Home > mailing lists

Thread: psql seems to hang during delete query

psql seems to hang during delete query

From

"surabhi.ahuja"

Date:

20 July 2006, 05:58:23

i am using postgresql 8.0.0

my disk is 100% full

i have a database called x

i do the following

psql x

delete from table;

nothing happens

i try to see the top output

i see the following

1768 sdc 25 0 41860 32m 30m R 99.7 0.8 11:29.35 postmaster
i also saw this appearing

2525 root 16 0 7296 720 620 S 0.3 0.0 0:07.62 hald-addon-stor

its been almost half an hour

and the database is still in the same state. (all the rows still exist)

what is happening?

hasnt it started deleteing yet?

postgreslog dont say anything.

what can be done in such a case?

thanks,

regards

Surabhi

unsubscribe

From

Timothy Smith

Date:

20 July 2006, 06:25:41

Re: psql seems to hang during delete query

From

"Harald Armin Massa"

Date:

20 July 2006, 06:46:09

You can't delete from a full disk :)

No, really: database systems need space for logging, WAL, whatever.

And even with "delete" PostgreSQL will free no single byte, as deleting is done with marking the row as deleted. Read up on multi version concurrency why this has to be that way.

To reclaim space: vacuum freeze

So, to get space, you have to have space first. Delete something else.

Harald

On 7/20/06, surabhi.ahuja <surabhi.ahuja@iiitb.ac.in> wrote:

i am using postgresql 8.0.0

my disk is 100% full

i have a database called x

i do the following
psql x
delete from table;

nothing happens

i try to see the top output

i see the following
1768 sdc 25 0 41860 32m 30m R 99.7 0.8 11:29.35 postmaster
i also saw this appearing

2525 root 16 0 7296 720 620 S 0.3 0.0 0:07.62 hald-addon-stor

its been almost half an hour
and the database is still in the same state. (all the rows still exist)

what is happening?
hasnt it started deleteing yet?
postgreslog dont say anything.

what can be done in such a case?
thanks,
regards
Surabhi

--
GHUM Harald Massa
persuadere et programmare
Harald Armin Massa
Reinsburgstraße 202b
70197 Stuttgart
0173/9409607
-
on different matter:
EuroPython 2006 is over. It was a GREAT conference. If you missed it, now you can prepare budget for visiting EuroPython 2007.

Re: psql seems to hang during delete query

From

"surabhi.ahuja"

Date:

20 July 2006, 07:12:55

so how much space should be free so that i am able to delete

i have a hard disk of size 130 G.

thanks,

regards

Surabhi

From: Harald Armin Massa [mailto:haraldarminmassa@gmail.com]
Sent: Thu 7/20/2006 12:16 PM
To: surabhi.ahuja
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] psql seems to hang during delete query

***********************
Your mail has been scanned by InterScan VirusWall.
***********-***********

On 7/20/06, surabhi.ahuja <surabhi.ahuja@iiitb.ac.in> wrote:

i am using postgresql 8.0.0

my disk is 100% full

i have a database called x

i do the following
psql x
delete from table;

nothing happens

i try to see the top output

i see the following
1768 sdc 25 0 41860 32m 30m R 99.7 0.8 11:29.35 postmaster
i also saw this appearing

2525 root 16 0 7296 720 620 S 0.3 0.0 0:07.62 hald-addon-stor

its been almost half an hour
and the database is still in the same state. (all the rows still exist)

what is happening?
hasnt it started deleteing yet?
postgreslog dont say anything.

what can be done in such a case?
thanks,
regards
Surabhi

Re: psql seems to hang during delete query

From

Sven Willenberger

Date:

20 July 2006, 19:55:46

On Thu, 2006-07-20 at 12:48 +0530, surabhi.ahuja wrote:
> so how much space should be free so that i am able to delete
>
> i have a hard disk of size 130 G.
>
>
> thanks,
> regards
> Surabhi
>
>
> ______________________________________________________________________
If you are trying to delete the entire contents of a table (and are not
using slony replication or similar) then a simple TRUNCATE <tablename>
will achieve the desired result and free up some diskspace.
Alternatively, if you have indexes on the table, you could try to drop
the indexes (if they are bloated, you can probably regain some diskspace
that way). Delete the rows you need and then create the indexes anew.

Sven