Horton

Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: amit.kapila16@gmail.com
Cc: robertmhaas@gmail.com, dilipbalaut@gmail.com, michael@paquier.xyz, tomas.vondra@2ndquadrant.com, peter.eisentraut@2ndquadrant.com, pgsql-hackers@postgresql.org
Date: 2019-12-20T08:29:21Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Tighten the concurrent abort check during decoding.

  2. Improve hash_create()'s API for some added robustness.

  3. Use HASH_BLOBS for xidhash.

  4. Fix initialization of RelationSyncEntry for streaming transactions.

  5. Remove unused function declaration in logicalproto.h.

  6. Add additional tests to test streaming of in-progress transactions.

  7. Fix inline marking introduced in commit 464824323e.

  8. Add support for streaming to built-in logical replication.

  9. Fix the SharedFileSetUnregister API.

  10. Fix comment in procarray.c

  11. Suppress compiler warning in non-cassert builds.

  12. Extend the BufFile interface.

  13. Mark a few logical decoding related variables with PGDLLIMPORT.

  14. Implement streaming mode in ReorderBuffer.

  15. Extend the logical decoding output plugin API with stream methods.

  16. WAL Log invalidations at command end with wal_level=logical.

  17. Immediately WAL-log subtransaction and top-level XID association.

  18. Allow logical replication to transfer data in binary format.

  19. Only superuser can set sslcert/sslkey in postgres_fdw user mappings

  20. Track statistics for spilling of changes from ReorderBuffer.

  21. Add logical_decoding_work_mem to limit ReorderBuffer memory usage.

  22. logical decoding: process ASSIGNMENT during snapshot build

  23. Emit invalidations to standby for transactions without xid.

Hello.

At Fri, 13 Dec 2019 14:46:20 +0530, Amit Kapila <amit.kapila16@gmail.com> wrote in 
> On Wed, Dec 11, 2019 at 11:46 PM Robert Haas <robertmhaas@gmail.com> wrote:
> >
> > On Mon, Dec 2, 2019 at 3:32 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > > I have rebased the patch set on the latest head.
> >
> > 0001 looks like a clever approach, but are you sure it doesn't hurt
> > performance when many small XLOG records are being inserted? I think
> > XLogRecordAssemble() can get pretty hot in some workloads.
> >
> > With regard to 0002, logging a separate WAL record for each
> > invalidation seems painful; I think most operations that generate
> > invalidations generate a bunch of them all at once. Perhaps you could
> > just queue up invalidations as they happen, and then force anything
> > that's been queued up to be emitted into WAL just before you emit any
> > WAL record that might need to be decoded.
> >
> 
> I feel we can log the invalidations of the entire command at one go if
> we log at CommandEndInvalidationMessages.  We already have all the
> invalidations of current command in
> transInvalInfo->CurrentCmdInvalidMsgs.  This can save us the effort of
> maintaining a new separate list/queue for invalidations and to a good
> extent, it will ameliorate your concern of logging each invalidation
> separately.

I have a question on this. Does that mean that the current logical
decoder (or reorderbuffer) may emit incorrect result if it made a
catalog change during the current transaction being decoded? If so,
this is not a feature but a bug fix.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center