Horton

Re: Patch: Write Amplification Reduction Method (WARM)

Pavan Deolasee <pavan.deolasee@gmail.com>

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From: Pavan Deolasee <pavan.deolasee@gmail.com>
To: Alvaro Herrera <alvherre@2ndquadrant.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: 2017-03-20T15:03:23Z
Lists: pgsql-hackers 
On Wed, Mar 15, 2017 at 12:46 AM, Alvaro Herrera <alvherre@2ndquadrant.com>
wrote:

> Pavan Deolasee wrote:
> > On Tue, Mar 14, 2017 at 7:17 AM, Alvaro Herrera <
> alvherre@2ndquadrant.com>
> > wrote:
>
> > > I have already commented about the executor involvement in btrecheck();
> > > that doesn't seem good.  I previously suggested to pass the EState down
> > > from caller, but that's not a great idea either since you still need to
> > > do the actual FormIndexDatum.  I now think that a workable option would
> > > be to compute the values/isnulls arrays so that btrecheck gets them
> > > already computed.
> >
> > I agree with your complaint about modularity violation. What I am unclear
> > is how passing values/isnulls array will fix that. The way code is
> > structured currently, recheck routines are called by index_fetch_heap().
> So
> > if we try to compute values/isnulls in that function, we'll still need
> > access EState, which AFAIU will lead to similar violation. Or am I
> > mis-reading your idea?
>
> You're right, it's still a problem.



BTW I realised that we don't really need those executor bits in recheck
routines. We don't support WARM when attributes in index expressions are
modified. So we really don't need to do any comparison for those
attributes. I've written a separate form of FormIndexDatum() which will
only return basic index attributes and comparing them should be enough.
Will share rebased and updated patch soon.

Thanks,
Pavan

-- 
 Pavan Deolasee                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, 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