postgres

Author SHA1 Message Date

Author	SHA1	Message	Date
Amit Kapila	7259736a6e	Implement streaming mode in ReorderBuffer. Instead of serializing the transaction to disk after reaching the logical_decoding_work_mem limit in memory, we consume the changes we have in memory and invoke stream API methods added by commit `45fdc9738b`. However, sometimes if we have incomplete toast or speculative insert we spill to the disk because we can't generate the complete tuple and stream. And, as soon as we get the complete tuple we stream the transaction including the serialized changes. We can do this incremental processing thanks to having assignments (associating subxact with toplevel xacts) in WAL right away, and thanks to logging the invalidation messages at each command end. These features are added by commits `0bead9af48` and `c55040ccd0` respectively. Now that we can stream in-progress transactions, the concurrent aborts may cause failures when the output plugin consults catalogs (both system and user-defined). We handle such failures by returning ERRCODE_TRANSACTION_ROLLBACK sqlerrcode from system table scan APIs to the backend or WALSender decoding a specific uncommitted transaction. The decoding logic on the receipt of such a sqlerrcode aborts the decoding of the current transaction and continue with the decoding of other transactions. We have ReorderBufferTXN pointer in each ReorderBufferChange by which we know which xact it belongs to. The output plugin can use this to decide which changes to discard in case of stream_abort_cb (e.g. when a subxact gets discarded). We also provide a new option via SQL APIs to fetch the changes being streamed. Author: Dilip Kumar, Tomas Vondra, Amit Kapila, Nikhil Sontakke Reviewed-by: Amit Kapila, Kuntal Ghosh, Ajin Cherian Tested-by: Neha Sharma, Mahendra Singh Thalor and Ajin Cherian Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com	6 years ago
Andres Freund	ef493055b6	Force synchronous commit to be enabled for all test_decoding tests. Without that the tests fail when forced to be run against a cluster with synchronous_commit = off (as the WAL might not yet be flushed to disk by the point logical decoding gets called, and thus the expected output breaks). Most tests already do that, add it to a few newer tests. Author: Andres Freund	7 years ago
Peter Eisentraut	5dfd1e5a66	Logical decoding of TRUNCATE Add a new WAL record type for TRUNCATE, which is only used when wal_level >= logical. (For physical replication, TRUNCATE is already replicated via SMGR records.) Add new callback for logical decoding output plugins to receive TRUNCATE actions. Author: Simon Riggs <simon@2ndquadrant.com> Author: Marco Nenciarini <marco.nenciarini@2ndquadrant.it> Author: Peter Eisentraut <peter.eisentraut@2ndquadrant.com> Reviewed-by: Petr Jelinek <petr.jelinek@2ndquadrant.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>	8 years ago

Amit Kapila

Implement streaming mode in ReorderBuffer.

Instead of serializing the transaction to disk after reaching the
logical_decoding_work_mem limit in memory, we consume the changes we have
in memory and invoke stream API methods added by commit 45fdc9738b.
However, sometimes if we have incomplete toast or speculative insert we
spill to the disk because we can't generate the complete tuple and stream.
And, as soon as we get the complete tuple we stream the transaction
including the serialized changes.

We can do this incremental processing thanks to having assignments
(associating subxact with toplevel xacts) in WAL right away, and
thanks to logging the invalidation messages at each command end. These
features are added by commits 0bead9af48 and c55040ccd0 respectively.

Now that we can stream in-progress transactions, the concurrent aborts
may cause failures when the output plugin consults catalogs (both system
and user-defined).

We handle such failures by returning ERRCODE_TRANSACTION_ROLLBACK
sqlerrcode from system table scan APIs to the backend or WALSender
decoding a specific uncommitted transaction. The decoding logic on the
receipt of such a sqlerrcode aborts the decoding of the current
transaction and continue with the decoding of other transactions.

We have ReorderBufferTXN pointer in each ReorderBufferChange by which we
know which xact it belongs to.  The output plugin can use this to decide
which changes to discard in case of stream_abort_cb (e.g. when a subxact
gets discarded).

We also provide a new option via SQL APIs to fetch the changes being
streamed.

Author: Dilip Kumar, Tomas Vondra, Amit Kapila, Nikhil Sontakke
Reviewed-by: Amit Kapila, Kuntal Ghosh, Ajin Cherian
Tested-by: Neha Sharma, Mahendra Singh Thalor and Ajin Cherian
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com

6 years ago

Andres Freund

ef493055b6

Force synchronous commit to be enabled for all test_decoding tests.

Without that the tests fail when forced to be run against a cluster
with synchronous_commit = off (as the WAL might not yet be flushed to
disk by the point logical decoding gets called, and thus the expected
output breaks). Most tests already do that, add it to a few newer tests.

Author: Andres Freund

7 years ago

Peter Eisentraut

5dfd1e5a66

Logical decoding of TRUNCATE

Add a new WAL record type for TRUNCATE, which is only used when
wal_level >= logical.  (For physical replication, TRUNCATE is already
replicated via SMGR records.)  Add new callback for logical decoding
output plugins to receive TRUNCATE actions.

Author: Simon Riggs <simon@2ndquadrant.com>
Author: Marco Nenciarini <marco.nenciarini@2ndquadrant.it>
Author: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>

8 years ago

3 Commits (0d91c52a8fc71bfe5664a13368e42e1dabc5fe78)