Horton

Re: Patch: Write Amplification Reduction Method (WARM)

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Bruce Momjian <bruce@momjian.us>, Jaime Casanova <jaime.casanova@2ndquadrant.com>, Haribabu Kommi <kommi.haribabu@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-03-20T16:12:02Z
Lists: pgsql-hackers 
Pavan Deolasee wrote:
> On Tue, Mar 14, 2017 at 7:17 AM, Alvaro Herrera <alvherre@2ndquadrant.com>
> wrote:

> > I didn't like this comment very much.  But it's not necessary: you have
> > already given relcache responsibility for setting rd_supportswarm.  The
> > only problem seems to be that you set it in RelationGetIndexAttrBitmap
> > instead of RelationGetIndexList, but it's not clear to me why.  I think
> > if the latter function is in charge, then we can trust the flag more
> > than the current situation.
> 
> I looked at this today.  AFAICS we don't have access to rd_amroutine in
> RelationGetIndexList since we don't actually call index_open() in that
> function. Would it be safe to do that? I'll give it a shot, but thought of
> asking here first.

Ah, you're right, we only have the pg_index tuple for the index, not the
pg_am one.  I think one pg_am cache lookup isn't really all that
terrible (though we should ensure that there's no circularity problem in
doing that), but I doubt that going to the trouble of invoking the
amhandler just to figure out if it supports WARM is acceptable.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Implement SortSupport for macaddr data type

  2. Simplify check of modified attributes in heap_update

  3. Remove direct uses of ItemPointer.{ip_blkid,ip_posid}

  4. Fix CatalogTupleInsert/Update abstraction for case of shared indstate.

  5. Provide CatalogTupleDelete() as a wrapper around simple_heap_delete().

  6. Band-aid fix for incorrect use of view options as StdRdOptions.

  7. Update visibility map in the second phase of vacuum.

  8. Avoid having two copies of the HOT-chain search logic.

  9. Postgres95 1.01 Distribution - Virgin Sources