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Commit2647b24

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Fix possible "invalid memory alloc request size" failure in nodeHash.c.
Limit the size of the hashtable pointer array to not more thanMaxAllocSize. We've seen reports of failures due to this in HEAD/9.5,and it seems possible in older branches as well. The change inNTUP_PER_BUCKET in 9.5 may have made the problem more likely, butsurely it didn't introduce it.Tomas Vondra, slightly modified by me
1 parent47ac95f commit2647b24

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‎src/backend/executor/nodeHash.c

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -459,10 +459,12 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
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* Set nbuckets to achieve an average bucket load of NTUP_PER_BUCKET when
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* memory is filled. Set nbatch to the smallest power of 2 that appears
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* sufficient. The Min() steps limit the results so that the pointer
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* arrays we'll try to allocate do not exceed work_mem.
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* arrays we'll try to allocate do not exceed work_mem nor MaxAllocSize.
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*/
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max_pointers= (work_mem*1024L) /sizeof(void*);
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max_pointers= (work_mem*1024L) /sizeof(HashJoinTuple);
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max_pointers=Min(max_pointers,MaxAllocSize /sizeof(HashJoinTuple));
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/* also ensure we avoid integer overflow in nbatch and nbuckets */
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/* (this step is redundant given the current value of MaxAllocSize) */
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max_pointers=Min(max_pointers,INT_MAX /2);
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if (inner_rel_bytes>hash_table_bytes)

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