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: Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-05-18T12:27:28Z
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, May 18, 2020 at 4:10 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Sun, May 17, 2020 at 12:41 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >

Few comments on v20-0010-Bugfix-handling-of-incomplete-toast-tuple
1.
+ /*
+ * If this is a toast insert then set the corresponding bit.  Otherwise, if
+ * we have toast insert bit set and this is insert/update then clear the
+ * bit.
+ */
+ if (toast_insert)
+ toptxn->txn_flags |= RBTXN_HAS_TOAST_INSERT;
+ else if (rbtxn_has_toast_insert(txn) &&
+ ChangeIsInsertOrUpdate(change->action))
+ {

Here, it might better to add a comment on why we expect only
Insert/Update?  Also, it might be better that we add an assert for
other operations.

2.
@@ -1865,8 +1920,8 @@ ReorderBufferProcessTXN(ReorderBuffer *rb,
ReorderBufferTXN *txn,
  * disk.
  */
  dlist_delete(&change->node);
- ReorderBufferToastAppendChunk(rb, txn, relation,
-   change);
+ ReorderBufferToastAppendChunk(rb, txn, relation,
+   change);
  }

This seems to be a spurious change.

3.
+ /*
+ * If streaming is enable and we have serialized this transaction because
+ * it had incomplete tuple.  So if now we have got the complete tuple we
+ * can stream it.
+ */
+ if (ReorderBufferCanStream(rb) && can_stream && rbtxn_is_serialized(toptxn)
+ && !(rbtxn_has_toast_insert(txn)) && !(rbtxn_has_spec_insert(txn)))
+ {

This comment is just saying what you are doing in the if-check.  I
think you need to explain the rationale behind it. I don't like the
variable name 'can_stream' because it matches ReorderBufferCanStream
whereas it is for a different purpose, how about naming it as
'change_complete' or something like that.  The check has many
conditions, can we move it to a separate function to make the code
here look clean?

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