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Commit8a3f745

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Do not access indclass through Form_pg_index
Normally, accessing variable-length members of catalog structures pastthe first one doesn't work at all. Here, it happened to work becauseindnatts was checked to be 1, and so the defined FormData_pg_indexlayout, using int2vector[1] and oidvector[1] for variable-lengtharrays, happened to match the actual memory layout. But it's a veryfragile assumption, and it's not in a performance-critical path, socode it properly using heap_getattr() instead.bug analysis by Tom Lane
1 parenteb6af01 commit8a3f745

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‎src/backend/utils/cache/relcache.c

Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3351,15 +3351,30 @@ RelationGetIndexList(Relation relation)
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while (HeapTupleIsValid(htup=systable_getnext(indscan)))
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{
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Form_pg_indexindex= (Form_pg_index)GETSTRUCT(htup);
3354+
DatumindclassDatum;
3355+
oidvector*indclass;
3356+
boolisnull;
33543357

33553358
/* Add index's OID to result list in the proper order */
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result=insert_ordered_oid(result,index->indexrelid);
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3361+
/*
3362+
* indclass cannot be referenced directly through the C struct, because
3363+
* it comes after the variable-width indkey field. Must extract the
3364+
* datum the hard way...
3365+
*/
3366+
indclassDatum=heap_getattr(htup,
3367+
Anum_pg_index_indclass,
3368+
GetPgIndexDescriptor(),
3369+
&isnull);
3370+
Assert(!isnull);
3371+
indclass= (oidvector*)DatumGetPointer(indclassDatum);
3372+
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/* Check to see if it is a unique, non-partial btree index on OID */
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if (index->indnatts==1&&
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index->indisunique&&index->indimmediate&&
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index->indkey.values[0]==ObjectIdAttributeNumber&&
3362-
index->indclass.values[0]==OID_BTREE_OPS_OID&&
3377+
indclass->values[0]==OID_BTREE_OPS_OID&&
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heap_attisnull(htup,Anum_pg_index_indpred))
33643379
oidIndex=index->indexrelid;
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}

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