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

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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/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@mail.gmail.com
This commit is contained in:
Amit Kapila
2021-07-14 07:33:50 +05:30
parent 6c9c283166
commit a8fd13cab0
43 changed files with 2382 additions and 191 deletions
Download Patch File Download Diff File Expand all files Collapse all files

73
src/include/replication/logicalproto.h
View File

@@ -13,6 +13,7 @@
#ifndef LOGICAL_PROTO_H
#define LOGICAL_PROTO_H
#include "access/xact.h"
#include "replication/reorderbuffer.h"
#include "utils/rel.h"
@@ -26,12 +27,16 @@
* connect time.
*
* LOGICALREP_PROTO_STREAM_VERSION_NUM is the minimum protocol version with
* support for streaming large transactions.
* support for streaming large transactions. Introduced in PG14.
*
* LOGICALREP_PROTO_TWOPHASE_VERSION_NUM is the minimum protocol version with
* support for two-phase commit decoding (at prepare time). Introduced in PG15.
*/
#define LOGICALREP_PROTO_MIN_VERSION_NUM 1
#define LOGICALREP_PROTO_VERSION_NUM 1
#define LOGICALREP_PROTO_STREAM_VERSION_NUM 2
#define LOGICALREP_PROTO_MAX_VERSION_NUM LOGICALREP_PROTO_STREAM_VERSION_NUM
#define LOGICALREP_PROTO_TWOPHASE_VERSION_NUM 3
#define LOGICALREP_PROTO_MAX_VERSION_NUM LOGICALREP_PROTO_TWOPHASE_VERSION_NUM
/*
* Logical message types
@@ -55,6 +60,10 @@ typedef enum LogicalRepMsgType
LOGICAL_REP_MSG_RELATION = 'R',
LOGICAL_REP_MSG_TYPE = 'Y',
LOGICAL_REP_MSG_MESSAGE = 'M',
LOGICAL_REP_MSG_BEGIN_PREPARE = 'b',
LOGICAL_REP_MSG_PREPARE = 'P',
LOGICAL_REP_MSG_COMMIT_PREPARED = 'K',
LOGICAL_REP_MSG_ROLLBACK_PREPARED = 'r',
LOGICAL_REP_MSG_STREAM_START = 'S',
LOGICAL_REP_MSG_STREAM_END = 'E',
LOGICAL_REP_MSG_STREAM_COMMIT = 'c',
@@ -122,6 +131,48 @@ typedef struct LogicalRepCommitData
TimestampTz committime;
} LogicalRepCommitData;
/*
* Prepared transaction protocol information for begin_prepare, and prepare.
*/
typedef struct LogicalRepPreparedTxnData
{
XLogRecPtr prepare_lsn;
XLogRecPtr end_lsn;
TimestampTz prepare_time;
TransactionId xid;
char gid[GIDSIZE];
} LogicalRepPreparedTxnData;
/*
* Prepared transaction protocol information for commit prepared.
*/
typedef struct LogicalRepCommitPreparedTxnData
{
XLogRecPtr commit_lsn;
XLogRecPtr end_lsn;
TimestampTz commit_time;
TransactionId xid;
char gid[GIDSIZE];
} LogicalRepCommitPreparedTxnData;
/*
* Rollback Prepared transaction protocol information. The prepare information
* prepare_end_lsn and prepare_time are used to check if the downstream has
* received this prepared transaction in which case it can apply the rollback,
* otherwise, it can skip the rollback operation. The gid alone is not
* sufficient because the downstream node can have a prepared transaction with
* same identifier.
*/
typedef struct LogicalRepRollbackPreparedTxnData
{
XLogRecPtr prepare_end_lsn;
XLogRecPtr rollback_end_lsn;
TimestampTz prepare_time;
TimestampTz rollback_time;
TransactionId xid;
char gid[GIDSIZE];
} LogicalRepRollbackPreparedTxnData;
extern void logicalrep_write_begin(StringInfo out, ReorderBufferTXN *txn);
extern void logicalrep_read_begin(StringInfo in,
LogicalRepBeginData *begin_data);
@@ -129,6 +180,24 @@ extern void logicalrep_write_commit(StringInfo out, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
extern void logicalrep_read_commit(StringInfo in,
LogicalRepCommitData *commit_data);
extern void logicalrep_write_begin_prepare(StringInfo out, ReorderBufferTXN *txn);
extern void logicalrep_read_begin_prepare(StringInfo in,
LogicalRepPreparedTxnData *begin_data);
extern void logicalrep_write_prepare(StringInfo out, ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
extern void logicalrep_read_prepare(StringInfo in,
LogicalRepPreparedTxnData *prepare_data);
extern void logicalrep_write_commit_prepared(StringInfo out, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
extern void logicalrep_read_commit_prepared(StringInfo in,
LogicalRepCommitPreparedTxnData *prepare_data);
extern void logicalrep_write_rollback_prepared(StringInfo out, ReorderBufferTXN *txn,
XLogRecPtr prepare_end_lsn,
TimestampTz prepare_time);
extern void logicalrep_read_rollback_prepared(StringInfo in,
LogicalRepRollbackPreparedTxnData *rollback_data);
extern void logicalrep_write_origin(StringInfo out, const char *origin,
XLogRecPtr origin_lsn);
extern char *logicalrep_read_origin(StringInfo in, XLogRecPtr *origin_lsn);