Renumber SnapshotNow and the other special snapshot codes so that
((Snapshot) NULL) can no longer be confused with a valid snapshot, as per my recent suggestion. Define a macro InvalidSnapshot for 0. Use InvalidSnapshot instead of SnapshotAny as the do-nothing special case for heap_update and heap_delete crosschecks; this seems a little cleaner even though the behavior is really the same.
This commit is contained in:
Tom Lane
parent
9835944e54
commit
493f72606b
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.173 2004/08/29 05:06:40 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.174 2004/09/11 18:28:32 tgl Exp $
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*
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*
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* INTERFACE ROUTINES
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@ -1262,7 +1262,7 @@ simple_heap_insert(Relation relation, HeapTuple tup)
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* tid - TID of tuple to be deleted
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* ctid - output parameter, used only for failure case (see below)
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* cid - delete command ID to use in verifying tuple visibility
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* crosscheck - if not SnapshotAny, also check tuple against this
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* crosscheck - if not InvalidSnapshot, also check tuple against this
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* wait - true if should wait for any conflicting update to commit/abort
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*
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* Normal, successful return value is HeapTupleMayBeUpdated, which
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@ -1274,7 +1274,8 @@ simple_heap_insert(Relation relation, HeapTuple tup)
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*/
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int
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heap_delete(Relation relation, ItemPointer tid,
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ItemPointer ctid, CommandId cid, Snapshot crosscheck, bool wait)
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ItemPointer ctid, CommandId cid,
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Snapshot crosscheck, bool wait)
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{
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ItemId lp;
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HeapTupleData tp;
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@ -1339,7 +1340,7 @@ l1:
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result = HeapTupleUpdated;
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}
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if (crosscheck != SnapshotAny && result == HeapTupleMayBeUpdated)
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if (crosscheck != InvalidSnapshot && result == HeapTupleMayBeUpdated)
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{
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/* Perform additional check for serializable RI updates */
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if (!HeapTupleSatisfiesSnapshot(tp.t_data, crosscheck))
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@ -1443,7 +1444,7 @@ simple_heap_delete(Relation relation, ItemPointer tid)
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result = heap_delete(relation, tid,
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&ctid,
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GetCurrentCommandId(), SnapshotAny,
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GetCurrentCommandId(), InvalidSnapshot,
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true /* wait for commit */ );
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switch (result)
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{
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@ -1477,7 +1478,7 @@ simple_heap_delete(Relation relation, ItemPointer tid)
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* newtup - newly constructed tuple data to store
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* ctid - output parameter, used only for failure case (see below)
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* cid - update command ID to use in verifying old tuple visibility
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* crosscheck - if not SnapshotAny, also check old tuple against this
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* crosscheck - if not InvalidSnapshot, also check old tuple against this
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* wait - true if should wait for any conflicting update to commit/abort
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*
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* Normal, successful return value is HeapTupleMayBeUpdated, which
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@ -1491,7 +1492,8 @@ simple_heap_delete(Relation relation, ItemPointer tid)
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*/
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int
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heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
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ItemPointer ctid, CommandId cid, Snapshot crosscheck, bool wait)
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ItemPointer ctid, CommandId cid,
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Snapshot crosscheck, bool wait)
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{
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ItemId lp;
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HeapTupleData oldtup;
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@ -1566,7 +1568,7 @@ l2:
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result = HeapTupleUpdated;
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}
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if (crosscheck != SnapshotAny && result == HeapTupleMayBeUpdated)
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if (crosscheck != InvalidSnapshot && result == HeapTupleMayBeUpdated)
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{
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/* Perform additional check for serializable RI updates */
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if (!HeapTupleSatisfiesSnapshot(oldtup.t_data, crosscheck))
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@ -1804,7 +1806,7 @@ simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
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result = heap_update(relation, otid, tup,
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&ctid,
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GetCurrentCommandId(), SnapshotAny,
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GetCurrentCommandId(), InvalidSnapshot,
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true /* wait for commit */ );
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switch (result)
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{
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.116 2004/09/06 23:32:54 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.117 2004/09/11 18:28:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -544,7 +544,7 @@ AtCommit_Notify(void)
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*/
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result = heap_update(lRel, &lTuple->t_self, rTuple,
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&ctid,
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GetCurrentCommandId(), SnapshotAny,
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GetCurrentCommandId(), InvalidSnapshot,
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false /* no wait for commit */ );
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switch (result)
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{
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@ -26,7 +26,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.236 2004/08/29 05:06:42 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.237 2004/09/11 18:28:34 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -176,7 +176,7 @@ ExecutorStart(QueryDesc *queryDesc, bool useCurrentSnapshot, bool explainOnly)
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{
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/* normal query --- use query snapshot, no crosscheck */
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estate->es_snapshot = CopyQuerySnapshot();
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estate->es_crosscheck_snapshot = SnapshotAny;
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estate->es_crosscheck_snapshot = InvalidSnapshot;
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}
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/*
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.114 2004/08/29 05:06:42 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.115 2004/09/11 18:28:34 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -179,7 +179,7 @@ CreateExecutorState(void)
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*/
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estate->es_direction = ForwardScanDirection;
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estate->es_snapshot = SnapshotNow;
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estate->es_crosscheck_snapshot = SnapshotAny; /* means no crosscheck */
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estate->es_crosscheck_snapshot = InvalidSnapshot; /* no crosscheck */
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estate->es_range_table = NIL;
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estate->es_result_relations = NULL;
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/tqual.h,v 1.50 2004/08/29 04:13:11 momjian Exp $
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* $PostgreSQL: pgsql/src/include/utils/tqual.h,v 1.51 2004/09/11 18:28:34 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -19,6 +19,20 @@
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#include "access/xact.h"
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/*
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* "Regular" snapshots are pointers to a SnapshotData structure.
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*
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* We also have some "special" snapshot values that have fixed meanings
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* and don't need any backing SnapshotData. These are encoded by small
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* integer values, which of course is a gross violation of ANSI C, but
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* it works fine on all known platforms.
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*
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* SnapshotDirty is an even more special case: its semantics are fixed,
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* but there is a backing SnapshotData struct for it. That struct is
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* actually used as *output* data from tqual.c, not input into it.
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* (But hey, SnapshotDirty ought to have a dirty implementation, no? ;-))
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*/
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typedef struct SnapshotData
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{
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TransactionId xmin; /* XID < xmin are visible to me */
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@ -32,10 +46,12 @@ typedef struct SnapshotData
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typedef SnapshotData *Snapshot;
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#define SnapshotNow ((Snapshot) 0x0)
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#define SnapshotSelf ((Snapshot) 0x1)
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#define SnapshotAny ((Snapshot) 0x2)
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#define SnapshotToast ((Snapshot) 0x3)
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/* Special snapshot values: */
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#define InvalidSnapshot ((Snapshot) 0x0) /* same as NULL */
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#define SnapshotNow ((Snapshot) 0x1)
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#define SnapshotSelf ((Snapshot) 0x2)
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#define SnapshotAny ((Snapshot) 0x3)
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#define SnapshotToast ((Snapshot) 0x4)
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extern DLLIMPORT Snapshot SnapshotDirty;
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extern DLLIMPORT Snapshot QuerySnapshot;
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