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: 2020-02-10T08:22:13Z
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 Fri, Feb 7, 2020 at 4:18 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Wed, Feb 5, 2020 at 4:05 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Wed, Feb 5, 2020 at 9:46 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > >
> > > Fixed in the latest version sent upthread.
> > >
> >
> > Okay, thanks.  I haven't looked at the latest version of patch series
> > as I was reviewing the previous version and I think all of these
> > comments are in the patch which is not modified.  Here are my
> > comments:
> >
> > I think we don't need to maintain
> > v8-0007-Support-logical_decoding_work_mem-set-from-create as per
> > discussion in one of the above emails [1] as its usage is not clear.
> >
> > v8-0008-Add-support-for-streaming-to-built-in-replication
> > 1.
> > -      information.  The allowed options are <literal>slot_name</literal> and
> > -      <literal>synchronous_commit</literal>
> > +      information.  The allowed options are <literal>slot_name</literal>,
> > +      <literal>synchronous_commit</literal>, <literal>work_mem</literal>
> > +      and <literal>streaming</literal>.
> >
> > As per the discussion above [1], I don't think we need work_mem here.
> > You might want to remove the other usage from the patch as well.
>
> After putting more thought on this it appears that there could be some
> use cases for setting the work_mem from the subscription,  Assume a
> case where data are coming from two different origins and based on the
> origin ids different slots might collect different type of changes,
> So isn't it good to have different work_mem for different slots?  I am
> not saying that the current way of implementing is the best one but
> that we can improve.  First, we need to decide whether we have a use
> case for this or not.
>

That is the whole point.  I don't see a very clear usage of this and
neither did anybody explained clearly how it will be useful.  I am not
denying that what you are describing has no use, but as you said we
might need to invent an entirely new way even if we have such a use.
I think it is better to avoid the requirements which are not essential
for this patch.

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