From: | Ian Lawrence Barwick <barwick(at)gmail(dot)com> |
---|---|
To: | Aleksey Tsalolikhin <atsaloli(dot)tech(at)gmail(dot)com> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Graphing query results from within psql. |
Date: | 2013-02-14 02:36:35 |
Message-ID: | CAB8KJ=j5J8w22=SY1FgRWgkREizYEjAOsK5j+K20iS49+gS5_Q@mail.gmail.com |
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Lists: | pgsql-general |
2013/2/14 Aleksey Tsalolikhin <atsaloli(dot)tech(at)gmail(dot)com>:
> Below is an example of feeding query output to gnuplot without leaving
psql.
> I'd like to call it as "select graph(select * from example)", just for
fun.
> What do I need to learn to do that, please? Can I create a function that
> uses "\o"? I think not, because a function runs server-side and \o is a
> client side feature.
You are correct, it is not possible for a backend function to interact
directly with psql. You'd need to create a function in PL/Perl etc.,
and would have to have gnuplot available on the DB server.
What you could do is create a small psql script along these lines:
barwick(at)localhost:~$ cat tmp/plot.psql
\set QUIET yes
\t\a\f ' '
\unset QUIET
\o | /usr/bin/gnuplot
select 'set title "My Graph"; set terminal dumb 78 24; set key off; set
ylabel "Time"; set xlabel "Servers";' || 'plot ''-'' with lines;' ;
:plot_query;
\set QUIET yes
\t\a\f
\unset QUIET
\o
barwick(at)localhost:~$ psql -U postgres testdb
psql (9.2.3)
Type "help" for help.
testdb=# \set plot_query 'SELECT * FROM plot'
testdb=# \i tmp/plot.psql
My Graph
4 ++---------+-----------+----------+----------+-----------+---------**
+ + + + + + **** +
| **** |
3.5 ++ **** ++
| **** |
| **** |
3 ++ **** ++
| **** |
2.5 ++ ***** ++
| **** |
| **** |
2 ++ **** ++
| **** |
| **** |
1.5 ++ **** ++
| **** |
+ **** + + + + + +
1 **---------+-----------+----------+----------+-----------+---------++
1 1.5 2 2.5 3 3.5 4
Servers
testdb=#
HTH
Ian Barwick
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