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Re: Batch update of indexes on data loading

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 (view raw or flat)
Thread:
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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