Horton

Re: Write Ahead Logging for Hash Indexes

Jeff Janes <jeff.janes@gmail.com>

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From: Jeff Janes <jeff.janes@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Jesper Pedersen <jesper.pedersen@redhat.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-11-08T17:26:41Z
Lists: pgsql-hackers 
On Sat, Sep 24, 2016 at 10:00 PM, Amit Kapila <amit.kapila16@gmail.com>
wrote:

> On Fri, Sep 23, 2016 at 5:34 PM, Amit Kapila <amit.kapila16@gmail.com>
> wrote:
> >
> > I think here I am slightly wrong.  For the full page writes, it do use
> > RBM_ZERO_AND_LOCK mode to read the page and for such mode we are not
> > doing page verification check and rather blindly setting the page to
> > zero and then overwrites it with full page image.  So after my fix,
> > you will not see the error of checksum failure.  I have a fix ready,
> > but still doing some more verification.  If everything passes, I will
> > share the patch in a day or so.
> >
>
> Attached patch fixes the problem, now we do perform full page writes
> for bitmap pages.  Apart from that, I have rebased the patch based on
> latest concurrent index patch [1].  I have updated the README as well
> to reflect the WAL logging related information for different
> operations.
>
> With attached patch, all the review comments or issues found till now
> are addressed.
>

This needs to be updated to apply over concurrent_hash_index_v10.patch.

Unless we want to wait until that work is committed before doing more
review and testing on this.

Thanks,

Jeff

Commits

  1. Add a regression test for snapshot too old with hash indexes.

  2. hash: Add write-ahead logging support.

  3. Improve coding in _hash_addovflpage.

  4. Remove _hash_wrtbuf() in favor of calling MarkBufferDirty().

  5. Improve hash index bucket split behavior.