Hi,
attached is the newest version of the patch.
I removed the registry, renamed the 'send' to 'emit', documented the
callback parameters properly. I also added the test to ddl.sql for the
serialization and deserialization (and of course found a bug there) and
in general fixed all the stuff Andres reported.
(see more inline)
On 28/02/16 22:55, Andres Freund wrote:
+void
+ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn,
+ bool transactional, const
char *prefix, Size msg_sz,
+ const char *msg)
+{
+ ReorderBufferTXN *txn = NULL;
+
+ if (transactional)
+ {
+ ReorderBufferChange *change;
+
+ txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
+
+ Assert(xid != InvalidTransactionId);
+ Assert(txn != NULL);
+
+ change = ReorderBufferGetChange(rb);
+ change->action = REORDER_BUFFER_CHANGE_MESSAGE;
+ change->data.msg.transactional = true;
+ change->data.msg.prefix = pstrdup(prefix);
+ change->data.msg.message_size = msg_sz;
+ change->data.msg.message = palloc(msg_sz);
+ memcpy(change->data.msg.message, msg, msg_sz);
+
+ ReorderBufferQueueChange(rb, xid, lsn, change);
+ }
+ else
+ {
+ rb->message(rb, txn, lsn, transactional, prefix, msg_sz, msg);
+ }
+}
This approach prohibts catalog access when processing a nontransaction
message as there's no snapshot set up.
Hmm I do see usefulness in having snapshot, although I wonder if that does
not kill the point of non-transactional messages.
I don't see how it would? It'd obviously have to be the catalog/historic
snapshot a transaction would have had if it started in that moment in
the original WAL stream?
Question is then though which snapshot should the message see,
base_snapshot of transaction?
Well, there'll not be a transaction, but something like snapbuild.c's
->snapshot ought to do the trick.
Ok I added interface which returns either existing snapshot or makes new
one, seems like the most reasonable thing to do to me.
That would mean we'd have to call SnapBuildProcessChange for
non-transactional messages which we currently avoid. Alternatively we
could probably invent lighter version of that interface that would
just make sure builder->snapshot is valid and if not then build it
I think the latter is probably the direction we should go in.
I am honestly sure if that's a win or not.
I think it'll be confusing (bug inducing) if there's no snapshot for
non-transactional messages but for transactional ones, and it'll
severely limit the usefulness of the interface.
Nono, I meant I am not sure if special interface is a win over just
using SnapBuildProcessChange() in practice.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
From 2f037a757d9cec09f04457d82cdd1256b8255b78 Mon Sep 17 00:00:00 2001
From: Petr Jelinek <pjmodos@pjmodos.net>
Date: Wed, 24 Feb 2016 17:02:36 +0100
Subject: [PATCH] Logical Decoding Messages
---
contrib/test_decoding/Makefile | 2 +-
contrib/test_decoding/expected/ddl.out | 21 ++++--
contrib/test_decoding/expected/messages.out | 56 ++++++++++++++++
contrib/test_decoding/sql/ddl.sql | 3 +-
contrib/test_decoding/sql/messages.sql | 17 +++++
contrib/test_decoding/test_decoding.c | 19 ++++++
doc/src/sgml/func.sgml | 45 +++++++++++++
doc/src/sgml/logicaldecoding.sgml | 37 +++++++++++
src/backend/access/rmgrdesc/Makefile | 4 +-
src/backend/access/rmgrdesc/logicalmsgdesc.c | 41 ++++++++++++
src/backend/access/transam/rmgr.c | 1 +
src/backend/replication/logical/Makefile | 2 +-
src/backend/replication/logical/decode.c | 49 ++++++++++++++
src/backend/replication/logical/logical.c | 38 +++++++++++
src/backend/replication/logical/logicalfuncs.c | 27 ++++++++
src/backend/replication/logical/message.c | 87 +++++++++++++++++++++++++
src/backend/replication/logical/reorderbuffer.c | 67 +++++++++++++++++++
src/backend/replication/logical/snapbuild.c | 19 ++++++
src/bin/pg_xlogdump/rmgrdesc.c | 1 +
src/include/access/rmgrlist.h | 1 +
src/include/catalog/pg_proc.h | 4 ++
src/include/replication/logicalfuncs.h | 2 +
src/include/replication/message.h | 41 ++++++++++++
src/include/replication/output_plugin.h | 13 ++++
src/include/replication/reorderbuffer.h | 21 ++++++
src/include/replication/snapbuild.h | 2 +
26 files changed, 608 insertions(+), 12 deletions(-)
create mode 100644 contrib/test_decoding/expected/messages.out
create mode 100644 contrib/test_decoding/sql/messages.sql
create mode 100644 src/backend/access/rmgrdesc/logicalmsgdesc.c
create mode 100644 src/backend/replication/logical/message.c
create mode 100644 src/include/replication/message.h
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index a362e69..8fdcfbc 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -38,7 +38,7 @@ submake-test_decoding:
$(MAKE) -C $(top_builddir)/contrib/test_decoding
REGRESSCHECKS=ddl rewrite toast permissions decoding_in_xact decoding_into_rel \
- binary prepared replorigin
+ binary prepared replorigin messages
regresscheck: | submake-regress submake-test_decoding temp-install
$(MKDIR_P) regression_output
diff --git a/contrib/test_decoding/expected/ddl.out b/contrib/test_decoding/expected/ddl.out
index 57a1289..4d13ad4 100644
--- a/contrib/test_decoding/expected/ddl.out
+++ b/contrib/test_decoding/expected/ddl.out
@@ -220,11 +220,17 @@ SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'inc
(7 rows)
/*
- * check that disk spooling works
+ * check that disk spooling works (also for logical messages)
*/
BEGIN;
CREATE TABLE tr_etoomuch (id serial primary key, data int);
INSERT INTO tr_etoomuch(data) SELECT g.i FROM generate_series(1, 10234) g(i);
+SELECT 'tx logical msg' FROM pg_logical_emit_message(true, 'test', 'tx logical msg');
+ ?column?
+----------------
+ tx logical msg
+(1 row)
+
DELETE FROM tr_etoomuch WHERE id < 5000;
UPDATE tr_etoomuch SET data = - data WHERE id > 5000;
COMMIT;
@@ -233,12 +239,13 @@ SELECT count(*), min(data), max(data)
FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')
GROUP BY substring(data, 1, 24)
ORDER BY 1,2;
- count | min | max
--------+-------------------------------------------------+------------------------------------------------------------------------
- 1 | BEGIN | BEGIN
- 1 | COMMIT | COMMIT
- 20467 | table public.tr_etoomuch: DELETE: id[integer]:1 | table public.tr_etoomuch: UPDATE: id[integer]:9999 data[integer]:-9999
-(3 rows)
+ count | min | max
+-------+-----------------------------------------------------------------------+------------------------------------------------------------------------
+ 1 | BEGIN | BEGIN
+ 1 | COMMIT | COMMIT
+ 1 | message: transactional: 1 prefix: test, sz: 14 content:tx logical msg | message: transactional: 1 prefix: test, sz: 14 content:tx logical msg
+ 20467 | table public.tr_etoomuch: DELETE: id[integer]:1 | table public.tr_etoomuch: UPDATE: id[integer]:9999 data[integer]:-9999
+(4 rows)
-- check that a large, spooled, upsert works
INSERT INTO tr_etoomuch (id, data)
diff --git a/contrib/test_decoding/expected/messages.out b/contrib/test_decoding/expected/messages.out
new file mode 100644
index 0000000..7fa8256
--- /dev/null
+++ b/contrib/test_decoding/expected/messages.out
@@ -0,0 +1,56 @@
+-- predictability
+SET synchronous_commit = on;
+SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
+ ?column?
+----------
+ init
+(1 row)
+
+SELECT 'msg1' FROM pg_logical_emit_message(true, 'test', 'msg1');
+ ?column?
+----------
+ msg1
+(1 row)
+
+SELECT 'msg2' FROM pg_logical_emit_message(false, 'test', 'msg2');
+ ?column?
+----------
+ msg2
+(1 row)
+
+BEGIN;
+SELECT 'msg3' FROM pg_logical_emit_message(true, 'test', 'msg3');
+ ?column?
+----------
+ msg3
+(1 row)
+
+SELECT 'msg4' FROM pg_logical_emit_message(false, 'test', 'msg4');
+ ?column?
+----------
+ msg4
+(1 row)
+
+SELECT 'msg5' FROM pg_logical_emit_message(true, 'test', 'msg5');
+ ?column?
+----------
+ msg5
+(1 row)
+
+COMMIT;
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
+ data
+------------------------------------------------------------
+ message: transactional: 1 prefix: test, sz: 4 content:msg1
+ message: transactional: 0 prefix: test, sz: 4 content:msg2
+ message: transactional: 0 prefix: test, sz: 4 content:msg4
+ message: transactional: 1 prefix: test, sz: 4 content:msg3
+ message: transactional: 1 prefix: test, sz: 4 content:msg5
+(5 rows)
+
+SELECT 'init' FROM pg_drop_replication_slot('regression_slot');
+ ?column?
+----------
+ init
+(1 row)
+
diff --git a/contrib/test_decoding/sql/ddl.sql b/contrib/test_decoding/sql/ddl.sql
index e311c59..2f31784 100644
--- a/contrib/test_decoding/sql/ddl.sql
+++ b/contrib/test_decoding/sql/ddl.sql
@@ -108,11 +108,12 @@ DELETE FROM tr_pkey;
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
/*
- * check that disk spooling works
+ * check that disk spooling works (also for logical messages)
*/
BEGIN;
CREATE TABLE tr_etoomuch (id serial primary key, data int);
INSERT INTO tr_etoomuch(data) SELECT g.i FROM generate_series(1, 10234) g(i);
+SELECT 'tx logical msg' FROM pg_logical_emit_message(true, 'test', 'tx logical msg');
DELETE FROM tr_etoomuch WHERE id < 5000;
UPDATE tr_etoomuch SET data = - data WHERE id > 5000;
COMMIT;
diff --git a/contrib/test_decoding/sql/messages.sql b/contrib/test_decoding/sql/messages.sql
new file mode 100644
index 0000000..8744eb6
--- /dev/null
+++ b/contrib/test_decoding/sql/messages.sql
@@ -0,0 +1,17 @@
+-- predictability
+SET synchronous_commit = on;
+
+SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
+
+SELECT 'msg1' FROM pg_logical_emit_message(true, 'test', 'msg1');
+SELECT 'msg2' FROM pg_logical_emit_message(false, 'test', 'msg2');
+
+BEGIN;
+SELECT 'msg3' FROM pg_logical_emit_message(true, 'test', 'msg3');
+SELECT 'msg4' FROM pg_logical_emit_message(false, 'test', 'msg4');
+SELECT 'msg5' FROM pg_logical_emit_message(true, 'test', 'msg5');
+COMMIT;
+
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
+
+SELECT 'init' FROM pg_drop_replication_slot('regression_slot');
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 4cf808f..6395ffd 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -21,6 +21,7 @@
#include "replication/output_plugin.h"
#include "replication/logical.h"
+#include "replication/message.h"
#include "replication/origin.h"
#include "utils/builtins.h"
@@ -63,6 +64,10 @@ static void pg_decode_change(LogicalDecodingContext *ctx,
ReorderBufferChange *change);
static bool pg_decode_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id);
+static void pg_decode_message(LogicalDecodingContext *ctx,
+ ReorderBufferTXN *txn, XLogRecPtr message_lsn,
+ bool transactional, const char *prefix,
+ Size sz, const char *message);
void
_PG_init(void)
@@ -82,6 +87,7 @@ _PG_output_plugin_init(OutputPluginCallbacks *cb)
cb->commit_cb = pg_decode_commit_txn;
cb->filter_by_origin_cb = pg_decode_filter;
cb->shutdown_cb = pg_decode_shutdown;
+ cb->message_cb = pg_decode_message;
}
@@ -471,3 +477,16 @@ pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
OutputPluginWrite(ctx, true);
}
+
+static void
+pg_decode_message(LogicalDecodingContext *ctx,
+ ReorderBufferTXN *txn, XLogRecPtr lsn,
+ bool transactional, const char *prefix,
+ Size sz, const char *message)
+{
+ OutputPluginPrepareWrite(ctx, true);
+ appendStringInfo(ctx->out, "message: transactional: %d prefix: %s, sz: %zu content:",
+ transactional, prefix, sz);
+ appendBinaryStringInfo(ctx->out, message, sz);
+ OutputPluginWrite(ctx, true);
+}
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index c0b94bc..1201f9f 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -17769,6 +17769,51 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
</entry>
</row>
+ <row>
+ <entry id="pg-logical-emit-message-text">
+ <indexterm>
+ <primary>pg_logical_emit_message</primary>
+ </indexterm>
+ <literal><function>pg_logical_emit_message(<parameter>transactional</parameter> <type>bool</type>, <parameter>prefix</parameter> <type>text</type>, <parameter>content</parameter> <type>text</type>)</function></literal>
+ </entry>
+ <entry>
+ void
+ </entry>
+ <entry>
+ Write text logical decoding message. This can be used to pass generic
+ messages to logical decoding plugins through WAL. The parameter
+ <parameter>transactional</parameter> specifies if the message should
+ be part of current transaction or if it should be written immediately
+ and decoded as soon as the logical decoding reads the record. The
+ <parameter>prefix</parameter> is textual prefix used by the logical
+ decoding plugins to easily recognize interesting messages for them.
+ The <parameter>content</parameter> is the text of the message.
+ </entry>
+ </row>
+
+ <row>
+ <entry id="pg-logical-emit-message-bytea">
+ <indexterm>
+ <primary>>pg_logical_emit_message</primary>
+ </indexterm>
+ <literal><function>>pg_logical_emit_message(<parameter>transactional</parameter> <type>bool</type>, <parameter>prefix</parameter> <type>text</type>, <parameter>content</parameter> <type>bytea</type>)</function></literal>
+ </entry>
+ <entry>
+ void
+ </entry>
+ <entry>
+ Write binary logical decoding message. This can be used to pass generic
+ messages to logical decoding plugins through WAL. The parameter
+ <parameter>transactional</parameter> specifies if the message should
+ be part of current transaction or if it should be written immediately
+ and decoded as soon as the logical decoding reads the record. The
+ <parameter>prefix</parameter> is textual prefix used by the logical
+ decoding plugins to easily recognize interesting messages for them.
+ The <parameter>content</parameter> is the binary content of the
+ message.
+ </entry>
+ </row>
+
</tbody>
</tgroup>
</table>
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index e841348..93ffcfb 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -363,6 +363,7 @@ typedef struct OutputPluginCallbacks
LogicalDecodeBeginCB begin_cb;
LogicalDecodeChangeCB change_cb;
LogicalDecodeCommitCB commit_cb;
+ LogicalDecodeMessageCB message_cb;
LogicalDecodeFilterByOriginCB filter_by_origin_cb;
LogicalDecodeShutdownCB shutdown_cb;
} OutputPluginCallbacks;
@@ -602,6 +603,42 @@ typedef bool (*LogicalDecodeFilterByOriginCB) (
more efficient.
</para>
</sect3>
+
+ <sect3 id="logicaldecoding-output-plugin-message">
+ <title>Generic Message Callback</title>
+
+ <para>
+ The optional <function>message_cb</function> callback is called whenever
+ a logical decoding message has been decoded.
+<programlisting>
+typedef void (*LogicalDecodeMessageCB) (
+ struct LogicalDecodingContext *,
+ ReorderBufferTXN *txn,
+ XLogRecPtr message_lsn,
+ bool transactional,
+ const char *prefix,
+ Size message_size,
+ const char *message
+);
+</programlisting>
+ The <parameter>ctx</parameter> and <parameter>txn</parameter> parameters
+ have the same contents as for the <function>begin_cb</function> with the
+ difference that <parameter>txn</parameter> is null for non-transactional
+ messages. The <parameter>lsn</parameter> has WAL position of the message.
+ The <parameter>transactional</parameter> says if he message was sent as
+ transactional or not. The <parameter>prefix</parameter> is arbitrary
+ textual prefix which can be used for identifying interesting messages
+ for the current plugin. And finally the <parameter>message</parameter>
+ parameter holds the actual message of <parameter>message_size</parameter>
+ size.
+ </para>
+ <para>
+ Extra care should be taken to ensure that the prefix the output plugin
+ considers interesting is unique. Using name of the extension or the
+ output plugin itself is often a good choice.
+ </para>
+ </sect3>
+
</sect2>
<sect2 id="logicaldecoding-output-plugin-output">
diff --git a/src/backend/access/rmgrdesc/Makefile b/src/backend/access/rmgrdesc/Makefile
index c72a1f2..723b4d8 100644
--- a/src/backend/access/rmgrdesc/Makefile
+++ b/src/backend/access/rmgrdesc/Makefile
@@ -9,8 +9,8 @@ top_builddir = ../../../..
include $(top_builddir)/src/Makefile.global
OBJS = brindesc.o clogdesc.o committsdesc.o dbasedesc.o gindesc.o gistdesc.o \
- hashdesc.o heapdesc.o mxactdesc.o nbtdesc.o relmapdesc.o \
- replorigindesc.o seqdesc.o smgrdesc.o spgdesc.o \
+ hashdesc.o heapdesc.o logicalmsgdesc.o mxactdesc.o nbtdesc.o \
+ relmapdesc.o replorigindesc.o seqdesc.o smgrdesc.o spgdesc.o \
standbydesc.o tblspcdesc.o xactdesc.o xlogdesc.o
include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/rmgrdesc/logicalmsgdesc.c b/src/backend/access/rmgrdesc/logicalmsgdesc.c
new file mode 100644
index 0000000..e5e84dd
--- /dev/null
+++ b/src/backend/access/rmgrdesc/logicalmsgdesc.c
@@ -0,0 +1,41 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicalmsgdesc.c
+ * rmgr descriptor routines for replication/logical/message.c
+ *
+ * Portions Copyright (c) 2015-2016, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ * src/backend/access/rmgrdesc/logicalmsgdesc.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "replication/message.h"
+
+void
+logicalmsg_desc(StringInfo buf, XLogReaderState *record)
+{
+ char *rec = XLogRecGetData(record);
+ uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+ if (info == XLOG_LOGICAL_MESSAGE)
+ {
+ xl_logical_message *xlrec = (xl_logical_message *) rec;
+
+ appendStringInfo(buf, "%s message size %zu bytes",
+ xlrec->transactional ? "transactional" : "nontransactional",
+ xlrec->message_size);
+ }
+}
+
+const char *
+logicalmsg_identify(uint8 info)
+{
+ if (info & ~XLR_INFO_MASK == XLOG_LOGICAL_MESSAGE)
+ return "MESSAGE";
+
+ return NULL;
+}
diff --git a/src/backend/access/transam/rmgr.c b/src/backend/access/transam/rmgr.c
index 7c4d773..1a42121 100644
--- a/src/backend/access/transam/rmgr.c
+++ b/src/backend/access/transam/rmgr.c
@@ -23,6 +23,7 @@
#include "commands/dbcommands_xlog.h"
#include "commands/sequence.h"
#include "commands/tablespace.h"
+#include "replication/message.h"
#include "replication/origin.h"
#include "storage/standby.h"
#include "utils/relmapper.h"
diff --git a/src/backend/replication/logical/Makefile b/src/backend/replication/logical/Makefile
index 8adea13..1d7ca06 100644
--- a/src/backend/replication/logical/Makefile
+++ b/src/backend/replication/logical/Makefile
@@ -14,7 +14,7 @@ include $(top_builddir)/src/Makefile.global
override CPPFLAGS := -I$(srcdir) $(CPPFLAGS)
-OBJS = decode.o logical.o logicalfuncs.o reorderbuffer.o origin.o \
+OBJS = decode.o logical.o logicalfuncs.o message.o origin.o reorderbuffer.o \
snapbuild.o
include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 88c3a49..368a2f6 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -39,6 +39,7 @@
#include "replication/decode.h"
#include "replication/logical.h"
+#include "replication/message.h"
#include "replication/reorderbuffer.h"
#include "replication/origin.h"
#include "replication/snapbuild.h"
@@ -58,6 +59,7 @@ static void DecodeHeapOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
static void DecodeHeap2Op(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
static void DecodeXactOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
static void DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
+static void DecodeLogicalMsgOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
/* individual record(group)'s handlers */
static void DecodeInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf);
@@ -115,6 +117,10 @@ LogicalDecodingProcessRecord(LogicalDecodingContext *ctx, XLogReaderState *recor
DecodeHeapOp(ctx, &buf);
break;
+ case RM_LOGICALMSG_ID:
+ DecodeLogicalMsgOp(ctx, &buf);
+ break;
+
/*
* Rmgrs irrelevant for logical decoding; they describe stuff not
* represented in logical decoding. Add new rmgrs in rmgrlist.h's
@@ -431,6 +437,49 @@ DecodeHeapOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
}
}
+/*
+ * Handle rmgr LOGICALMSG_ID records for DecodeRecordIntoReorderBuffer().
+ */
+static void
+DecodeLogicalMsgOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
+{
+ SnapBuild *builder = ctx->snapshot_builder;
+ XLogReaderState *r = buf->record;
+ uint8 info = XLogRecGetInfo(r) & ~XLR_INFO_MASK;
+ xl_logical_message *message;
+
+ if (info != XLOG_LOGICAL_MESSAGE)
+ elog(ERROR, "unexpected RM_LOGICALMSG_ID record type: %u", info);
+
+ message = (xl_logical_message *) XLogRecGetData(r);
+
+ if (message->transactional)
+ {
+ if (!SnapBuildProcessChange(builder, XLogRecGetXid(r), buf->origptr))
+ return;
+
+ ReorderBufferQueueMessage(ctx->reorder, XLogRecGetXid(r),
+ buf->endptr,
+ message->message, /* first part of message is prefix */
+ message->message_size,
+ message->message + message->prefix_size);
+ }
+ else if (SnapBuildCurrentState(builder) == SNAPBUILD_CONSISTENT &&
+ !SnapBuildXactNeedsSkip(builder, buf->origptr))
+ {
+ volatile Snapshot snapshot_now;
+ ReorderBuffer *rb = ctx->reorder;
+
+ /* setup snapshot to allow catalog access */
+ snapshot_now = SnapBuildGetOrBuildSnapshot(builder, XLogRecGetXid(r));
+ SetupHistoricSnapshot(snapshot_now, NULL);
+ rb->message(rb, NULL, buf->origptr, false, message->message,
+ message->message_size,
+ message->message + message->prefix_size);
+ TeardownHistoricSnapshot(false);
+ }
+}
+
static inline bool
FilterByOrigin(LogicalDecodingContext *ctx, RepOriginId origin_id)
{
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 2e6d3f9..3974cd4 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -62,6 +62,9 @@ static void commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void change_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change);
+static void message_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
+ XLogRecPtr message_lsn, bool transactional,
+ const char *prefix, Size sz, const char *message);
static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, char *plugin);
@@ -178,6 +181,7 @@ StartupDecodingContext(List *output_plugin_options,
ctx->reorder->begin = begin_cb_wrapper;
ctx->reorder->apply_change = change_cb_wrapper;
ctx->reorder->commit = commit_cb_wrapper;
+ ctx->reorder->message = message_cb_wrapper;
ctx->out = makeStringInfo();
ctx->prepare_write = prepare_write;
@@ -702,6 +706,40 @@ filter_by_origin_cb_wrapper(LogicalDecodingContext *ctx, RepOriginId origin_id)
return ret;
}
+static void message_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
+ XLogRecPtr message_lsn,
+ bool transactional, const char *prefix,
+ Size sz, const char *message)
+{
+ LogicalDecodingContext *ctx = cache->private_data;
+ LogicalErrorCallbackState state;
+ ErrorContextCallback errcallback;
+
+ if (ctx->callbacks.message_cb == NULL)
+ return;
+
+ /* Push callback + info on the error context stack */
+ state.ctx = ctx;
+ state.callback_name = "message";
+ state.report_location = message_lsn;
+ errcallback.callback = output_plugin_error_callback;
+ errcallback.arg = (void *) &state;
+ errcallback.previous = error_context_stack;
+ error_context_stack = &errcallback;
+
+ /* set output state */
+ ctx->accept_writes = true;
+ ctx->write_xid = txn != NULL ? txn->xid : InvalidTransactionId;
+ ctx->write_location = message_lsn;
+
+ /* do the actual work: call callback */
+ ctx->callbacks.message_cb(ctx, txn, message_lsn, transactional,
+ prefix, sz, message);
+
+ /* Pop the error context stack */
+ error_context_stack = errcallback.previous;
+}
+
/*
* Set the required catalog xmin horizon for historic snapshots in the current
* replication slot.
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index f789fc1..fe22daa 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -24,6 +24,8 @@
#include "access/xlog_internal.h"
#include "access/xlogutils.h"
+#include "access/xact.h"
+
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
@@ -41,6 +43,7 @@
#include "replication/decode.h"
#include "replication/logical.h"
#include "replication/logicalfuncs.h"
+#include "replication/message.h"
#include "storage/fd.h"
@@ -363,3 +366,27 @@ pg_logical_slot_peek_binary_changes(PG_FUNCTION_ARGS)
{
return pg_logical_slot_get_changes_guts(fcinfo, false, true);
}
+
+
+/*
+ * SQL function returning the changestream in binary, only peeking ahead.
+ */
+Datum
+pg_logical_emit_message_bytea(PG_FUNCTION_ARGS)
+{
+ bool transactional = PG_GETARG_BOOL(0);
+ char *prefix = text_to_cstring(PG_GETARG_TEXT_PP(1));
+ bytea *data = PG_GETARG_BYTEA_PP(2);
+ XLogRecPtr lsn;
+
+ lsn = LogLogicalMessage(prefix, VARDATA_ANY(data), VARSIZE_ANY_EXHDR(data),
+ transactional);
+ PG_RETURN_LSN(lsn);
+}
+
+Datum
+pg_logical_emit_message_text(PG_FUNCTION_ARGS)
+{
+ /* bytea and text are compatible */
+ return pg_logical_emit_message_bytea(fcinfo);
+}
diff --git a/src/backend/replication/logical/message.c b/src/backend/replication/logical/message.c
new file mode 100644
index 0000000..214be45
--- /dev/null
+++ b/src/backend/replication/logical/message.c
@@ -0,0 +1,87 @@
+/*-------------------------------------------------------------------------
+ *
+ * message.c
+ * Generic logical messages.
+ *
+ * Copyright (c) 2013-2016, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/backend/replication/logical/message.c
+ *
+ * NOTES
+ *
+ * Generic logical messages allow XLOG logging of arbitrary binary blobs that
+ * get passed to the logical decoding plugin. In normal XLOG processing they
+ * are same as NOOP.
+ *
+ * These messages can be either transactional or non-transactional.
+ * Transactional messages are part of current transaction and will be sent to
+ * decoding plugin using in a same way as DML operations.
+ * Non-transactional messages are sent to the plugin at the time when the
+ * logical decoding reads them from XLOG.
+ *
+ * Every message carries prefix to avoid conflicts between different decoding
+ * plugins. The prefix has to be registered before the message using that
+ * prefix can be written to XLOG. The prefix can be registered exactly once to
+ * avoid situation where multiple third party extensions try to use same
+ * prefix.
+ *
+ * ---------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/xact.h"
+
+#include "catalog/indexing.h"
+
+#include "nodes/execnodes.h"
+
+#include "replication/message.h"
+#include "replication/logical.h"
+
+#include "utils/memutils.h"
+
+/*
+ * Write logical decoding message into XLog.
+ */
+XLogRecPtr
+LogLogicalMessage(const char *prefix, const char *message, size_t size,
+ bool transactional)
+{
+ xl_logical_message xlrec;
+
+ /*
+ * Force xid to be allocated if we're emitting a transactional message.
+ */
+ if (transactional)
+ {
+ Assert(IsTransactionState());
+ GetCurrentTransactionId();
+ }
+
+ xlrec.transactional = transactional;
+ xlrec.prefix_size = strlen(prefix) + 1;
+ xlrec.message_size = size;
+
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfLogicalMessage);
+ XLogRegisterData((char *) prefix, xlrec.prefix_size);
+ XLogRegisterData((char *) message, size);
+
+ return XLogInsert(RM_LOGICALMSG_ID, XLOG_LOGICAL_MESSAGE);
+}
+
+/*
+ * Redo is basically just noop for logical decoding messages.
+ */
+void
+logicalmsg_redo(XLogReaderState *record)
+{
+ uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+ if (info != XLOG_LOGICAL_MESSAGE)
+ elog(PANIC, "logicalmsg_redo: unknown op code %u", info);
+
+ /* This is only interesting for logical decoding, see decode.c. */
+}
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 78acced..0312346 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -414,6 +414,14 @@ ReorderBufferReturnChange(ReorderBuffer *rb, ReorderBufferChange *change)
change->data.tp.oldtuple = NULL;
}
break;
+ case REORDER_BUFFER_CHANGE_MESSAGE:
+ if (change->data.msg.prefix != NULL)
+ pfree(change->data.msg.prefix);
+ change->data.msg.prefix = NULL;
+ if (change->data.msg.message != NULL)
+ pfree(change->data.msg.message);
+ change->data.msg.message = NULL;
+ break;
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
if (change->data.snapshot)
{
@@ -599,6 +607,26 @@ ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn,
ReorderBufferCheckSerializeTXN(rb, txn);
}
+void
+ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn,
+ const char *prefix, Size msg_sz, const char *msg)
+{
+ ReorderBufferChange *change;
+
+ Assert(xid != InvalidTransactionId);
+
+ change = ReorderBufferGetChange(rb);
+ change->action = REORDER_BUFFER_CHANGE_MESSAGE;
+ change->data.msg.transactional = true;
+ change->data.msg.prefix = pstrdup(prefix);
+ change->data.msg.message_size = msg_sz;
+ change->data.msg.message = palloc(msg_sz);
+ memcpy(change->data.msg.message, msg, msg_sz);
+
+ ReorderBufferQueueChange(rb, xid, lsn, change);
+}
+
+
static void
AssertTXNLsnOrder(ReorderBuffer *rb)
{
@@ -1465,6 +1493,14 @@ ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
specinsert = change;
break;
+ case REORDER_BUFFER_CHANGE_MESSAGE:
+ rb->message(rb, txn, change->lsn,
+ change->data.msg.transactional,
+ change->data.msg.prefix,
+ change->data.msg.message_size,
+ change->data.msg.message);
+ break;
+
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
/* get rid of the old */
TeardownHistoricSnapshot(false);
@@ -2117,6 +2153,21 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
}
break;
}
+ case REORDER_BUFFER_CHANGE_MESSAGE:
+ {
+ char *data;
+ size_t prefix_size = strlen(change->data.msg.prefix) + 1;
+
+ sz += prefix_size + change->data.msg.message_size;
+ ReorderBufferSerializeReserve(rb, sz);
+
+ data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
+ memcpy(data, change->data.msg.prefix,
+ prefix_size);
+ memcpy(data + prefix_size, change->data.msg.message,
+ change->data.msg.message_size);
+ break;
+ }
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
{
Snapshot snap;
@@ -2354,6 +2405,22 @@ ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
data += len;
}
break;
+ case REORDER_BUFFER_CHANGE_MESSAGE:
+ {
+ Size message_size = change->data.msg.message_size;
+ /* prefix includes trailing zero */
+ Size prefix_size = strlen(data) + 1;
+
+ change->data.msg.prefix = MemoryContextAlloc(rb->context,
+ prefix_size);
+ memcpy(change->data.msg.prefix, data, prefix_size);
+ data += prefix_size;
+ change->data.msg.message = MemoryContextAlloc(rb->context,
+ message_size);
+ memcpy(change->data.msg.message, data, message_size);
+ data += message_size;
+ break;
+ }
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
{
Snapshot oldsnap;
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index ed823ec..d7829c3 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -605,6 +605,25 @@ SnapBuildExportSnapshot(SnapBuild *builder)
}
/*
+ * Ensure there is a snapshot and if not build one for current transaction.
+ */
+Snapshot
+SnapBuildGetOrBuildSnapshot(SnapBuild *builder, TransactionId xid)
+{
+ Assert(builder->state == SNAPBUILD_CONSISTENT);
+
+ /* only build a new snapshot if we don't have a prebuilt one */
+ if (builder->snapshot == NULL)
+ {
+ builder->snapshot = SnapBuildBuildSnapshot(builder, xid);
+ /* inrease refcount for the snapshot builder */
+ SnapBuildSnapIncRefcount(builder->snapshot);
+ }
+
+ return builder->snapshot;
+}
+
+/*
* Reset a previously SnapBuildExportSnapshot()'ed snapshot if there is
* any. Aborts the previously started transaction and resets the resource
* owner back to its original value.
diff --git a/src/bin/pg_xlogdump/rmgrdesc.c b/src/bin/pg_xlogdump/rmgrdesc.c
index f9cd395..6ba7f22 100644
--- a/src/bin/pg_xlogdump/rmgrdesc.c
+++ b/src/bin/pg_xlogdump/rmgrdesc.c
@@ -25,6 +25,7 @@
#include "commands/dbcommands_xlog.h"
#include "commands/sequence.h"
#include "commands/tablespace.h"
+#include "replication/message.h"
#include "replication/origin.h"
#include "rmgrdesc.h"
#include "storage/standbydefs.h"
diff --git a/src/include/access/rmgrlist.h b/src/include/access/rmgrlist.h
index fab912d..35c242d 100644
--- a/src/include/access/rmgrlist.h
+++ b/src/include/access/rmgrlist.h
@@ -45,3 +45,4 @@ PG_RMGR(RM_SPGIST_ID, "SPGist", spg_redo, spg_desc, spg_identify, spg_xlog_start
PG_RMGR(RM_BRIN_ID, "BRIN", brin_redo, brin_desc, brin_identify, NULL, NULL)
PG_RMGR(RM_COMMIT_TS_ID, "CommitTs", commit_ts_redo, commit_ts_desc, commit_ts_identify, NULL, NULL)
PG_RMGR(RM_REPLORIGIN_ID, "ReplicationOrigin", replorigin_redo, replorigin_desc, replorigin_identify, NULL, NULL)
+PG_RMGR(RM_LOGICALMSG_ID, "LogicalMessage", logicalmsg_redo, logicalmsg_desc, logicalmsg_identify, NULL, NULL)
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 62b9125..ff722fe 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -5084,6 +5084,10 @@ DATA(insert OID = 3784 ( pg_logical_slot_peek_changes PGNSP PGUID 12 1000 1000
DESCR("peek at changes from replication slot");
DATA(insert OID = 3785 ( pg_logical_slot_peek_binary_changes PGNSP PGUID 12 1000 1000 25 0 f f f f f t v u 4 0 2249 "19 3220 23 1009" "{19,3220,23,1009,3220,28,17}" "{i,i,i,v,o,o,o}" "{slot_name,upto_lsn,upto_nchanges,options,location,xid,data}" _null_ _null_ pg_logical_slot_peek_binary_changes _null_ _null_ _null_ ));
DESCR("peek at binary changes from replication slot");
+DATA(insert OID = 3577 ( pg_logical_emit_message PGNSP PGUID 12 1 0 0 0 f f f f f f v u 3 0 3220 "16 25 25" _null_ _null_ _null_ _null_ _null_ pg_logical_emit_message_text _null_ _null_ _null_ ));
+DESCR("emit a textual logical decoding message");
+DATA(insert OID = 3578 ( pg_logical_emit_message PGNSP PGUID 12 1 0 0 0 f f f f f f v u 3 0 3220 "16 25 17" _null_ _null_ _null_ _null_ _null_ pg_logical_emit_message_bytea _null_ _null_ _null_ ));
+DESCR("emit a binary logical decoding message");
/* event triggers */
DATA(insert OID = 3566 ( pg_event_trigger_dropped_objects PGNSP PGUID 12 10 100 0 0 f f f f t t s s 0 0 2249 "" "{26,26,23,16,16,16,25,25,25,25,1009,1009}" "{o,o,o,o,o,o,o,o,o,o,o,o}" "{classid, objid, objsubid, original, normal, is_temporary, object_type, schema_name, object_name, object_identity, address_names, address_args}" _null_ _null_ pg_event_trigger_dropped_objects _null_ _null_ _null_ ));
diff --git a/src/include/replication/logicalfuncs.h b/src/include/replication/logicalfuncs.h
index c87a1df..5540414 100644
--- a/src/include/replication/logicalfuncs.h
+++ b/src/include/replication/logicalfuncs.h
@@ -21,4 +21,6 @@ extern Datum pg_logical_slot_get_binary_changes(PG_FUNCTION_ARGS);
extern Datum pg_logical_slot_peek_changes(PG_FUNCTION_ARGS);
extern Datum pg_logical_slot_peek_binary_changes(PG_FUNCTION_ARGS);
+extern Datum pg_logical_emit_message_bytea(PG_FUNCTION_ARGS);
+extern Datum pg_logical_emit_message_text(PG_FUNCTION_ARGS);
#endif
diff --git a/src/include/replication/message.h b/src/include/replication/message.h
new file mode 100644
index 0000000..b1730c9
--- /dev/null
+++ b/src/include/replication/message.h
@@ -0,0 +1,41 @@
+/*-------------------------------------------------------------------------
+ * message.h
+ * Exports from replication/logical/message.c
+ *
+ * Copyright (c) 2013-2016, PostgreSQL Global Development Group
+ *
+ * src/include/replication/message.h
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_LOGICAL_MESSAGE_H
+#define PG_LOGICAL_MESSAGE_H
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "access/xlogreader.h"
+
+/*
+ * Generic logical decoding message wal record.
+ */
+typedef struct xl_logical_message
+{
+ bool transactional; /* is message transactional? */
+ size_t prefix_size; /* length of prefix */
+ size_t message_size; /* size of the message */
+ char message[FLEXIBLE_ARRAY_MEMBER]; /* message including the null
+ * terminated prefx of length
+ * prefix_size */
+} xl_logical_message;
+
+#define SizeOfLogicalMessage (offsetof(xl_logical_message, message))
+
+extern XLogRecPtr LogLogicalMessage(const char *prefix, const char *message,
+ size_t size, bool transactional);
+
+/* RMGR API*/
+#define XLOG_LOGICAL_MESSAGE 0x00
+void logicalmsg_redo(XLogReaderState *record);
+void logicalmsg_desc(StringInfo buf, XLogReaderState *record);
+const char *logicalmsg_identify(uint8 info);
+
+#endif /* PG_LOGICAL_MESSAGE_H */
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 577b12e..3a2ca98 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -74,6 +74,18 @@ typedef void (*LogicalDecodeCommitCB) (
XLogRecPtr commit_lsn);
/*
+ * Called for the generic logical decoding messages.
+ */
+typedef void (*LogicalDecodeMessageCB) (
+ struct LogicalDecodingContext *,
+ ReorderBufferTXN *txn,
+ XLogRecPtr message_lsn,
+ bool transactional,
+ const char *prefix,
+ Size message_size,
+ const char *message);
+
+/*
* Filter changes by origin.
*/
typedef bool (*LogicalDecodeFilterByOriginCB) (
@@ -96,6 +108,7 @@ typedef struct OutputPluginCallbacks
LogicalDecodeBeginCB begin_cb;
LogicalDecodeChangeCB change_cb;
LogicalDecodeCommitCB commit_cb;
+ LogicalDecodeMessageCB message_cb;
LogicalDecodeFilterByOriginCB filter_by_origin_cb;
LogicalDecodeShutdownCB shutdown_cb;
} OutputPluginCallbacks;
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index d33ea27..a3af5a6 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -51,6 +51,7 @@ enum ReorderBufferChangeType
REORDER_BUFFER_CHANGE_INSERT,
REORDER_BUFFER_CHANGE_UPDATE,
REORDER_BUFFER_CHANGE_DELETE,
+ REORDER_BUFFER_CHANGE_MESSAGE,
REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT,
REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID,
REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID,
@@ -95,6 +96,14 @@ typedef struct ReorderBufferChange
ReorderBufferTupleBuf *newtuple;
} tp;
+ struct
+ {
+ bool transactional;
+ char *prefix;
+ size_t message_size;
+ char *message;
+ } msg;
+
/* New snapshot, set when action == *_INTERNAL_SNAPSHOT */
Snapshot snapshot;
@@ -271,6 +280,15 @@ typedef void (*ReorderBufferCommitCB) (
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
+/* message callback signature */
+typedef void (*ReorderBufferMessageCB) (
+ ReorderBuffer *rb,
+ ReorderBufferTXN *txn,
+ XLogRecPtr message_lsn,
+ bool transactional,
+ const char *prefix, Size sz,
+ const char *message);
+
struct ReorderBuffer
{
/*
@@ -297,6 +315,7 @@ struct ReorderBuffer
ReorderBufferBeginCB begin;
ReorderBufferApplyChangeCB apply_change;
ReorderBufferCommitCB commit;
+ ReorderBufferMessageCB message;
/*
* Pointer that will be passed untouched to the callbacks.
@@ -347,6 +366,8 @@ ReorderBufferChange *ReorderBufferGetChange(ReorderBuffer *);
void ReorderBufferReturnChange(ReorderBuffer *, ReorderBufferChange *);
void ReorderBufferQueueChange(ReorderBuffer *, TransactionId, XLogRecPtr lsn, ReorderBufferChange *);
+void ReorderBufferQueueMessage(ReorderBuffer *, TransactionId, XLogRecPtr lsn,
+ const char *prefix, Size msg_sz, const char *msg);
void ReorderBufferCommit(ReorderBuffer *, TransactionId,
XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
TimestampTz commit_time, RepOriginId origin_id, XLogRecPtr origin_lsn);
diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h
index 75955af..c4127a1 100644
--- a/src/include/replication/snapbuild.h
+++ b/src/include/replication/snapbuild.h
@@ -63,6 +63,8 @@ extern const char *SnapBuildExportSnapshot(SnapBuild *snapstate);
extern void SnapBuildClearExportedSnapshot(void);
extern SnapBuildState SnapBuildCurrentState(SnapBuild *snapstate);
+extern Snapshot SnapBuildGetOrBuildSnapshot(SnapBuild *builder,
+ TransactionId xid);
extern bool SnapBuildXactNeedsSkip(SnapBuild *snapstate, XLogRecPtr ptr);
--
1.9.1
--
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