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

Tomas Vondra <tomas.vondra@2ndquadrant.com>

From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2018-01-03T20:13:29Z
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 01/03/2018 09:06 PM, Tomas Vondra wrote:
> Hi,
> 
> attached is v4 of the patch series, with a couple of changes:
> 
> 1) Fixes a bunch of bugs I discovered during stress testing.
> 
> I'm not going to go into details, but the main fixes are related to
> properly updating progress from the worker, and not streaming when
> creating the logical replication slot.
> 
> 2) Introduces columns into pg_stat_replication.
> 
> The new columns track various kinds of statistics (number of xacts,
> bytes, ...) about spill-to-disk/streaming. This will be useful when
> tuning the GUC memory limit.
> 
> 3) Two temporary bugfixes that make the patch series work.
> 

Forgot to mention that the v4 also extends the CREATE SUBSCRIPTION to
allow customizing the streaming and memory limit. So you can do

    CREATE SUBSCRIPTION ... WITH (streaming=on, work_mem=1024)

and this subscription will allow streaming, and the logica_work_mem (on
provider) will be set to 1MB.

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services