Horton

RE: [Patch] Optimize dropping of relation buffers using dlist

tsunakawa.takay@fujitsu.com <tsunakawa.takay@fujitsu.com>

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From: "tsunakawa.takay@fujitsu.com" <tsunakawa.takay@fujitsu.com>
To: 'Amit Kapila' <amit.kapila16@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: "k.jamison@fujitsu.com" <k.jamison@fujitsu.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2020-09-23T02:34:45Z
Lists: pgsql-hackers 
From: Amit Kapila <amit.kapila16@gmail.com>
> > > > Don't
> > > > we need to guarantee the cache to be valid while recovery?
> > > >
> > >
> > > One possibility could be that we somehow detect that the value we
> > > are using is cached one and if so then only do this optimization.
> >
> > I basically like this direction.  But I'm not sure the additional
> > parameter for smgrnblocks is acceptable.
> >
> > But on the contrary, it might be a better design that
> > DropRelFileNodeBuffers gives up the optimization when
> > smgrnblocks(,,must_accurate = true) returns InvalidBlockNumber.
> >
> 
> I haven't thought about what is the best way to achieve this. Let us see if
> Tsunakawa-San or Kirk-San has other ideas on this?

I see no need for smgrnblocks() to add an argument as it returns the correct cached or measured value.



Regards
Takayuki Tsunakawa

Commits

  1. Fix size overflow in calculation introduced by commits d6ad34f3 and bea449c6.

  2. Optimize DropRelFileNodesAllBuffers() for recovery.

  3. Optimize DropRelFileNodeBuffers() for recovery.

  4. Cache smgrnblocks() results in recovery.

  5. Add a check to prevent overwriting valid data if smgrnblocks() gives a