From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Cc: Andres Freund <andres@anarazel.de>
Cc: Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Ideriha, Takeshi <ideriha.takeshi@jp.fujitsu.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Cc: Michael Paquier <michael.paquier@gmail.com>
Cc: David Steele <david@pgmasters.net>
Cc: Craig Ringer <craig@2ndquadrant.com>
Subject: Re: Protect syscache from bloating with negative cache entries
Date: Wed, 06 Mar 2019 15:17:11 -0500
Message-ID: <1752.1551903431@sss.pgh.pa.us> (raw)
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References: <CA+TgmoZXw+SwK_9Tp=wLqZDstW_X+Ant=rd7K+q4zmYONPuL=w@mail.gmail.com>
<20190225.152653.211323929.horiguchi.kyotaro@lab.ntt.co.jp>
<CA+Tgmoa2b-LUF9h3wugD9ZA5MP0xyu2kJYHC9L6sdLywNSmhBQ@mail.gmail.com>
<20190301.173245.25820912.horiguchi.kyotaro@lab.ntt.co.jp>
<CA+TgmobXDWanVtVjLpayQnWfyTd49ma4j1q71ek_Ce=Z9A2UBg@mail.gmail.com>
Robert Haas <robertmhaas@gmail.com> writes:
> OK, so this is getting simpler, but I'm wondering why we need
> dlist_move_tail() at all. It is a well-known fact that maintaining
> LRU ordering is expensive and it seems to be unnecessary for our
> purposes here.
Yeah ... LRU maintenance was another thing that used to be in the
catcache logic and was thrown out as far too expensive. Your idea
of just using a clock sweep instead seems plausible.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, horiguchi.kyotaro@lab.ntt.co.jp, andres@anarazel.de, tsunakawa.takay@jp.fujitsu.com, alvherre@2ndquadrant.com, tomas.vondra@2ndquadrant.com, bruce@momjian.us, ideriha.takeshi@jp.fujitsu.com, pgsql-hackers@lists.postgresql.org, michael.paquier@gmail.com, david@pgmasters.net, craig@2ndquadrant.com
Subject: Re: Protect syscache from bloating with negative cache entries
In-Reply-To: <1752.1551903431@sss.pgh.pa.us>
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