Horton

RE: [PATCH] Speedup truncates of relation forks

Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>

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From: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
To: 'Masahiko Sawada' <sawada.mshk@gmail.com>, "Jamison, Kirk" <k.jamison@jp.fujitsu.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2019-06-14T00:10:07Z
Lists: pgsql-hackers

Commits

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  1. Speedup truncations of relation forks.

  2. Remove unused smgrdounlinkfork() function.

  3. Accelerate end-of-transaction dropping of relations

From: Masahiko Sawada [mailto:sawada.mshk@gmail.com]
>     for (i = 0; i < NBuffers; i++)
>     {
> (snip)
>         buf_state = LockBufHdr(bufHdr);
> 
>         /* check with the lower bound and skip the loop */
>         if (bufHdr->tag.blockNum < minBlock)
>         {
>             UnlockBufHdr(bufHdr, buf_state);
>             continue;
>         }
> 
>         for (k = 0; k < nforks; k++)
>         {
>             if (RelFileNodeEquals(bufHdr->tag.rnode, rnode.node) &&
>                 bufHdr->tag.forkNum == forkNum[k] &&
>                 bufHdr->tag.blockNum >= firstDelBlock[k])
> 
> But since we acquire the buffer header lock after all and the number
> of the internal loops is small (at most 3 for now)  the benefit will
> not be big.

Yeah, so I think we can just compare the block number without locking the buffer header here.


Regards
Takayuki Tsunakawa