Re: Patch to improve performance of replay of AccessExclusiveLock

From: Andres Freund <andres(at)anarazel(dot)de>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch to improve performance of replay of AccessExclusiveLock
Date: 2017-03-07 17:04:12
Message-ID: 20170307170412.p5otd6fhpsph6jcc@alap3.anarazel.de
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Hi,

On 2017-03-08 00:15:05 +1300, David Rowley wrote:
> -static List *RecoveryLockList;
> +/*
> + * RecoveryLockTable is a poor man's hash table that allows us to partition
> + * the stored locks. Which partition a lock is stored in is determined by the
> + * xid which the lock belongs to. The hash function is very simplistic and
> + * merely performs a binary AND against the final 0-based partition number.
> + * Splitting into partitions in this way avoids having to look through all
> + * locks to find one specific to a given xid.
> + */
> +static List **RecoveryLockTable;

Why are we open coding this? That strikes me as a bad plan...

Regards,

Andres

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