Re: Alter table command is pretty slow

sreenivas(at)gmail(dot)com (Sreenivas K) writes:
> I have installed the PostgreSQL native Windows (8.0 using the Windows
> MSI installer) on a Windows 2K box. I accepted all of the
> installation defaults. It is running successfully and my application
> that stores data via Hibernate 2.0 is working. But it is taking too
> long [>15 mimutes] if I try to execute any DDL commands . I Issued
> vacuum command just before running a DDL. My computer has 512 MB of
> RAM. Why is it so slow?
>
> Any help would be great.

You might want to look at pg_stat_activity (assuming activity logging
is turned on) as well as pg_locks.

DDL commands require exclusive locks on the tables that they are
modifying, and *anything* else that may be touching the tables will
block the DDL commands.

VACUUM will definitely block DDL...

At any rate, pg_stat_activity can tell you what queries are busy in
the system. And pg_locks will tell you what relations are in what
states. (You'll need to join pg_locks against pg_class in order to
get relation names.)
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