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: Jaime Casanova <jaime.casanova@2ndquadrant.com>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-03T17:45:47Z
Lists: pgsql-hackers

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On Tue, Jan 3, 2017 at 9:43 AM, Pavan Deolasee <pavan.deolasee@gmail.com>
wrote:

> The patch still disables WARM on system tables, something I would like to
> fix. But I've been delaying that because it will require changes at several
> places since indexes on system tables are managed separately.
>

Here is another version which fixes a bug that I discovered while adding
support for system tables. The patch set now also includes a patch to
enable WARM on system tables. I'm attaching that as a separate patch
because while the changes to support WARM on system tables are many, almost
all of them are purely mechanical. We need to pass additional information
to CatalogUpdateIndexes()/CatalogIndexInsert(). We need to tell these
routines whether the update leading to them was a WARM update and which
columns were modified so that it can correctly avoid adding new index
tuples for indexes for which index keys haven't changed.

I wish I could find another way of passing this information instead of
making changes at so many places, but the only other way I could think of
was tracking that information as part of the HeapTuple itself, which
doesn't seem nice and may also require changes at many call sites where
tuples are constructed. One minor improvement could be that instead of two,
we could just pass "modified_attrs" and a NULL value may imply non-WARM
update. Other suggestions are welcome though.

I'm quite happy that all tests pass even after adding support for system
tables. One reason for testing support for system tables was to ensure some
more code paths get exercised. As before, I've included Alvaro's
refactoring patch too.

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