Horton

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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-12-13T10:05:05Z
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.

On Thu, Dec 12, 2019 at 9:45 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Wed, Dec 11, 2019 at 5:22 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Mon, Dec 9, 2019 at 1:27 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > >
> > > I have review the patch set and here are few comments/questions
> > >
> > > 1.
> > > +static void
> > > +pg_decode_stream_change(LogicalDecodingContext *ctx,
> > > + ReorderBufferTXN *txn,
> > > + Relation relation,
> > > + ReorderBufferChange *change)
> > > +{
> > > + OutputPluginPrepareWrite(ctx, true);
> > > + appendStringInfo(ctx->out, "streaming change for TXN %u", txn->xid);
> > > + OutputPluginWrite(ctx, true);
> > > +}
> > >
> > > Should we show the tuple in the streamed change like we do for the
> > > pg_decode_change?
> > >
> >
> > I think so.  The patch shows the message in
> > pg_decode_stream_message(), so why to prohibit showing tuple here?
> >
> > > 2. pg_logical_slot_get_changes_guts
> > > It recreate the decoding slot [ctx =
> > > CreateDecodingContext(InvalidXLogRecPtr] but doesn't set the streaming
> > > to false, should we pass a parameter to
> > > pg_logical_slot_get_changes_guts saying whether we want streamed results or not
> > >
> >
> > CreateDecodingContext internally calls StartupDecodingContext which
> > sets the value of streaming based on if the plugin has provided
> > callbacks for streaming functions. Isn't that sufficient?  Why do we
> > need additional parameters here?
>
> I don't think that if plugin provides streaming function then we
> should stream.  Like pgoutput plugin provides streaming function but
> we only stream if streaming is on in create subscription command.  So
> I feel that should be true with any plugin.
>

How about adding a new boolean parameter (streaming) in
pg_create_logical_replication_slot()?

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com