One of the questions that gets asked quite a lot, is: how can you use variables in your queries? Other databases have them, does PostgreSQL?
Actually the answer is “no". But, it is actually very easy to work around, and what's more important – quite often, what you need are not variables in queries, but rather variables in client. What does it mean? Let's see.
On 2nd of February, Tom Lane committed patch:
Create a psql command \gset to store query results into psql variables. This eases manipulation of query results in psql scripts. Pavel Stehule, reviewed by Piyush Newe, Shigeru Hanada, and Tom Lane
So, lately I have been thinking about integrating explain.depesz.com with psql. Currently, you have to run explain, copy the output, switch to webbrowser, go to explain.depesz.coma> site, paste output, click submit. It's not that it's a lot of work, but it can be simplified.
Continue reading Adding plans to explain.depesz.com from your psql
So, you just installed your PostgreSQL, and you have no idea how to use it – there is no icon in the menu of your OS, so how can you use it? Well, with the dreadful command line.
Of course – some people will never get used to textual programs. They need a GUI. That's fine. Not understandable for me, but who am I to judge. But knowing at least a basic things about standard command line tools for PostgreSQL can save you a lot of headache in some cases. Plus – you always have them so these are treated as default programs to use.
Continue reading Command line tools? In XXI century? No way! Yes way!
I use VIM. For more or less everything. Including writing blogposts.
Usually, when I was working on blogpost about PostgreSQL, I would write an sql file, switch to another console with psql running, run \i, get output, and then copy/paste the results to my blogpost in another vim.
It worked, but wasn't really nice.
Today, I realized that I can do something much smarter.
I can just type in Vim, and then pass the data to psql, using simple “visual mapping":
:vmap R :!psql -e<enter>
How does it work? When I'm in Vim, and I select (visual) some text, I press shift-R, and the selected blob is sent to psql.
Of course – psql has to know which database to connect to, as which user, and so on, but this is handled by setting PG* environment variables before running Vim.
Thanks to “-e" option, I get all the queries printed back to me, so I don't lose them from my text file.
It works just great.
While I didn't show it in the ascii cast, I can of course also run in this way multiple queries, use transactions, and everything else. The only problem might be that every such run is executed in new psql, which means that you don't have single session.
But, that doesn't seem to be big problem (at least for me).
It would be nice to have vim as full blown sql client, and I think it's perfectly possible, but I just don't care enough to spend time writing necessary scripts.
Recent release of new versions of PostgreSQL suggests that you do reindex of all indexes. But this will take a while, and since we don't actually have ‘REINDEX CONCURRENTLY' command – it's a bit tricky.
So, since I will be doing this on several databases, decided to write a script that will handle the work for me.
Continue reading Concurrent REINDEX of all indexes in database
I'd like to announce start of new project for PostgreSQL admins – Curo.
Yesterday I talked a bit with David Fetter about improvements in psql. We both would like to get proper stored procedures (with multiple result sets, and transaction control), but since this seems to be too complicated, I thought about what I'd like to have added to psql.
On 6th of July, Robert Haas committed patch:
Add \ir command to psql. \ir is short for "include relative"; when used from a script, the supplied pathname will be interpreted relative to the input file, rather than to the current working directory. Gurjeet Singh, reviewed by Josh Kupershmidt, with substantial further cleanup by me.
On 20th of July, Robert Haas committed (and later committed change to it) patch which adds another \* command to psql:
Log Message: ----------- Add \conninfo command to psql, to show current connection info. David Christensen. Reviewed by Steve Singer. Some further changes by me.