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Add a xid argument to the filter_prepare callback for output plugins. 

Along with gid, this provides a different way to identify the transaction.
The users that use xid in some way to prepare the transactions can use it
to filter prepare transactions. The later commands COMMIT PREPARED or
ROLLBACK PREPARED carries both identifiers, providing an output plugin the
choice of what to use.

Author: Markus Wanner
Reviewed-by: Vignesh C, Amit Kapila
Discussion: https://postgr.es/m/ee280000-7355-c4dc-e47b-2436e7be959c@enterprisedb.com
This commit is contained in:
Amit Kapila 2021-03-30 10:34:43 +05:30
parent bc2797ebb1
commit f64ea6dc5c
6 changed files with 38 additions and 21 deletions
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4
contrib/test_decoding/test_decoding.c
View File

@ -77,6 +77,7 @@ static void pg_decode_message(LogicalDecodingContext *ctx,
bool transactional, const char *prefix,
Size sz, const char *message);
static bool pg_decode_filter_prepare(LogicalDecodingContext *ctx,
TransactionId xid,
const char *gid);
static void pg_decode_begin_prepare_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
@ -440,7 +441,8 @@ pg_decode_rollback_prepared_txn(LogicalDecodingContext *ctx,
* substring, then we filter it out.
*/
static bool
pg_decode_filter_prepare(LogicalDecodingContext *ctx, const char *gid)
pg_decode_filter_prepare(LogicalDecodingContext *ctx, TransactionId xid,
const char *gid)
{
if (strstr(gid, "_nodecode") != NULL)
return true;

29
doc/src/sgml/logicaldecoding.sgml
View File

@ -794,20 +794,25 @@ typedef void (*LogicalDecodeMessageCB) (struct LogicalDecodingContext *ctx,
<command>COMMIT PREPARED</command> time. To signal that
decoding should be skipped, return <literal>true</literal>;
<literal>false</literal> otherwise. When the callback is not
defined, <literal>false</literal> is assumed (i.e. nothing is
filtered).
defined, <literal>false</literal> is assumed (i.e. no filtering, all
transactions using two-phase commit are decoded in two phases as well).
<programlisting>
typedef bool (*LogicalDecodeFilterPrepareCB) (struct LogicalDecodingContext *ctx,
TransactionId xid,
const char *gid);
</programlisting>
The <parameter>ctx</parameter> parameter has the same contents as for the
other callbacks. The <parameter>gid</parameter> is the identifier that later
identifies this transaction for <command>COMMIT PREPARED</command> or
<command>ROLLBACK PREPARED</command>.
The <parameter>ctx</parameter> parameter has the same contents as for
the other callbacks. The parameters <parameter>xid</parameter>
and <parameter>gid</parameter> provide two different ways to identify
the transaction. The later <command>COMMIT PREPARED</command> or
<command>ROLLBACK PREPARED</command> carries both identifiers,
providing an output plugin the choice of what to use.
</para>
<para>
The callback has to provide the same static answer for a given
<parameter>gid</parameter> every time it is called.
The callback may be invoked multiple times per transaction to decode
and must provide the same static answer for a given pair of
<parameter>xid</parameter> and <parameter>gid</parameter> every time
it is called.
</para>
</sect3>
@ -1219,9 +1224,11 @@ stream_commit_cb(...); &lt;-- commit of the streamed transaction
</para>
<para>
Optionally the output plugin can specify a name pattern in the
<function>filter_prepare_cb</function> and transactions with gid containing
that name pattern will not be decoded as a two-phase commit transaction.
Optionally the output plugin can define filtering rules via
<function>filter_prepare_cb</function> to decode only specific transaction
in two phases. This can be achieved by pattern matching on the
<parameter>gid</parameter> or via lookups using the
<parameter>xid</parameter>.
</para>
<para>

17
src/backend/replication/logical/decode.c
View File

@ -80,7 +80,8 @@ static void DecodePrepare(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
static void DecodeXLogTuple(char *data, Size len, ReorderBufferTupleBuf *tup);
/* helper functions for decoding transactions */
static inline bool FilterPrepare(LogicalDecodingContext *ctx, const char *gid);
static inline bool FilterPrepare(LogicalDecodingContext *ctx,
TransactionId xid, const char *gid);
static bool DecodeTXNNeedSkip(LogicalDecodingContext *ctx,
XLogRecordBuffer *buf, Oid dbId,
RepOriginId origin_id);
@ -271,7 +272,8 @@ DecodeXactOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* doesn't filter the transaction at prepare time.
*/
if (info == XLOG_XACT_COMMIT_PREPARED)
two_phase = !(FilterPrepare(ctx, parsed.twophase_gid));
two_phase = !(FilterPrepare(ctx, xid,
parsed.twophase_gid));
DecodeCommit(ctx, buf, &parsed, xid, two_phase);
break;
@ -298,7 +300,8 @@ DecodeXactOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* doesn't filter the transaction at prepare time.
*/
if (info == XLOG_XACT_ABORT_PREPARED)
two_phase = !(FilterPrepare(ctx, parsed.twophase_gid));
two_phase = !(FilterPrepare(ctx, xid,
parsed.twophase_gid));
DecodeAbort(ctx, buf, &parsed, xid, two_phase);
break;
@ -355,7 +358,8 @@ DecodeXactOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* manner iff output plugin supports two-phase commits and
* doesn't filter the transaction at prepare time.
*/
if (FilterPrepare(ctx, parsed.twophase_gid))
if (FilterPrepare(ctx, parsed.twophase_xid,
parsed.twophase_gid))
{
ReorderBufferProcessXid(reorder, parsed.twophase_xid,
buf->origptr);
@ -581,7 +585,8 @@ DecodeHeapOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* this transaction as a regular commit later.
*/
static inline bool
FilterPrepare(LogicalDecodingContext *ctx, const char *gid)
FilterPrepare(LogicalDecodingContext *ctx, TransactionId xid,
const char *gid)
{
/*
* Skip if decoding of two-phase transactions at PREPARE time is not
@ -599,7 +604,7 @@ FilterPrepare(LogicalDecodingContext *ctx, const char *gid)
if (ctx->callbacks.filter_prepare_cb == NULL)
return false;
return filter_prepare_cb_wrapper(ctx, gid);
return filter_prepare_cb_wrapper(ctx, xid, gid);
}
static inline bool

5
src/backend/replication/logical/logical.c
View File

@ -1083,7 +1083,8 @@ truncate_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
}
bool
filter_prepare_cb_wrapper(LogicalDecodingContext *ctx, const char *gid)
filter_prepare_cb_wrapper(LogicalDecodingContext *ctx, TransactionId xid,
const char *gid)
{
LogicalErrorCallbackState state;
ErrorContextCallback errcallback;
@ -1104,7 +1105,7 @@ filter_prepare_cb_wrapper(LogicalDecodingContext *ctx, const char *gid)
ctx->accept_writes = false;
/* do the actual work: call callback */
ret = ctx->callbacks.filter_prepare_cb(ctx, gid);
ret = ctx->callbacks.filter_prepare_cb(ctx, xid, gid);
/* Pop the error context stack */
error_context_stack = errcallback.previous;

3
src/include/replication/logical.h
View File

@ -125,7 +125,8 @@ extern void LogicalIncreaseRestartDecodingForSlot(XLogRecPtr current_lsn,
XLogRecPtr restart_lsn);
extern void LogicalConfirmReceivedLocation(XLogRecPtr lsn);
extern bool filter_prepare_cb_wrapper(LogicalDecodingContext *ctx, const char *gid);
extern bool filter_prepare_cb_wrapper(LogicalDecodingContext *ctx,
TransactionId xid, const char *gid);
extern bool filter_by_origin_cb_wrapper(LogicalDecodingContext *ctx, RepOriginId origin_id);
extern void ResetLogicalStreamingState(void);
extern void UpdateDecodingStats(LogicalDecodingContext *ctx);

1
src/include/replication/output_plugin.h
View File

@ -106,6 +106,7 @@ typedef void (*LogicalDecodeShutdownCB) (struct LogicalDecodingContext *ctx);
* and sent as usual transaction.
*/
typedef bool (*LogicalDecodeFilterPrepareCB) (struct LogicalDecodingContext *ctx,
TransactionId xid,
const char *gid);
/*