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>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Erik Rijkers <er@xs4all.nl>, Jeff Janes <jeff.janes@gmail.com>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Noah Misch <noah@leadboat.com>
Date: 2021-04-28T05:30:01Z
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.

Tom Lane has raised a complaint on pgsql-commiters [1] about one of
the commits related to this work [2]. The new member wrasse is showing
Warning:

"/export/home/nm/farm/studio64v12_6/HEAD/pgsql.build/../pgsql/src/backend/replication/logical/reorderbuffer.c",
line 2510: Warning: Likely null pointer dereference (*(curtxn+272)):
ReorderBufferProcessTXN

The Warning is for line:
curtxn->concurrent_abort = true;

Now, we can simply fix this warning by adding an if check like:
if (curtxn)
curtxn->concurrent_abort = true;

However, on further discussion, it seems that is not sufficient here
because the callbacks can throw the surrounding error code
(ERRCODE_TRANSACTION_ROLLBACK) where we set concurrent_abort flag for
a completely different scenario. I think here we need a
stronger check to ensure that we set concurrent abort flag and do
other things in that check only when we are decoding non-committed
xacts. The idea I have is to additionally check that we are decoding
streaming or prepared transaction (the same check as we have for
setting curtxn) or we can check if CheckXidAlive is a valid
transaction id. What do you think?

[1] - https://www.postgresql.org/message-id/2752962.1619568098%40sss.pgh.pa.us
[2] - https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=7259736a6e5b7c7588fff9578370736a6648acbb

-- 
With Regards,
Amit Kapila.