Horton

Re: HASH_BLOBS hazards (was Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions)

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, 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>
Date: 2020-12-15T08:20:30Z
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 Mon, Dec 14, 2020 at 01:59:03PM -0500, Tom Lane wrote:
> * Should we just have a blanket insistence that all callers supply
> HASH_ELEM?  The default sizes that dynahash.c uses without that are
> undocumented and basically useless.

+1

> we should just rip out all those memsets as pointless, since there's
> basically no case where you'd use the memset to fill a field that
> you meant to pass as zero.  The fact that hash_create() doesn't
> read fields it's not told to by a flag means we should not need
> the memsets to avoid uninitialized-memory reads.

On Mon, Dec 14, 2020 at 06:55:20PM -0500, Tom Lane wrote:
> Here's a rolled-up patch that does some further documentation work
> and gets rid of the unnecessary memset's as well.

+1 on removing the memset() calls.  That said, it's not a big deal if more
creep in over time; it doesn't qualify as a project policy violation.

> @@ -329,6 +328,11 @@ InitShmemIndex(void)
>   * whose maximum size is certain, this should be equal to max_size; that
>   * ensures that no run-time out-of-shared-memory failures can occur.
>   *
> + * *infoP and hash_flags should specify at least the entry sizes and key

s/should/must/