| From: | "Markus Bertheau" <mbertheau(dot)pg(at)googlemail(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "ITAGAKI Takahiro" <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Batch update of indexes on data loading |
| Date: | 2008-02-29 04:40:41 |
| Message-ID: | 684362e10802282040j4ac01d41j72465b940d8a6768@mail.gmail.com |
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| Lists: | pgsql-hackers |
2008/2/29, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> > BTW, why REINDEX requires access exclusive lock? Read-only queries
> > are forbidden during the operation now, but I feel they are ok
> > because REINDEX only reads existing tuples. Can we do REINDEX
> > holding only shared lock on the index?
>
> No. When you commit the reindex, the old copy of the index will
> instantaneously disappear; it will not do for someone to be actively
> scanning that copy.
Can a shared lock be taken at first, and when the new index is ready,
in order to delete the old index, elevate that lock to an exclusive
one?
Markus
--
Markus Bertheau
Blog: http://www.bluetwanger.de/blog/
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