Horton

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

Dilip Kumar <dilipbalaut@gmail.com>

View thread
From: Dilip Kumar <dilipbalaut@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Erik Rijkers <er@xs4all.nl>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-06-30T04:43:17Z
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 Tue, Jun 30, 2020 at 9:20 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Mon, Jun 29, 2020 at 4:24 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > On Mon, Jun 22, 2020 at 4:30 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> > >
> > > Other than above tests, can we somehow verify that the invalidations
> > > generated at commit time are the same as what we do with this patch?
> > > We have verified with individual commands but it would be great if we
> > > can verify for the regression tests.
> >
> > I have verified this using a few random test cases.  For verifying
> > this I have made some temporary code changes with an assert as shown
> > below.  Basically, on DecodeCommit we call
> > ReorderBufferAddInvalidations function only for an assert checking.
> >
> > -void
> >  ReorderBufferAddInvalidations(ReorderBuffer *rb, TransactionId xid,
> >                                                           XLogRecPtr
> > lsn, Size nmsgs,
> > -
> > SharedInvalidationMessage *msgs)
> > +
> > SharedInvalidationMessage *msgs, bool commit)
> >  {
> >         ReorderBufferTXN *txn;
> >
> >         txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
> > -
> > +       if (commit)
> > +       {
> > +               Assert(txn->ninvalidations == nmsgs);
> > +               return;
> > +       }
> >
> > The result is that for a normal local test it works fine.  But with
> > regression suit, it hit an assert at many places because if the
> > rollback of the subtransaction is involved then at commit time
> > invalidation messages those are not logged whereas with command time
> > invalidation those are logged.
> >
>
> Yeah, somehow, we need to ignore rollback to savepoint tests and
> verify for others.

Yeah, I have run the regression suite,  I can see a lot of failure
maybe we can somehow see the diff and confirm that all the failures
are due to rollback to savepoint only.  I will work on this.

>
> > As of now, I have only put assert on the count,  if we need to verify
> > the exact messages then we might need to somehow categories the
> > invalidation messages because the ordering of the messages will not be
> > the same.  For testing this we will have to arrange them by category
> > i.e relcahce, catcache and then we can compare them.
> >
>
> Can't we do this by verifying that each message at commit time exists
> in the list of invalidation messages we have collected via processing
> XLOG_XACT_INVALIDATIONS?

Let me try what is the easiest way to test this.

>
> One additional question on patch
> v30-0003-Extend-the-output-plugin-API-with-stream-methods:
> +static void
> +stream_commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
> + XLogRecPtr apply_lsn)
> {
> ..
> ..
> + state.report_location = apply_lsn;
> ..
> ..
> + ctx->write_location = apply_lsn;
> ..
> }
>
> Can't we name the last parameter as 'commit_lsn' as that is how
> documentation in the patch spells it and it sounds more appropriate?

You are right commit_lsn seems more appropriate here.

> Also, is there a reason for assigning report_location and
> write_location differently than what we do in commit_cb_wrapper?
> Basically, assign those as txn->final_lsn and txn->end_lsn
> respectively.

Yes, I think it should be handled in same way as commit_cb_wrapper.
Because before calling ReorderBufferStreamCommit in
ReorderBufferCommit, we are properly updating the final_lsn as well as
the end_lsn.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com