Horton

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

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-01-04T06:24:19Z
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 Sat, Jan 4, 2020 at 10:00 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Sun, Dec 29, 2019 at 1:34 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > On Sat, Dec 28, 2019 at 9:33 PM Tomas Vondra
> > <tomas.vondra@2ndquadrant.com> wrote:
> > +static void
> > +set_schema_sent_in_streamed_txn(RelationSyncEntry *entry, TransactionId xid)
> > +{
> > + MemoryContext oldctx;
> > +
> > + oldctx = MemoryContextSwitchTo(CacheMemoryContext);
> > +
> > + entry->streamed_txns = lappend_int(entry->streamed_txns, xid);
> > +
> > + MemoryContextSwitchTo(oldctx);
> > +}
> > I was looking into the schema tracking solution and I have one
> > question, Shouldn't we remove the topxid from the list if the
> > (sub)transaction is aborted?  because once it is aborted we need to
> > resent the schema.
> >
>
> I think you are right because, at abort, the subscriber would remove
> the changes (for a subtransaction) including the schema changes sent
> and then it won't be able to understand the subsequent changes sent by
> the publisher.  Won't we need to remove xid from the list at commit
> time as well, otherwise, the list will keep on growing.
Yes, we need to remove the xid from the list at the time of commit as well.

 One more
> thing, we need to search the list of all the relations in the local
> map to find xid being aborted/committed, right?  If so, won't it be
> costly doing at each transaction abort/commit?
Yeah, if multiple concurrent transactions operate on the common
relations then the list can grow longer.  I am not sure how many
concurrent large transactions are possible maybe it won't be huge that
searching will be very costly.  Otherwise, we can maintain the sorted
array of the xids and do a binary search or we can maintain hash?

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