Re: Tid scan increments value of pg_stat_all_tables.seq_scan. (but not seq_tup_read)

From: Kasahara Tatsuhito <kasahara(dot)tatsuhito(at)gmail(dot)com>
To: Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
Cc: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Tid scan increments value of pg_stat_all_tables.seq_scan. (but not seq_tup_read)
Date: 2020-02-03 09:20:49
Message-ID: CAP0=ZV+Ki3Mp1Egr6jOQOSrJzZ5PysPgB16wwqS4vRXH8--i7g@mail.gmail.com
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On Mon, Feb 3, 2020 at 5:33 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
> Thanks for explaining that! But heap_beginscan_internal() was really
> called in TidScan case?
Oh, you are right.
Tid Scan started calling table_beginscan from v12 (commit 147e3722f7).
So previously(-v11), Tid Scan might never calls heap_beginscan_internal().

Therefore, from v12, Tid scan not only increases the value of
seq_scan, but also acquires a predicate lock.

Best regards,
--
Tatsuhito Kasahara
kasahara.tatsuhito _at_ gmail.com

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