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HashAgg: release write buffers sooner by rewinding tape.
This was an oversight. The purpose of 7fdd919ae7
was to avoid keeping
tape buffers around unnecessisarily, but HashAgg didn't rewind early
enough.
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/1fb1151c2cddf8747d14e0532da283c3f97e2685.camel@j-davis.com
Backpatch-through: 13
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@ -2639,8 +2639,6 @@ agg_refill_hash_table(AggState *aggstate)
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*/
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hashagg_recompile_expressions(aggstate, true, true);
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LogicalTapeRewindForRead(tapeinfo->tapeset, batch->input_tapenum,
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HASHAGG_READ_BUFFER_SIZE);
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for (;;)
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{
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TupleTableSlot *spillslot = aggstate->hash_spill_rslot;
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@ -2923,6 +2921,7 @@ hashagg_tapeinfo_assign(HashTapeInfo *tapeinfo, int *partitions,
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static void
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hashagg_tapeinfo_release(HashTapeInfo *tapeinfo, int tapenum)
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{
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/* rewinding frees the buffer while not in use */
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LogicalTapeRewindForWrite(tapeinfo->tapeset, tapenum);
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if (tapeinfo->freetapes_alloc == tapeinfo->nfreetapes)
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{
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@ -3152,6 +3151,7 @@ hashagg_spill_finish(AggState *aggstate, HashAggSpill *spill, int setno)
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for (i = 0; i < spill->npartitions; i++)
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{
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LogicalTapeSet *tapeset = aggstate->hash_tapeinfo->tapeset;
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int tapenum = spill->partitions[i];
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HashAggBatch *new_batch;
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double cardinality;
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@ -3163,9 +3163,13 @@ hashagg_spill_finish(AggState *aggstate, HashAggSpill *spill, int setno)
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cardinality = estimateHyperLogLog(&spill->hll_card[i]);
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freeHyperLogLog(&spill->hll_card[i]);
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new_batch = hashagg_batch_new(aggstate->hash_tapeinfo->tapeset,
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tapenum, setno, spill->ntuples[i],
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cardinality, used_bits);
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/* rewinding frees the buffer while not in use */
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LogicalTapeRewindForRead(tapeset, tapenum,
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HASHAGG_READ_BUFFER_SIZE);
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new_batch = hashagg_batch_new(tapeset, tapenum, setno,
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spill->ntuples[i], cardinality,
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used_bits);
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aggstate->hash_batches = lcons(new_batch, aggstate->hash_batches);
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aggstate->hash_batches_used++;
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}
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