From eca2e158957fe86fd32927cc3752db9868c4d957 Mon Sep 17 00:00:00 2001 From: Antonin Houska Date: Tue, 16 Jun 2026 13:54:16 +0200 Subject: [PATCH 1/8] Use tuple slot to pass tuples for rewriting. This patch tries to adopt the preferable way of handling tuples, i.e. pass the containing tuple slot rather than the actual tuple. The motivation is that heap_insert_for_repack() will need a slot in the near future, in order to call ExecInsertIndexTuples(). Also, in order to set values of dropped attributes to to NULL, it seems more compact to pass a tuple slot as a workspace than two arrays (one for values and one for nulls). --- src/backend/access/heap/heapam_handler.c | 199 +++++++++++++---------- 1 file changed, 110 insertions(+), 89 deletions(-) diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 2268cc277bc..127d4415084 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -48,14 +48,13 @@ #include "utils/rel.h" #include "utils/tuplesort.h" -static void reform_and_rewrite_tuple(HeapTuple tuple, - Relation OldHeap, Relation NewHeap, - Datum *values, bool *isnull, RewriteState rwstate); -static void heap_insert_for_repack(HeapTuple tuple, Relation OldHeap, - Relation NewHeap, Datum *values, bool *isnull, - BulkInsertState bistate); -static HeapTuple reform_tuple(HeapTuple tuple, Relation OldHeap, - Relation NewHeap, Datum *values, bool *isnull); +static void reform_and_rewrite_tuple(TupleTableSlot *src, TupleTableSlot *reform, + RewriteState rwstate); +static void heap_insert_for_repack(Relation rel, TupleTableSlot *src, + TupleTableSlot *reform, + BulkInsertStateData *bistate); +static bool tuple_needs_reform(HeapTuple tuple, TupleDesc tupDesc); +static void clear_dropped_attributes(HeapTuple tuple, TupleTableSlot *reform); static bool SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer, HeapTuple tuple, @@ -609,11 +608,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, bool is_system_catalog; Tuplesortstate *tuplesort; TupleDesc oldTupDesc = RelationGetDescr(OldHeap); - TupleDesc newTupDesc = RelationGetDescr(NewHeap); TupleTableSlot *slot; - int natts; - Datum *values; - bool *isnull; + TupleTableSlot *reform_slot; BufferHeapTupleTableSlot *hslot; BlockNumber prev_cblock = InvalidBlockNumber; bool concurrent = snapshot != NULL; @@ -627,11 +623,6 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, */ Assert(RelationGetTargetBlock(NewHeap) == InvalidBlockNumber); - /* Preallocate values/isnull arrays */ - natts = newTupDesc->natts; - values = palloc_array(Datum, natts); - isnull = palloc_array(bool, natts); - /* * In non-concurrent mode, initialize the rewrite operation. This is not * needed in concurrent mode. @@ -705,6 +696,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, slot = table_slot_create(OldHeap, NULL); hslot = (BufferHeapTupleTableSlot *) slot; + reform_slot = MakeSingleTupleTableSlot(RelationGetDescr(OldHeap), + &TTSOpsVirtual); /* * Scan through the OldHeap, either in OldIndex order or sequentially; @@ -881,11 +874,9 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, int64 ct_val[2]; if (!concurrent) - reform_and_rewrite_tuple(tuple, OldHeap, NewHeap, - values, isnull, rwstate); + reform_and_rewrite_tuple(slot, reform_slot, rwstate); else - heap_insert_for_repack(tuple, OldHeap, NewHeap, - values, isnull, bistate); + heap_insert_for_repack(NewHeap, slot, reform_slot, bistate); /* * In indexscan mode and also VACUUM FULL, report increase in @@ -901,8 +892,7 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, index_endscan(indexScan); if (tableScan != NULL) table_endscan(tableScan); - if (slot) - ExecDropSingleTupleTableSlot(slot); + ExecDropSingleTupleTableSlot(slot); /* * In scan-and-sort mode, complete the sort, then read out all live tuples @@ -922,6 +912,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, pgstat_progress_update_param(PROGRESS_REPACK_PHASE, PROGRESS_REPACK_PHASE_WRITE_NEW_HEAP); + slot = MakeSingleTupleTableSlot(RelationGetDescr(OldHeap), + &TTSOpsHeapTuple); for (;;) { HeapTuple tuple; @@ -932,33 +924,36 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, if (tuple == NULL) break; + /* + * XXX Ideally we should use tuplesort_gettupleslot() above, but + * it retrieves minimal tuples and tuplesort_puttupleslot() cannot + * get the tuple descriptor from tuplesort created by + * tuplesort_begin_cluster(). + */ + ExecStoreHeapTuple(tuple, slot, false); + n_tuples += 1; if (!concurrent) - reform_and_rewrite_tuple(tuple, - OldHeap, NewHeap, - values, isnull, - rwstate); + reform_and_rewrite_tuple(slot, reform_slot, rwstate); else - heap_insert_for_repack(tuple, OldHeap, NewHeap, - values, isnull, bistate); + heap_insert_for_repack(NewHeap, slot, reform_slot, bistate); /* Report n_tuples */ pgstat_progress_update_param(PROGRESS_REPACK_HEAP_TUPLES_INSERTED, n_tuples); } + ExecDropSingleTupleTableSlot(slot); tuplesort_end(tuplesort); } + ExecDropSingleTupleTableSlot(reform_slot); + /* Write out any remaining tuples, and fsync if needed */ if (rwstate) end_heap_rewrite(rwstate); if (bistate) FreeBulkInsertState(bistate); - - /* Clean up */ - pfree(values); - pfree(isnull); } /* @@ -2346,21 +2341,45 @@ heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate, * currently only known to happen as an after-effect of ALTER TABLE * SET WITHOUT OIDS. * - * So, we must reconstruct the tuple from component Datums. + * So, we must reconstruct the tuple from component Datums. 'reform' slot + * is a workspace for this reconstruction. */ static void -reform_and_rewrite_tuple(HeapTuple tuple, - Relation OldHeap, Relation NewHeap, - Datum *values, bool *isnull, RewriteState rwstate) +reform_and_rewrite_tuple(TupleTableSlot *src, TupleTableSlot *reform, + RewriteState rwstate) { - HeapTuple newtuple; + HeapTuple tuple, + newtuple; + bool shouldFree, + shouldFreeNew; - newtuple = reform_tuple(tuple, OldHeap, NewHeap, values, isnull); + /* + * The old tuple will not be modified, so do not request materialization. + * (A copy can be created for specific slot type though, e.g. + * TTSOpsMinimalTuple.) + */ + tuple = ExecFetchSlotHeapTuple(src, false, &shouldFree); + if (tuple_needs_reform(tuple, src->tts_tupleDescriptor)) + { + clear_dropped_attributes(tuple, reform); + + /* No need to materialize, copy will be created anyway. */ + Assert(TTS_IS_VIRTUAL(reform)); + newtuple = ExecFetchSlotHeapTuple(reform, false, &shouldFreeNew); + } + else + { + newtuple = heap_copytuple(tuple); + shouldFreeNew = true; + } /* The heap rewrite module does the rest */ rewrite_heap_tuple(rwstate, tuple, newtuple); - heap_freetuple(newtuple); + if (shouldFree) + heap_freetuple(tuple); + if (shouldFreeNew) + heap_freetuple(newtuple); } /* @@ -2372,6 +2391,9 @@ reform_and_rewrite_tuple(HeapTuple tuple, * information). Thus we must use heap_insert() both during the * catch-up and here. * + * 'reform' is a slot to use for tuple "reforming", typically to get set + * values of dropped columns to NULL. + * * We pass the NO_LOGICAL flag to heap_insert() in order to skip logical * decoding: as soon as REPACK CONCURRENTLY swaps the relation files, it drops * this relation, so no logical replication subscription should need the data. @@ -2380,76 +2402,75 @@ reform_and_rewrite_tuple(HeapTuple tuple, * case. */ static void -heap_insert_for_repack(HeapTuple tuple, Relation OldHeap, Relation NewHeap, - Datum *values, bool *isnull, BulkInsertState bistate) +heap_insert_for_repack(Relation rel, TupleTableSlot *src, + TupleTableSlot *reform, BulkInsertStateData *bistate) { - HeapTuple newtuple; + HeapTuple tuple; + bool shouldFree; + TupleTableSlot *slot; - newtuple = reform_tuple(tuple, OldHeap, NewHeap, values, isnull); + tuple = ExecFetchSlotHeapTuple(src, false, &shouldFree); + if (tuple_needs_reform(tuple, src->tts_tupleDescriptor)) + { + clear_dropped_attributes(tuple, reform); + slot = reform; + } + else + slot = src; - heap_insert(NewHeap, newtuple, GetCurrentCommandId(true), - HEAP_INSERT_NO_LOGICAL, bistate); + /* + * clear_dropped_attributes() should have deformed the tuple, so nothing + * should depend on it now. + */ + if (shouldFree) + heap_freetuple(tuple); - heap_freetuple(newtuple); + table_tuple_insert(rel, slot, GetCurrentCommandId(true), + TABLE_INSERT_NO_LOGICAL, bistate); } -/* - * Subroutine for reform_and_rewrite_tuple and heap_insert_for_repack. - * - * Deform the given tuple, set values of dropped columns to NULL, and fill in - * any values from attmissingval; then form a new tuple and return it. If no - * attributes need to be changed, a copy of the original tuple is returned. - * Caller is responsible for freeing the returned tuple. - * - * XXX this coding assumes that both relations have the same tupledesc. - */ -static HeapTuple -reform_tuple(HeapTuple tuple, Relation OldHeap, Relation NewHeap, - Datum *values, bool *isnull) +static bool +tuple_needs_reform(HeapTuple tuple, TupleDesc tupDesc) { - TupleDesc oldTupDesc = RelationGetDescr(OldHeap); - TupleDesc newTupDesc = RelationGetDescr(NewHeap); - bool needs_reform = false; - /* * A short tuple might require values from attmissing val, so activate the * coding unconditionally in that case. The value might legitimally be * NULL otherwise, so this is slightly wasteful, but it probably beats * having to test each attribute for presence of attmissingval each time. */ - if (HeapTupleHeaderGetNatts(tuple->t_data) < newTupDesc->natts) - needs_reform = true; + if (HeapTupleHeaderGetNatts(tuple->t_data) < tupDesc->natts) + return true; - /* - * If the column has been dropped but a value is still present, we can - * optimize storage now by getting rid of it. - */ - if (!needs_reform) + /* Does it have dropped attributes? */ + for (int i = 0; i < tupDesc->natts; i++) { - for (int i = 0; i < newTupDesc->natts; i++) - { - if (TupleDescCompactAttr(newTupDesc, i)->attisdropped && - !heap_attisnull(tuple, i + 1, newTupDesc)) - { - needs_reform = true; - break; - } - } + if (TupleDescCompactAttr(tupDesc, i)->attisdropped && + !heap_attisnull(tuple, i + 1, tupDesc)) + return true; } - /* Skip work if no changes are needed */ - if (!needs_reform) - return heap_copytuple(tuple); + return false; +} - heap_deform_tuple(tuple, oldTupDesc, values, isnull); +/* + * Subroutine for reform_and_rewrite_tuple and heap_insert_for_repack. + * + * Set values of dropped columns to NULL, + */ +static void +clear_dropped_attributes(HeapTuple tuple, TupleTableSlot *reform) +{ + TupleDesc tupDesc = reform->tts_tupleDescriptor; + + /* Assuming 'reform' is virtual, this deforms the tuple. */ + Assert(TTS_IS_VIRTUAL(reform)); + ExecForceStoreHeapTuple(tuple, reform, false); - for (int i = 0; i < newTupDesc->natts; i++) + for (int i = 0; i < tupDesc->natts; i++) { - if (TupleDescCompactAttr(newTupDesc, i)->attisdropped) - isnull[i] = true; + if (TupleDescCompactAttr(tupDesc, i)->attisdropped) + reform->tts_isnull[i] = true; } - - return heap_form_tuple(newTupDesc, values, isnull); } /* -- 2.52.0