Add support for prepared transactions to built-in logical replication.

To add support for streaming transactions at prepare time into the
built-in logical replication, we need to do the following things:

* Modify the output plugin (pgoutput) to implement the new two-phase API
callbacks, by leveraging the extended replication protocol.

* Modify the replication apply worker, to properly handle two-phase
transactions by replaying them on prepare.

* Add a new SUBSCRIPTION option "two_phase" to allow users to enable
two-phase transactions. We enable the two_phase once the initial data sync
is over.

We however must explicitly disable replication of two-phase transactions
during replication slot creation, even if the plugin supports it. We
don't need to replicate the changes accumulated during this phase,
and moreover, we don't have a replication connection open so we don't know
where to send the data anyway.

The streaming option is not allowed with this new two_phase option. This
can be done as a separate patch.

We don't allow to toggle two_phase option of a subscription because it can
lead to an inconsistent replica. For the same reason, we don't allow to
refresh the publication once the two_phase is enabled for a subscription
unless copy_data option is false.

Author: Peter Smith, Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Sawada Masahiko, Vignesh C, Dilip Kumar, Takamichi Osumi, Greg Nancarrow
Tested-By: Haiying Tang
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@mail.gmail.com

1 files changed, 6 insertions, 6 deletions

diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index de1b6926581..e5cd84e85e4 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -339,7 +339,7 @@ pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.commit_time));
 
 	OutputPluginWrite(ctx, true);
 }
@@ -382,7 +382,7 @@ pg_decode_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.prepare_time));
 
 	OutputPluginWrite(ctx, true);
 }
@@ -404,7 +404,7 @@ pg_decode_commit_prepared_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.commit_time));
 
 	OutputPluginWrite(ctx, true);
 }
@@ -428,7 +428,7 @@ pg_decode_rollback_prepared_txn(LogicalDecodingContext *ctx,
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.commit_time));
 
 	OutputPluginWrite(ctx, true);
 }
@@ -853,7 +853,7 @@ pg_decode_stream_prepare(LogicalDecodingContext *ctx,
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.prepare_time));
 
 	OutputPluginWrite(ctx, true);
 }
@@ -882,7 +882,7 @@ pg_decode_stream_commit(LogicalDecodingContext *ctx,
 
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, " (at %s)",
-						 timestamptz_to_str(txn->commit_time));
+						 timestamptz_to_str(txn->xact_time.commit_time));
 
 	OutputPluginWrite(ctx, true);
 }