Horton

Re: Setting pd_lower in GIN metapage

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Michael Paquier <michael.paquier@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-09-13T04:05:19Z
Lists: pgsql-hackers 
Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> writes:
> On 2017/09/12 23:27, Amit Kapila wrote:
>> I think one point which might be missed is that the patch needs to
>> modify pd_lower for all usages of metapage, not only when it is first
>> time initialized.

> Maybe I'm missing something, but isn't the metadata size fixed and hence
> pd_lower won't change once it's initialized?  Maybe, it's not true for all
> index types?

No, the point is that you might be dealing with an index recently
pg_upgraded from v10 or before, which does not have the correct
value for pd_lower on that page.  This has to be coped with.

			regards, tom lane

Commits

  1. Flag index metapages as standard-format in xlog.c calls.

  2. Set the metapage's pd_lower correctly in brin, gin, and spgist indexes.