Following patch implements COPY ... FROM ... LOCK as discussed earlier
this year on these threads:
http://archives.postgresql.org/pgsql-hackers/2005-06/msg00069.php
http://archives.postgresql.org/pgsql-hackers/2005-06/msg00075.php
The purpose of the new command is to make an explicit request to run
COPY without producing WAL records (i.e. no logging), so as to improve
the performance of data loads. (This is the first of a number of COPY
performance optimizations, discussed on -hackers).
Default COPY is unchanged.
LOCK option takes an EXCLUSIVE lock (but perhaps that should be a SHARE
ROW EXCLUSIVE?), allowing it to block out CREATE INDEX builds and
VACUUM.
LOCK option will also cause writing of WAL records to be skipped when
XLogArchivingActive() and there are no indexes.
The implementation refactors the code used by CTAS for syncing the data
to disk once command is complete; COPY and CTAS now both use that code.
COPY .. LOCK doesn't write any XLog records as was previously suggested.
My train of thought: After some thought, no other heap-based xlog action
would leave the table in a consistent state after failure. Nobody wants
to see a random single row in the table. I looked into UPDATEing the
last row loaded to generate an xlog rec but it would be difficult to do
that without being horribly kludgy. I looked at adding a new xlog
action, but there is only one slot left for a heap-based xlog action, so
that seemed unwise. I wrote this using an RM_XLOG xlrec, but that
doesn't actually trigger a commit write (I discover). I've simply set a
flag to tell the transaction to record the commit anyway. That was
already there in heapam.c anyway, but just for temp relations; I've
changed the name of the variable to indicate what it does now, across a
number of files.
(It is also arguable that I should implement a WAL record that truncates
the file back down to the starting size, in the event of a failure. I'm
not sure where we were on that; there seem to be comments both in favour
and against that idea. I can see the use for that, so I'll be happy to
add that also, if we agree there is no danger.)
I've added a few lock options onto the copy.sql test script, but not
added (yet) a full suite of testing.
No docs, yet.
Short performance test shown below for 10^6 rows, one col table.
1. Normal COPY 4.5s 11.4s 6.0s 6.1s
2. COPY LOCK 3.0s 2.7s 2.8s 2.7s
with postgresql.conf all default apart from: checkpoint_segments=30
This test was an "all in cache" test. The improvement is substantial,
but the numbers above are best case, IMHO: I would expect only 10-40%
improvement for larger loads in the general case.
Short output shown below, with checkpoint_segments=3, so timings for the
standard non-LOCK COPY probably include checkpoint time also.
=======================================================
postgres=# create table ctest as select
generate_series(1,1000000)::integer as col1;
SELECT
postgres=# copy ctest to '/usr/local/pgsql/ctest.data';
COPY
postgres=# truncate ctest;
TRUNCATE TABLE
Time: 41.343 ms
postgres=# copy ctest from '/usr/local/pgsql/ctest.data';
COPY
Time: 7111.205 ms
postgres=# truncate ctest;
TRUNCATE TABLE
Time: 23.175 ms
postgres=# copy ctest from '/usr/local/pgsql/ctest.data' lock;
COPY
Time: 2992.482 ms
postgres=# truncate ctest;
TRUNCATE TABLE
Time: 8.306 ms
postgres=# copy ctest from '/usr/local/pgsql/ctest.data';
COPY
Time: 7433.166 ms
Best Regards, Simon Riggs
Index: src/backend/access/heap/heapam.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/access/heap/heapam.c,v
retrieving revision 1.205
diff -c -r1.205 heapam.c
*** src/backend/access/heap/heapam.c 26 Nov 2005 05:03:06 -0000 1.205
--- src/backend/access/heap/heapam.c 10 Dec 2005 10:54:58 -0000
***************
*** 28,33 ****
--- 28,34 ----
* heap_update - replace a tuple in a relation with another tuple
* heap_markpos - mark scan position
* heap_restrpos - restore position to marked location
+ * heap_sync - sync heap, for when no WAL has been written
*
* NOTES
* This file contains the heap_ routines which implement
***************
*** 49,54 ****
--- 50,56 ----
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/procarray.h"
+ #include "storage/smgr.h"
#include "utils/inval.h"
#include "utils/relcache.h"
***************
*** 1335,1342 ****
* non-temp relation. Safe usage of this behavior requires that we arrange
* that all new tuples go into new pages not containing any tuples from other
* transactions, that the relation gets fsync'd before commit, and that the
! * transaction emits at least one WAL record to ensure RecordTransactionCommit
! * will decide to WAL-log the commit.
*
* use_fsm is passed directly to RelationGetBufferForTuple, which see for
* more info.
--- 1337,1345 ----
* non-temp relation. Safe usage of this behavior requires that we arrange
* that all new tuples go into new pages not containing any tuples from other
* transactions, that the relation gets fsync'd before commit, and that the
! * transaction emits at least one WAL record or must mark
! * MyXactMustRecordCommitIfAny=true to ensure RecordTransactionCommit will
! * decide to WAL-log the commit. (see heap_sync() comments also)
*
* use_fsm is passed directly to RelationGetBufferForTuple, which see for
* more info.
***************
*** 1413,1419 ****
if (relation->rd_istemp)
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
else if (use_wal)
{
--- 1416,1422 ----
if (relation->rd_istemp)
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
else if (use_wal)
{
***************
*** 1731,1737 ****
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 1734,1740 ----
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 2172,2178 ****
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2175,2181 ----
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 2674,2680 ****
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2677,2683 ----
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 3456,3458 ****
--- 3459,3490 ----
else
strcat(buf, "UNKNOWN");
}
+
+ /* ----------------
+ * heap_sync - sync a heap, for use when no WAL has been written
+ *
+ * ----------------
+ */
+ void
+ heap_sync(Relation rel, bool needToRecordCommit)
+ {
+ /*
+ * If our transaction has avoided writing WAL up to now,
+ * we need to force the changes to be written to disk then make
+ * commit record visible in clog, so other users can view these changes
+ */
+ if (needToRecordCommit)
+ MyXactMustRecordCommitIfAny = true;
+
+ if (!rel->rd_istemp)
+ {
+ /*
+ * If we skipped using WAL, and it's not a temp relation,
+ * we must force the relation down to disk before it's
+ * safe to commit the transaction. This requires forcing
+ * out any dirty buffers and then doing a forced fsync.
+ */
+ FlushRelationBuffers(rel);
+ smgrimmedsync(rel->rd_smgr);
+ }
+ }
Index: src/backend/access/transam/xact.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/access/transam/xact.c,v
retrieving revision 1.216
diff -c -r1.216 xact.c
*** src/backend/access/transam/xact.c 22 Nov 2005 18:17:07 -0000 1.216
--- src/backend/access/transam/xact.c 10 Dec 2005 10:55:02 -0000
***************
*** 669,675 ****
* all. (This test includes the effects of subtransactions, so the
* presence of committed subxacts need not alone force a write.)
*/
! if (MyXactMadeXLogEntry || MyXactMadeTempRelUpdate || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
bool madeTCentries;
--- 669,675 ----
* all. (This test includes the effects of subtransactions, so the
* presence of committed subxacts need not alone force a write.)
*/
! if (MyXactMadeXLogEntry || MyXactMustRecordCommitIfAny || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
bool madeTCentries;
***************
*** 782,788 ****
* crash the clog update might be lost. This is okay because no one
* else will ever care whether we committed.
*/
! if (madeTCentries || MyXactMadeTempRelUpdate)
{
TransactionIdCommit(xid);
/* to avoid race conditions, the parent must commit first */
--- 782,788 ----
* crash the clog update might be lost. This is okay because no one
* else will ever care whether we committed.
*/
! if (madeTCentries || MyXactMustRecordCommitIfAny)
{
TransactionIdCommit(xid);
/* to avoid race conditions, the parent must commit first */
***************
*** 799,805 ****
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMadeTempRelUpdate = false;
/* And clean up local data */
if (rels)
--- 799,805 ----
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMustRecordCommitIfAny = false;
/* And clean up local data */
if (rels)
***************
*** 933,939 ****
* dirtied these variables, then RecordTransactionCommit will have to do
* the full pushup anyway...)
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate)
{
TransactionId xid = GetCurrentTransactionId();
--- 933,939 ----
* dirtied these variables, then RecordTransactionCommit will have to do
* the full pushup anyway...)
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMustRecordCommitIfAny)
{
TransactionId xid = GetCurrentTransactionId();
***************
*** 973,979 ****
* recording the transaction abort at all. No one will ever care that it
* aborted. (These tests cover our whole transaction tree.)
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
--- 973,979 ----
* recording the transaction abort at all. No one will ever care that it
* aborted. (These tests cover our whole transaction tree.)
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMustRecordCommitIfAny || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
***************
*** 1056,1062 ****
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMadeTempRelUpdate = false;
/* And clean up local data */
if (rels)
--- 1056,1062 ----
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMustRecordCommitIfAny = false;
/* And clean up local data */
if (rels)
***************
*** 1173,1179 ****
* aborted, because they didn't mark themselves as subcommitted in the
* first place; see the optimization in RecordSubTransactionCommit.
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate || nrels > 0)
{
START_CRIT_SECTION();
--- 1173,1179 ----
* aborted, because they didn't mark themselves as subcommitted in the
* first place; see the optimization in RecordSubTransactionCommit.
*/
! if (MyLastRecPtr.xrecoff != 0 || MyXactMustRecordCommitIfAny || nrels > 0)
{
START_CRIT_SECTION();
***************
*** 1728,1734 ****
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMadeTempRelUpdate = false;
/*
* Let others know about no transaction in progress by me. This has to be
--- 1728,1734 ----
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
! MyXactMustRecordCommitIfAny = false;
/*
* Let others know about no transaction in progress by me. This has to be
Index: src/backend/access/transam/xlog.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/access/transam/xlog.c,v
retrieving revision 1.223
diff -c -r1.223 xlog.c
*** src/backend/access/transam/xlog.c 22 Nov 2005 18:17:07 -0000 1.223
--- src/backend/access/transam/xlog.c 10 Dec 2005 10:55:08 -0000
***************
*** 232,245 ****
* make any XLOG record, since we don't care about recovering the state of
* the temp rel after a crash. However, we will still need to remember
* whether our transaction committed or aborted in that case. So, we must
! * set MyXactMadeTempRelUpdate true to indicate that the XID will be of
* interest later.
*/
XLogRecPtr MyLastRecPtr = {0, 0};
bool MyXactMadeXLogEntry = false;
! bool MyXactMadeTempRelUpdate = false;
/*
* ProcLastRecPtr points to the start of the last XLOG record inserted by the
--- 232,245 ----
* make any XLOG record, since we don't care about recovering the state of
* the temp rel after a crash. However, we will still need to remember
* whether our transaction committed or aborted in that case. So, we must
! * set MyXactMustRecordCommitIfAny true to indicate that the XID will be of
* interest later.
*/
XLogRecPtr MyLastRecPtr = {0, 0};
bool MyXactMadeXLogEntry = false;
! bool MyXactMustRecordCommitIfAny = false;
/*
* ProcLastRecPtr points to the start of the last XLOG record inserted by the
Index: src/backend/commands/copy.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/commands/copy.c,v
retrieving revision 1.255
diff -c -r1.255 copy.c
*** src/backend/commands/copy.c 22 Nov 2005 18:17:08 -0000 1.255
--- src/backend/commands/copy.c 10 Dec 2005 10:55:11 -0000
***************
*** 110,115 ****
--- 110,116 ----
bool oids; /* include OIDs? */
bool csv_mode; /* Comma Separated Value format? */
bool header_line; /* CSV header line? */
+ bool useLock; /* use LOCK? */
char *null_print; /* NULL marker string (server encoding!) */
int null_print_len; /* length of same */
char *delim; /* column delimiter (must be 1 byte) */
***************
*** 654,659 ****
--- 655,661 ----
char *filename = stmt->filename;
bool is_from = stmt->is_from;
bool pipe = (stmt->filename == NULL);
+ LOCKMODE lockMode;
List *attnamelist = stmt->attlist;
List *force_quote = NIL;
List *force_notnull = NIL;
***************
*** 685,690 ****
--- 687,700 ----
errmsg("conflicting or redundant options")));
cstate->oids = intVal(defel->arg);
}
+ else if (strcmp(defel->defname, "lock") == 0)
+ {
+ if (cstate->useLock)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("conflicting or redundant options")));
+ cstate->useLock = intVal(defel->arg);
+ }
else if (strcmp(defel->defname, "delimiter") == 0)
{
if (cstate->delim)
***************
*** 854,861 ****
errmsg("CSV quote character must not appear in the NULL specification")));
/* Open and lock the relation, using the appropriate lock type. */
! cstate->rel = heap_openrv(relation,
! (is_from ? RowExclusiveLock : AccessShareLock));
/* check read-only transaction */
if (XactReadOnly && is_from &&
--- 864,879 ----
errmsg("CSV quote character must not appear in the NULL specification")));
/* Open and lock the relation, using the appropriate lock type. */
! if (is_from)
! {
! if (cstate->useLock)
! lockMode = ExclusiveLock;
! else
! lockMode = RowExclusiveLock;
! }
! else
! lockMode = AccessShareLock;
! cstate->rel = heap_openrv(relation, lockMode);
/* check read-only transaction */
if (XactReadOnly && is_from &&
***************
*** 1465,1470 ****
--- 1483,1489 ----
ExprContext *econtext; /* used for ExecEvalExpr for default atts */
MemoryContext oldcontext = CurrentMemoryContext;
ErrorContextCallback errcontext;
+ bool use_wal = true; /* By default, we use WAL to log db changes */
tupDesc = RelationGetDescr(cstate->rel);
attr = tupDesc->attrs;
***************
*** 1647,1652 ****
--- 1666,1678 ----
econtext->ecxt_param_exec_vals = (ParamExecData *)
palloc0(sizeof(ParamExecData));
+ /*
+ * If LOCK option is used, we can skip WAL-logging the insertions,
+ * unless PITR is in use
+ */
+ if (resultRelInfo->ri_NumIndices == 0)
+ use_wal = !(cstate->useLock) || XLogArchivingActive();
+
/* Initialize state variables */
cstate->fe_eof = false;
cstate->eol_type = EOL_UNKNOWN;
***************
*** 1909,1915 ****
ExecConstraints(resultRelInfo, slot, estate);
/* OK, store the tuple and create index entries for it */
! simple_heap_insert(cstate->rel, tuple);
if (resultRelInfo->ri_NumIndices > 0)
ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
--- 1935,1941 ----
ExecConstraints(resultRelInfo, slot, estate);
/* OK, store the tuple and create index entries for it */
! heap_insert(cstate->rel, tuple, GetCurrentCommandId(), use_wal, use_wal);
if (resultRelInfo->ri_NumIndices > 0)
ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
***************
*** 1919,1924 ****
--- 1945,1956 ----
}
}
+ /*
+ * If we used LOCK and thereby skipped writing WAL, then we need to sync
+ */
+ if (!use_wal)
+ heap_sync(cstate->rel, true);
+
/* Done, clean up */
error_context_stack = errcontext.previous;
Index: src/backend/commands/vacuum.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/commands/vacuum.c,v
retrieving revision 1.319
diff -c -r1.319 vacuum.c
*** src/backend/commands/vacuum.c 22 Nov 2005 18:17:09 -0000 1.319
--- src/backend/commands/vacuum.c 10 Dec 2005 10:55:14 -0000
***************
*** 2454,2460 ****
* No XLOG record, but still need to flag that XID exists on
* disk
*/
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2454,2460 ----
* No XLOG record, but still need to flag that XID exists on
* disk
*/
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 2610,2616 ****
/*
* No XLOG record, but still need to flag that XID exists on disk
*/
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2610,2616 ----
/*
* No XLOG record, but still need to flag that XID exists on disk
*/
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 2714,2720 ****
/*
* No XLOG record, but still need to flag that XID exists on disk
*/
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2714,2720 ----
/*
* No XLOG record, but still need to flag that XID exists on disk
*/
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
***************
*** 2914,2920 ****
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 2914,2920 ----
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
Index: src/backend/commands/vacuumlazy.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/commands/vacuumlazy.c,v
retrieving revision 1.63
diff -c -r1.63 vacuumlazy.c
*** src/backend/commands/vacuumlazy.c 22 Nov 2005 18:17:09 -0000 1.63
--- src/backend/commands/vacuumlazy.c 10 Dec 2005 10:55:15 -0000
***************
*** 583,589 ****
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMadeTempRelUpdate = true;
}
END_CRIT_SECTION();
--- 583,589 ----
else
{
/* No XLOG record, but still need to flag that XID exists on disk */
! MyXactMustRecordCommitIfAny = true;
}
END_CRIT_SECTION();
Index: src/backend/executor/execMain.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/executor/execMain.c,v
retrieving revision 1.262
diff -c -r1.262 execMain.c
*** src/backend/executor/execMain.c 2 Dec 2005 20:03:40 -0000 1.262
--- src/backend/executor/execMain.c 10 Dec 2005 10:55:17 -0000
***************
*** 996,1009 ****
* If we skipped using WAL, and it's not a temp relation, we must
* force the relation down to disk before it's safe to commit the
* transaction. This requires forcing out any dirty buffers and then
! * doing a forced fsync.
*/
! if (!estate->es_into_relation_use_wal &&
! !estate->es_into_relation_descriptor->rd_istemp)
! {
! FlushRelationBuffers(estate->es_into_relation_descriptor);
! smgrimmedsync(estate->es_into_relation_descriptor->rd_smgr);
! }
heap_close(estate->es_into_relation_descriptor, NoLock);
}
--- 996,1005 ----
* If we skipped using WAL, and it's not a temp relation, we must
* force the relation down to disk before it's safe to commit the
* transaction. This requires forcing out any dirty buffers and then
! * doing a forced fsync. We've written WAL for the CREATE TABLE
! * however, so no need to force writing the commit.
*/
! heap_sync(estate->es_into_relation_descriptor, false);
heap_close(estate->es_into_relation_descriptor, NoLock);
}
Index: src/backend/parser/gram.y
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/parser/gram.y,v
retrieving revision 2.516
diff -c -r2.516 gram.y
*** src/backend/parser/gram.y 28 Nov 2005 04:35:31 -0000 2.516
--- src/backend/parser/gram.y 10 Dec 2005 10:55:25 -0000
***************
*** 1635,1640 ****
--- 1635,1644 ----
{
$$ = makeDefElem("force_notnull", (Node *)$4);
}
+ | LOCK_P
+ {
+ $$ = makeDefElem("lock", (Node *)makeInteger(TRUE));
+ }
;
/* The following exist for backward compatibility */
Index: src/include/access/heapam.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/access/heapam.h,v
retrieving revision 1.105
diff -c -r1.105 heapam.h
*** src/include/access/heapam.h 15 Oct 2005 02:49:42 -0000 1.105
--- src/include/access/heapam.h 10 Dec 2005 10:55:27 -0000
***************
*** 220,223 ****
--- 220,225 ----
extern HeapTuple heap_addheader(int natts, bool withoid,
Size structlen, void *structure);
+ extern void heap_sync(Relation relation, bool writeXLog);
+
#endif /* HEAPAM_H */
Index: src/include/access/xlog.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/access/xlog.h,v
retrieving revision 1.69
diff -c -r1.69 xlog.h
*** src/include/access/xlog.h 15 Oct 2005 02:49:42 -0000 1.69
--- src/include/access/xlog.h 10 Dec 2005 10:55:27 -0000
***************
*** 132,138 ****
extern bool InRecovery;
extern XLogRecPtr MyLastRecPtr;
extern bool MyXactMadeXLogEntry;
! extern bool MyXactMadeTempRelUpdate;
extern XLogRecPtr ProcLastRecEnd;
/* these variables are GUC parameters related to XLOG */
--- 132,138 ----
extern bool InRecovery;
extern XLogRecPtr MyLastRecPtr;
extern bool MyXactMadeXLogEntry;
! extern bool MyXactMustRecordCommitIfAny;
extern XLogRecPtr ProcLastRecEnd;
/* these variables are GUC parameters related to XLOG */
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