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Add prepare API support for streaming transactions in logical replication.

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Commit a8fd13cab0 added support for prepared transactions to built-in
logical replication via a new option "two_phase" for a subscription. The
"two_phase" option was not allowed with the existing streaming option.

This commit permits the combination of "streaming" and "two_phase"
subscription options. It extends the pgoutput plugin and the subscriber
side code to add the prepare API for streaming transactions which will
apply the changes accumulated in the spool-file at prepare time.

Author: Peter Smith and Ajin Cherian
Reviewed-by: Vignesh C, Amit Kapila, Greg Nancarrow
Tested-By: Haiying Tang
Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
Discussion: https://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
This commit is contained in:
Amit Kapila
2021-08-04 07:47:06 +05:30
parent 6424337073
commit 63cf61cdeb
12 changed files with 667 additions and 79 deletions
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33
src/backend/replication/pgoutput/pgoutput.c
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@@ -71,6 +71,8 @@ static void pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
static void pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr prepare_lsn);
static bool publications_valid;
static bool in_streaming;
@@ -175,7 +177,7 @@ _PG_output_plugin_init(OutputPluginCallbacks *cb)
cb->stream_message_cb = pgoutput_message;
cb->stream_truncate_cb = pgoutput_truncate;
/* transaction streaming - two-phase commit */
cb->stream_prepare_cb = NULL;
cb->stream_prepare_cb = pgoutput_stream_prepare_txn;
}
static void
@@ -280,17 +282,6 @@ parse_output_parameters(List *options, PGOutputData *data)
}
else
elog(ERROR, "unrecognized pgoutput option: %s", defel->defname);
/*
* Do additional checking for the disallowed combination of two_phase
* and streaming. While streaming and two_phase can theoretically be
* supported, it needs more analysis to allow them together.
*/
if (data->two_phase && data->streaming)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("%s and %s are mutually exclusive options",
"two_phase", "streaming")));
}
}
@@ -1029,6 +1020,24 @@ pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
cleanup_rel_sync_cache(txn->xid, true);
}
/*
* PREPARE callback (for streaming two-phase commit).
*
* Notify the downstream to prepare the transaction.
*/
static void
pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn)
{
Assert(rbtxn_is_streamed(txn));
OutputPluginUpdateProgress(ctx);
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_stream_prepare(ctx->out, txn, prepare_lsn);
OutputPluginWrite(ctx, true);
}
/*
* Initialize the relation schema sync cache for a decoding session.
*