1 files changed, 293 insertions, 0 deletions
diff --git a/src/backend/access/gin/ginbulk.c b/src/backend/access/gin/ginbulk.c
new file mode 100644
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+++ b/src/backend/access/gin/ginbulk.c
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+/*-------------------------------------------------------------------------
+ *
+ * ginbulk.c
+ *	  routines for fast build of inverted index
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *			src/backend/access/gin/ginbulk.c
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <limits.h>
+
+#include "access/gin_private.h"
+#include "utils/datum.h"
+#include "utils/memutils.h"
+
+
+#define DEF_NENTRY	2048		/* GinEntryAccumulator allocation quantum */
+#define DEF_NPTR	5			/* ItemPointer initial allocation quantum */
+
+
+/* Combiner function for rbtree.c */
+static void
+ginCombineData(RBTNode *existing, const RBTNode *newdata, void *arg)
+{
+	GinEntryAccumulator *eo = (GinEntryAccumulator *) existing;
+	const GinEntryAccumulator *en = (const GinEntryAccumulator *) newdata;
+	BuildAccumulator *accum = (BuildAccumulator *) arg;
+
+	/*
+	 * Note this code assumes that newdata contains only one itempointer.
+	 */
+	if (eo->count >= eo->maxcount)
+	{
+		if (eo->maxcount > INT_MAX)
+			ereport(ERROR,
+					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+					 errmsg("posting list is too long"),
+					 errhint("Reduce maintenance_work_mem.")));
+
+		accum->allocatedMemory -= GetMemoryChunkSpace(eo->list);
+		eo->maxcount *= 2;
+		eo->list = (ItemPointerData *)
+			repalloc_huge(eo->list, sizeof(ItemPointerData) * eo->maxcount);
+		accum->allocatedMemory += GetMemoryChunkSpace(eo->list);
+	}
+
+	/* If item pointers are not ordered, they will need to be sorted later */
+	if (eo->shouldSort == false)
+	{
+		int			res;
+
+		res = ginCompareItemPointers(eo->list + eo->count - 1, en->list);
+		Assert(res != 0);
+
+		if (res > 0)
+			eo->shouldSort = true;
+	}
+
+	eo->list[eo->count] = en->list[0];
+	eo->count++;
+}
+
+/* Comparator function for rbtree.c */
+static int
+cmpEntryAccumulator(const RBTNode *a, const RBTNode *b, void *arg)
+{
+	const GinEntryAccumulator *ea = (const GinEntryAccumulator *) a;
+	const GinEntryAccumulator *eb = (const GinEntryAccumulator *) b;
+	BuildAccumulator *accum = (BuildAccumulator *) arg;
+
+	return ginCompareAttEntries(accum->ginstate,
+								ea->attnum, ea->key, ea->category,
+								eb->attnum, eb->key, eb->category);
+}
+
+/* Allocator function for rbtree.c */
+static RBTNode *
+ginAllocEntryAccumulator(void *arg)
+{
+	BuildAccumulator *accum = (BuildAccumulator *) arg;
+	GinEntryAccumulator *ea;
+
+	/*
+	 * Allocate memory by rather big chunks to decrease overhead.  We have no
+	 * need to reclaim RBTNodes individually, so this costs nothing.
+	 */
+	if (accum->entryallocator == NULL || accum->eas_used >= DEF_NENTRY)
+	{
+		accum->entryallocator = palloc(sizeof(GinEntryAccumulator) * DEF_NENTRY);
+		accum->allocatedMemory += GetMemoryChunkSpace(accum->entryallocator);
+		accum->eas_used = 0;
+	}
+
+	/* Allocate new RBTNode from current chunk */
+	ea = accum->entryallocator + accum->eas_used;
+	accum->eas_used++;
+
+	return (RBTNode *) ea;
+}
+
+void
+ginInitBA(BuildAccumulator *accum)
+{
+	/* accum->ginstate is intentionally not set here */
+	accum->allocatedMemory = 0;
+	accum->entryallocator = NULL;
+	accum->eas_used = 0;
+	accum->tree = rbt_create(sizeof(GinEntryAccumulator),
+							 cmpEntryAccumulator,
+							 ginCombineData,
+							 ginAllocEntryAccumulator,
+							 NULL,	/* no freefunc needed */
+							 (void *) accum);
+}
+
+/*
+ * This is basically the same as datumCopy(), but extended to count
+ * palloc'd space in accum->allocatedMemory.
+ */
+static Datum
+getDatumCopy(BuildAccumulator *accum, OffsetNumber attnum, Datum value)
+{
+	Form_pg_attribute att;
+	Datum		res;
+
+	att = TupleDescAttr(accum->ginstate->origTupdesc, attnum - 1);
+	if (att->attbyval)
+		res = value;
+	else
+	{
+		res = datumCopy(value, false, att->attlen);
+		accum->allocatedMemory += GetMemoryChunkSpace(DatumGetPointer(res));
+	}
+	return res;
+}
+
+/*
+ * Find/store one entry from indexed value.
+ */
+static void
+ginInsertBAEntry(BuildAccumulator *accum,
+				 ItemPointer heapptr, OffsetNumber attnum,
+				 Datum key, GinNullCategory category)
+{
+	GinEntryAccumulator eatmp;
+	GinEntryAccumulator *ea;
+	bool		isNew;
+
+	/*
+	 * For the moment, fill only the fields of eatmp that will be looked at by
+	 * cmpEntryAccumulator or ginCombineData.
+	 */
+	eatmp.attnum = attnum;
+	eatmp.key = key;
+	eatmp.category = category;
+	/* temporarily set up single-entry itempointer list */
+	eatmp.list = heapptr;
+
+	ea = (GinEntryAccumulator *) rbt_insert(accum->tree, (RBTNode *) &eatmp,
+											&isNew);
+
+	if (isNew)
+	{
+		/*
+		 * Finish initializing new tree entry, including making permanent
+		 * copies of the datum (if it's not null) and itempointer.
+		 */
+		if (category == GIN_CAT_NORM_KEY)
+			ea->key = getDatumCopy(accum, attnum, key);
+		ea->maxcount = DEF_NPTR;
+		ea->count = 1;
+		ea->shouldSort = false;
+		ea->list =
+			(ItemPointerData *) palloc(sizeof(ItemPointerData) * DEF_NPTR);
+		ea->list[0] = *heapptr;
+		accum->allocatedMemory += GetMemoryChunkSpace(ea->list);
+	}
+	else
+	{
+		/*
+		 * ginCombineData did everything needed.
+		 */
+	}
+}
+
+/*
+ * Insert the entries for one heap pointer.
+ *
+ * Since the entries are being inserted into a balanced binary tree, you
+ * might think that the order of insertion wouldn't be critical, but it turns
+ * out that inserting the entries in sorted order results in a lot of
+ * rebalancing operations and is slow.  To prevent this, we attempt to insert
+ * the nodes in an order that will produce a nearly-balanced tree if the input
+ * is in fact sorted.
+ *
+ * We do this as follows.  First, we imagine that we have an array whose size
+ * is the smallest power of two greater than or equal to the actual array
+ * size.  Second, we insert the middle entry of our virtual array into the
+ * tree; then, we insert the middles of each half of our virtual array, then
+ * middles of quarters, etc.
+ */
+void
+ginInsertBAEntries(BuildAccumulator *accum,
+				   ItemPointer heapptr, OffsetNumber attnum,
+				   Datum *entries, GinNullCategory *categories,
+				   int32 nentries)
+{
+	uint32		step = nentries;
+
+	if (nentries <= 0)
+		return;
+
+	Assert(ItemPointerIsValid(heapptr) && attnum >= FirstOffsetNumber);
+
+	/*
+	 * step will contain largest power of 2 and <= nentries
+	 */
+	step |= (step >> 1);
+	step |= (step >> 2);
+	step |= (step >> 4);
+	step |= (step >> 8);
+	step |= (step >> 16);
+	step >>= 1;
+	step++;
+
+	while (step > 0)
+	{
+		int			i;
+
+		for (i = step - 1; i < nentries && i >= 0; i += step << 1 /* *2 */ )
+			ginInsertBAEntry(accum, heapptr, attnum,
+							 entries[i], categories[i]);
+
+		step >>= 1;				/* /2 */
+	}
+}
+
+static int
+qsortCompareItemPointers(const void *a, const void *b)
+{
+	int			res = ginCompareItemPointers((ItemPointer) a, (ItemPointer) b);
+
+	/* Assert that there are no equal item pointers being sorted */
+	Assert(res != 0);
+	return res;
+}
+
+/* Prepare to read out the rbtree contents using ginGetBAEntry */
+void
+ginBeginBAScan(BuildAccumulator *accum)
+{
+	rbt_begin_iterate(accum->tree, LeftRightWalk, &accum->tree_walk);
+}
+
+/*
+ * Get the next entry in sequence from the BuildAccumulator's rbtree.
+ * This consists of a single key datum and a list (array) of one or more
+ * heap TIDs in which that key is found.  The list is guaranteed sorted.
+ */
+ItemPointerData *
+ginGetBAEntry(BuildAccumulator *accum,
+			  OffsetNumber *attnum, Datum *key, GinNullCategory *category,
+			  uint32 *n)
+{
+	GinEntryAccumulator *entry;
+	ItemPointerData *list;
+
+	entry = (GinEntryAccumulator *) rbt_iterate(&accum->tree_walk);
+
+	if (entry == NULL)
+		return NULL;			/* no more entries */
+
+	*attnum = entry->attnum;
+	*key = entry->key;
+	*category = entry->category;
+	list = entry->list;
+	*n = entry->count;
+
+	Assert(list != NULL && entry->count > 0);
+
+	if (entry->shouldSort && entry->count > 1)
+		qsort(list, entry->count, sizeof(ItemPointerData),
+			  qsortCompareItemPointers);
+
+	return list;
+}