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Fix nasty TRUNCATE bug reported by Darrin Ladd. RelationTruncateIndexes

would close and then re-open rel being truncated. Depending on theluck of the draw, the re-opened relcache entry might or might not beat the same physical location as before. Unfortunately, if it wasn'tthen heap_truncate would crash and burn, because it still had a pointerat the old location. Fix is to open and then close rel inRelationTruncateIndexes, so that rel's refcount never goes to zerountil heap_truncate is done.

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src/backend/catalog
- heap.c

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+24

-28

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`‎src/backend/catalog/heap.c‎`

Lines changed: 24 additions & 28 deletions

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.145 2000/09/29 18:21:25 tgl Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.146 2000/09/30 18:28:53 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*`
`14`	`14`	`* INTERFACE ROUTINES`
`@@ -1064,32 +1064,32 @@ DeleteRelationTuple(Relation rel)`
`1064`	`1064`	`* RelationTruncateIndexes - This routine is used to truncate all`
`1065`	`1065`	`* indices associated with the heap relation to zero tuples.`
`1066`	`1066`	`* The routine will truncate and then reconstruct the indices on`
`1067`		`- * the relation specified by theheapRelation parameter.`
	`1067`	`+ * the relation specified by theheapId parameter.`
`1068`	`1068`	`* --------------------------------`
`1069`	`1069`	`*/`
`1070`	`1070`	`staticvoid`
`1071`		`-RelationTruncateIndexes(RelationheapRelation)`
	`1071`	`+RelationTruncateIndexes(OidheapId)`
`1072`	`1072`	`{`
`1073`		`-RelationindexRelation,`
`1074`		`-currentIndex;`
	`1073`	`+RelationindexRelation;`
`1075`	`1074`	`ScanKeyDataentry;`
`1076`	`1075`	`HeapScanDescscan;`
`1077`		`-HeapTupleindexTuple,`
`1078`		`-classTuple;`
`1079`		`-IndexInfo*indexInfo;`
`1080`		`-OidheapId,`
`1081`		`-indexId,`
`1082`		`-accessMethodId;`
`1083`		`-`
`1084`		`-heapId=RelationGetRelid(heapRelation);`
	`1076`	`+HeapTupleindexTuple;`
`1085`	`1077`
`1086`		`-/* Scan pg_index to find indexes onheapRelation */`
	`1078`	`+/* Scan pg_index to find indexes onspecified heap */`
`1087`	`1079`	`indexRelation=heap_openr(IndexRelationName,AccessShareLock);`
`1088`	`1080`	`ScanKeyEntryInitialize(&entry,0,Anum_pg_index_indrelid,F_OIDEQ,`
`1089`	`1081`	`ObjectIdGetDatum(heapId));`
`1090`	`1082`	`scan=heap_beginscan(indexRelation, false,SnapshotNow,1,&entry);`
	`1083`	`+`
`1091`	`1084`	`while (HeapTupleIsValid(indexTuple=heap_getnext(scan,0)))`
`1092`	`1085`	`{`
	`1086`	`+OidindexId,`
	`1087`	`+accessMethodId;`
	`1088`	`+IndexInfo*indexInfo;`
	`1089`	`+HeapTupleclassTuple;`
	`1090`	`+RelationheapRelation,`
	`1091`	`+currentIndex;`
	`1092`	`+`
`1093`	`1093`	`/*`
`1094`	`1094`	`* For each index, fetch info needed for index_build`
`1095`	`1095`	`*/`
`@@ -1105,10 +1105,16 @@ RelationTruncateIndexes(Relation heapRelation)`
`1105`	`1105`	`indexId);`
`1106`	`1106`	`accessMethodId= ((Form_pg_class)GETSTRUCT(classTuple))->relam;`
`1107`	`1107`
	`1108`	`+/*`
	`1109`	`+ * We have to re-open the heap rel each time through this loop`
	`1110`	`+ * because index_build will close it again. We need grab no lock,`
	`1111`	`+ * however, because we assume heap_truncate is holding an exclusive`
	`1112`	`+ * lock on the heap rel.`
	`1113`	`+ */`
	`1114`	`+heapRelation=heap_open(heapId,NoLock);`
	`1115`	`+`
`1108`	`1116`	`/* Open the index relation */`
`1109`	`1117`	`currentIndex=index_open(indexId);`
`1110`		`-if (currentIndex==NULL)`
`1111`		`-elog(ERROR,"RelationTruncateIndexes: can't open index relation");`
`1112`	`1118`
`1113`	`1119`	`/* Obtain exclusive lock on it, just to be sure */`
`1114`	`1120`	`LockRelation(currentIndex,AccessExclusiveLock);`
`@@ -1127,15 +1133,10 @@ RelationTruncateIndexes(Relation heapRelation)`
`1127`	`1133`	`InitIndexStrategy(indexInfo->ii_NumIndexAttrs,`
`1128`	`1134`	`currentIndex,accessMethodId);`
`1129`	`1135`	`index_build(heapRelation,currentIndex,indexInfo,NULL);`
`1130`		`-`
`1131`	`1136`	`/*`
`1132`	`1137`	`* index_build will close both the heap and index relations (but`
`1133`		`- * not give up the locks we hold on them).That's fine for the`
`1134`		`- * index, but we need to open the heap again. We need no new`
`1135`		`- * lock, since this backend still has the exclusive lock grabbed`
`1136`		`- * by heap_truncate.`
	`1138`	`+ * not give up the locks we hold on them).`
`1137`	`1139`	`*/`
`1138`		`-heapRelation=heap_open(heapId,NoLock);`
`1139`	`1140`	`}`
`1140`	`1141`
`1141`	`1142`	`/* Complete the scan and close pg_index */`
`@@ -1191,17 +1192,12 @@ heap_truncate(char *relname)`
`1191`	`1192`	`rel->rd_nblocks=0;`
`1192`	`1193`
`1193`	`1194`	`/* If this relation has indexes, truncate the indexes too */`
`1194`		`-RelationTruncateIndexes(rel);`
	`1195`	`+RelationTruncateIndexes(rid);`
`1195`	`1196`
`1196`	`1197`	`/*`
`1197`	`1198`	`* Close the relation, but keep exclusive lock on it until commit.`
`1198`	`1199`	`*/`
`1199`	`1200`	`heap_close(rel,NoLock);`
`1200`		`-`
`1201`		`-/*`
`1202`		`- * Is this really necessary?`
`1203`		`- */`
`1204`		`-RelationForgetRelation(rid);`
`1205`	`1201`	`}`
`1206`	`1202`
`1207`	`1203`

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`‎src/backend/catalog/heap.c‎`

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