Tom Lane schrieb:
Martijn van Oosterhout <kleptog@xxxxxxxxx> writes:
... Your real problem is that
you're using the information_schema which has to do all sorts of extra
work for standards compliance. If you don't need that you're going to
be much better off just using the system catalogs.
To put that in some perspective:
regression=> create table fooey(f1 int);
CREATE TABLE
regression=> \timing
Timing is on.
regression=> select column_name from information_schema.columns where table_nam
e = 'fooey';
column_name
-------------
f1
(1 row)
Time: 84.388 ms
regression=> select attname from pg_attribute where attrelid = 'fooey'::regclas
s and attnum > 0 and not attisdropped;
attname
---------
f1
(1 row)
Time: 7.834 ms
regression=>
When you look at the plans involved (information_schema.columns is an
8-way join) the surprising thing is not that the first query is so slow,
it's that it's so fast.
AAAH! That is the reason.
So creating a temporary table from the information schema would speedup
the whole thing by factor 10 (at least), I guess.
Thanks a lot!
;)
Greetings,
Alexander Elgert
