Обсуждение: Drop big index
Hi, I need to drop some b-tree indexes because they are not used anymore. Size of indexes vary between 700 MB and 7 GB. I tried common DROP INDEX... but this query performed so long and blocked table so I had to interrupt it. Is there any way how to drop large indexes in non-blocking or /faster/ way? Regards, Vojta R.
Vojtech Rylko wrote: > I need to drop some b-tree indexes because they are not used anymore. > Size of indexes vary between 700 MB and 7 GB. I tried common DROP > INDEX... but this query performed so long and blocked table so I had to > interrupt it. Is there any way how to drop large indexes in non-blocking > or /faster/ way? Unfortunately not (yet). PostgreSQL 9.2 will have DROP INDEX CONCURRENTLY. Yours, Laurenz Albe
2012/2/15 Vojtěch Rylko <vojta.rylko@seznam.cz>: > this query performed so long and blocked table so I had to interrupt it. Is > there any way how to drop large indexes in non-blocking or /faster/ way? Usually the problem is not with the size of the index -- but some other running transactions that hold a read lock on the table, and preventing the DROP INDEX from getting an exclusive lock. If the exclusive lock is granted, the drop index is usually very fast. Run 'select * from pg_stat_activity' and see if there are any "<IDLE> in transaction" connections. It's normal to have these for a second or few, but longer idle transactions usually indicate an application bug -- it started a transaction, but "forgot" to rollback or commit. These are problematic for this exact reason -- locks can't be released until the transaction finishes. Regards, Marti
Albe Laurenz <laurenz.albe@wien.gv.at> wrote: > Vojtech Rylko wrote: > > I need to drop some b-tree indexes because they are not used anymore. > > Size of indexes vary between 700 MB and 7 GB. I tried common DROP > > INDEX... but this query performed so long and blocked table so I had to > > interrupt it. Is there any way how to drop large indexes in non-blocking > > or /faster/ way? > > Unfortunately not (yet). > PostgreSQL 9.2 will have DROP INDEX CONCURRENTLY. Really? Great! I have a use-case for that: an partial index, daily re-created (the index based on the date and includes the last N days), and sometimes we have trouble with this. Andreas -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknown) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
Dne 16.2.2012 9:53, Marti Raudsepp napsal(a): > 2012/2/15 Vojtěch Rylko<vojta.rylko@seznam.cz>: >> this query performed so long and blocked table so I had to interrupt it. Is >> there any way how to drop large indexes in non-blocking or /faster/ way? > Usually the problem is not with the size of the index -- but some > other running transactions that hold a read lock on the table, and > preventing the DROP INDEX from getting an exclusive lock. If the > exclusive lock is granted, the drop index is usually very fast. > > Run 'select * from pg_stat_activity' and see if there are any "<IDLE> > in transaction" connections. It's normal to have these for a second or > few, but longer idle transactions usually indicate an application bug > -- it started a transaction, but "forgot" to rollback or commit. These > are problematic for this exact reason -- locks can't be released until > the transaction finishes. > > Regards, > Marti > Thanks! Caused by "IDLE in transaction". My nightmare solved. Droping 7 GB index in 2353 ms. Regards, Vojtěch R.