located in /usr/bin and postgres home in /var/lib.
If it was compiled i could go to /usr/local/pgsql , rename it to /usr/local/pgsql8 remove it from the path and let it be, but yeah, i couldn't do that, i fixed the path, put /usr/local/pgsql before /usr/bin so the first postgres binaries in path order were 9's so i was ok. But still ! the packages tend to inter-grade deep into the OS making any other option (like running 2 postgres servers at the same time) more difficult that it should be.

I like adding some of the contrib packages into postgres , for logging, monitoring and tuning reasons pg_buffercache, pgbench, pg_stat_statements, pg_freespacemap are some examples.
In a compiled environment there is nothing easier than that, nothing extra to download not much to do, just compile the contrib module and add it to the database with CREATE EXTENSION.
Now lets say that after a while a new release of postgres comes and i wanna upgrade to that just because i want to stay current or because a new wow feature was added or a bug was resolved, all i have to do is compile the new version (assuming its a minor release) replace the binaries and restart the server. Package installed postgres server would have to wait till the distribution released a new package of the new server usually a few versions behind current, which means what ? a month after the release date? maybe more!?

Basically the only thing that i can imagine being easier with a package installation are the init scripts, and yeah , ok i don't think that is a huge pro comparing to a compiled version.

SO my suggestion is , compile the damn thing.. COMPILE !


Thanks for reading
-Vasilis

4 comments:

  1. Why not just use http://yum.postgresql.org/? It has the latest versions of Postgres and nothing is easier for upgrade than running 'yum update'.

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  2. it doesn't have anything to do with the version, postgres provides packages for all major distributions with every release. I just believe that’s its much more organized to install the binaries under a custom path and have them separated from the rest of the OS

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  3. > /usr/local/pgsql

    Isn't /usr/local supposed to have the same layout as /usr? -- last I checked, "all files for an app in a single folder" installs would be in /opt


    > the packages tend to inter-grade deep into the OS making any other option (like running 2 postgres servers at the same time) more difficult that it should be.

    Debian seems to handle it quite nicely, data stored in "/var/lib/postgres/9.2/main" etc, so you can have multiple versions at once, and migrate data between them easily (running several separate instances of the same version is hard, but I can't think why you'd do that)

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  4. /opt is a relatively recent dir that some like, some don't , personally i just want to keep my installation on a directory that i can separate different versions, /opt works fine for me.

    Not everyone has debian, in fact most installations are some kind of RHEL for commercial support etc, and that's exactly why i made this post and that's why i almost always install with compile , its distribution independent and whatever path i choose to install to , I can.

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