Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions
Amit Kapila <amit.kapila16@gmail.com>
Commits
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the thread's linked commits as JSON, with link sources.
API reference →
-
Tighten the concurrent abort check during decoding.
- 2ce353fc1902 14.0 landed
-
Improve hash_create()'s API for some added robustness.
- b3817f5f7746 14.0 landed
-
Use HASH_BLOBS for xidhash.
- a1b8aa1e4eec 14.0 landed
-
Fix initialization of RelationSyncEntry for streaming transactions.
- 69bd60672af6 14.0 landed
-
Remove unused function declaration in logicalproto.h.
- ddd5f6d2609b 14.0 landed
-
Add additional tests to test streaming of in-progress transactions.
- 58b5ae9d62bd 14.0 landed
-
Fix inline marking introduced in commit 464824323e.
- ac15b499f7f9 14.0 landed
-
Add support for streaming to built-in logical replication.
- 464824323e57 14.0 landed
-
Fix the SharedFileSetUnregister API.
- 4ab77697f67a 14.0 landed
-
Fix comment in procarray.c
- 77c7267c37f7 14.0 cited
-
Suppress compiler warning in non-cassert builds.
- e942af7b8261 14.0 cited
-
Extend the BufFile interface.
- 808e13b282ef 14.0 landed
-
Mark a few logical decoding related variables with PGDLLIMPORT.
- b48cac3b10a0 14.0 landed
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Implement streaming mode in ReorderBuffer.
- 7259736a6e5b 14.0 landed
-
Extend the logical decoding output plugin API with stream methods.
- 45fdc9738b36 14.0 landed
-
WAL Log invalidations at command end with wal_level=logical.
- c55040ccd017 14.0 landed
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Immediately WAL-log subtransaction and top-level XID association.
- 0bead9af484c 14.0 landed
-
Allow logical replication to transfer data in binary format.
- 9de77b545313 14.0 cited
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Only superuser can set sslcert/sslkey in postgres_fdw user mappings
- cebf9d6e6ee1 13.0 cited
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Track statistics for spilling of changes from ReorderBuffer.
- 9290ad198b15 13.0 landed
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Add logical_decoding_work_mem to limit ReorderBuffer memory usage.
- cec2edfa7859 13.0 landed
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logical decoding: process ASSIGNMENT during snapshot build
- bac2fae05c77 13.0 cited
-
Emit invalidations to standby for transactions without xid.
- c6ff84b06a68 9.6.0 cited
On Wed, Jul 29, 2020 at 10:46 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> Thanks, please find the rebased patch set.
>
Few comments on v44-0001-Implement-streaming-mode-in-ReorderBuffer:
============================================================
1.
+-- streaming with subxact, nothing in main
+BEGIN;
+savepoint s1;
+SELECT 'msg5' FROM pg_logical_emit_message(true, 'test', repeat('a', 50));
+INSERT INTO stream_test SELECT repeat('a', 2000) || g.i FROM
generate_series(1, 35) g(i);
+TRUNCATE table stream_test;
+rollback to s1;
+INSERT INTO stream_test SELECT repeat('a', 10) || g.i FROM
generate_series(1, 20) g(i);
+COMMIT;
Is the above comment true? Because it seems to me that Insert is
getting streamed in the main transaction.
2.
+<programlisting>
+postgres[33712]=#* SELECT * FROM
pg_logical_slot_get_changes('test_slot', NULL, NULL, 'stream-changes',
'1');
+ lsn | xid | data
+-----------+-----+--------------------------------------------------
+ 0/16B21F8 | 503 | opening a streamed block for transaction TXN 503
+ 0/16B21F8 | 503 | streaming change for TXN 503
+ 0/16B2300 | 503 | streaming change for TXN 503
+ 0/16B2408 | 503 | streaming change for TXN 503
+ 0/16BEBA0 | 503 | closing a streamed block for transaction TXN 503
+ 0/16B21F8 | 503 | opening a streamed block for transaction TXN 503
+ 0/16BECA8 | 503 | streaming change for TXN 503
+ 0/16BEDB0 | 503 | streaming change for TXN 503
+ 0/16BEEB8 | 503 | streaming change for TXN 503
+ 0/16BEBA0 | 503 | closing a streamed block for transaction TXN 503
+(10 rows)
+</programlisting>
+ </para>
+
Is the above example correct? Because we should include XID in the
stream message only when include_xids option is specified.
3.
/*
- * Queue a change into a transaction so it can be replayed upon commit.
+ * Record the partial change for the streaming of in-progress transactions. We
+ * can stream only complete changes so if we have a partial change like toast
+ * table insert or speculative then we mark such a 'txn' so that it can't be
+ * streamed.
/speculative then/speculative insert then
4. I think we can explain the problems (like we can see the wrong
tuple or see two versions of the same tuple or whatever else wrong can
happen, if possible with some example) related to concurrent aborts
somewhere in comments.
--
With Regards,
Amit Kapila.