Re: blocking index creation

2017-10-11 10:46 GMT-03:00 Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>:

> Neto pr wrote:
> > When creating index on table of approximately 10GB of data, the DBMS
> hangs (I think),
> > because even after waiting 10 hours there was no return of the command.
> > It happened by creating Hash indexes and B + tree indexes.
> > However, for some columns, it was successfully (L_RETURNFLAG, L_PARTKEY).
>
> > If someone has a hint how to speed up index creation so that it
> completes successfully.
>
> Look if CREATE INDEX is running or waiting for a lock (check the
> "pg_locks" table, see if the backend consumes CPU time).
>
>
In this moment now, there is an index being created in the Lineitem table
(+ - 10 Gb), and apparently it is locked, since it started 7 hours ago.
I've looked at the pg_locks table and look at the result, it's with
"ShareLock" lock mode.
Is this blocking correct? or should it be another type?

Before creating the index, should I set the type of transaction lock? What?
-------------------------------------------------------------------------------------------
SELECT
L.mode, c.relname, locktype, l.GRANTED, l.transactionid,
virtualtransaction
FROM pg_locks l, pg_class c
where c.oid = l.relation

-------------- RESULT
--------------------------------------------------------------
AccessShareLock pg_class_tblspc_relfilenode_index relation TRUE (null) 3/71
AccessShareLock pg_class_relname_nsp_index relation TRUE (null) 3/71
AccessShareLock pg_class_oid_index relation TRUE (null) 3/71
AccessShareLock pg_class relation TRUE (null) 3/71
AccessShareLock pg_locks relation TRUE (null) 3/71
ShareLock lineitem relation TRUE (null) 21/3769

> Maybe there is a long-running transaction that blocks the
> ACCESS EXCLUSIVE lock required. It could also be a prepared
> transaction.
>
> Yours,
> Laurenz Albe
>

Best Regards
Neto