Horton

Re: Patch: Write Amplification Reduction Method (WARM)

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Stephen Frost <sfrost@snowman.net>, Andres Freund <andres@anarazel.de>, Pavan Deolasee <pavan.deolasee@gmail.com>, 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: 2017-02-01T00:36:53Z
Lists: pgsql-hackers 
Tom Lane wrote:

> BTW, the reason I think it's good cleanup is that it's something that my
> colleagues at Salesforce also had to do as part of putting PG on top of a
> different storage engine that had different ideas about index handling.
> Essentially it's providing a bit of abstraction as to whether catalog
> storage is exactly heaps or not (a topic I've noticed Robert is starting
> to take some interest in, as well).

Yeah, I remembered that too.  Of course, we'd need to change the whole
idea of mapping tuples to C structs too, but this seemed a nice step
forward.  (I renamed Pavan's proposed routine precisely to avoid the
word "Heap" in it.)

> However, the patch misses an
> important part of such an abstraction layer by not also converting
> catalog-related simple_heap_delete() calls into some sort of
> CatalogTupleDelete() operation.  It is certainly a peculiarity of
> PG heaps that deletions don't require any immediate index work --- most
> other storage engines would need that.

> I propose that we should finish the job by inventing CatalogTupleDelete(),
> which for the moment would be a trivial wrapper around
> simple_heap_delete(), maybe just a macro for it.
> 
> If there's no objections I'll go make that happen in a day or two.

Sounds good.

-- 
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