Horton

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

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2018-01-31T06:53:06Z
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 20, 2018 at 7:08 AM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> On 01/19/2018 03:34 PM, Tomas Vondra wrote:
>> Attached is v5, fixing a silly bug in part 0006, causing segfault when
>> creating a subscription.
>>
>
> Meh, there was a bug in the sgml docs (<variable> vs. <varname>),
> causing another failure. Hopefully v6 will pass the CI build, it does
> pass a build with the same parameters on my system.

Thank you for working on this. This patch would be helpful for
synchronous replication.

I haven't looked at the code deeply yet, but I've reviewed the v6
patch set especially on subscriber side. All of the patches can be
applied to current HEAD cleanly. Here is review comment.

----
CREATE SUBSCRIPTION commands accept work_mem < 64 but it leads ERROR
on publisher side when starting replication. Probably we should check
the value on the subscriber side as well.

----
When streaming = on, if we drop subscription in the middle of
receiving stream changes, DROP SUBSCRIPTION could leak tmp files
(.chages file and .subxacts file). Also it also happens when a
transaction on upstream aborted without abort record.

----
Since we can change both streaming option and work_mem option by ALTER
SUBSCRIPTION, documentation of ALTER SUBSCRIPTION needs to be updated.

----
If we create a subscription without any options, both
pg_subscription.substream and pg_subscription.subworkmem are set to
null. However, since GetSubscription are't aware of NULL we start the
replication with invalid options like follows.
LOG:  received replication command: START_REPLICATION SLOT "hoge_sub"
LOGICAL 0/0 (proto_version '2', work_mem '893219954', streaming 'on',
publication_names '"hoge_pub"')

I think we can set substream to false and subworkmem to -1 instead of
null, and then makes libpqrcv_startstreaming not set streaming option
if stream is -1.

----
Some WARNING messages appeared. Maybe these are for debug purpose?

WARNING:  updating stream stats 0x1c12ef8 4 3 65604
WARNING: UpdateSpillStats: updating stats 0x1c12ef8 0 0 0 39 41 2632080

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center