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/*-------------------------------------------------------------------------
*
* ginbulk.c
* routines for fast build of inverted index
*
*
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginbulk.c,v 1.19 2010/02/26 02:00:33 momjian Exp $
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/gin.h"
#include "utils/datum.h"
#include "utils/memutils.h"
#define DEF_NENTRY 2048
#define DEF_NPTR 4
static void *
ginAppendData(void *old, void *new, void *arg)
{
EntryAccumulator *eo = (EntryAccumulator *) old,
*en = (EntryAccumulator *) new;
BuildAccumulator *accum = (BuildAccumulator *) arg;
if (eo->number >= eo->length)
{
accum->allocatedMemory -= GetMemoryChunkSpace(eo->list);
eo->length *= 2;
eo->list = (ItemPointerData *) repalloc(eo->list,
sizeof(ItemPointerData) * eo->length);
accum->allocatedMemory += GetMemoryChunkSpace(eo->list);
}
/* If item pointers are not ordered, they will need to be sorted. */
if (eo->shouldSort == FALSE)
{
int res;
res = compareItemPointers(eo->list + eo->number - 1, en->list);
Assert(res != 0);
if (res > 0)
eo->shouldSort = TRUE;
}
eo->list[eo->number] = en->list[0];
eo->number++;
return old;
}
static int
cmpEntryAccumulator(const void *a, const void *b, void *arg)
{
EntryAccumulator *ea = (EntryAccumulator *) a;
EntryAccumulator *eb = (EntryAccumulator *) b;
BuildAccumulator *accum = (BuildAccumulator *) arg;
return compareAttEntries(accum->ginstate, ea->attnum, ea->value,
eb->attnum, eb->value);
}
void
ginInitBA(BuildAccumulator *accum)
{
accum->allocatedMemory = 0;
accum->entryallocator = NULL;
accum->tree = rb_create(cmpEntryAccumulator, ginAppendData, NULL, accum);
accum->iterator = NULL;
accum->tmpList = NULL;
}
/*
* This is basically the same as datumCopy(), but modified to count
* palloc'd space in accum.
*/
static Datum
getDatumCopy(BuildAccumulator *accum, OffsetNumber attnum, Datum value)
{
Form_pg_attribute att = accum->ginstate->origTupdesc->attrs[attnum - 1];
Datum res;
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
ginInsertEntry(BuildAccumulator *accum, ItemPointer heapptr, OffsetNumber attnum, Datum entry)
{
EntryAccumulator *key,
*ea;
/*
* Allocate memory by rather big chunk to decrease overhead, we don't keep
* pointer to previously allocated chunks because they will free by
* MemoryContextReset() call.
*/
if (accum->entryallocator == NULL || accum->length >= DEF_NENTRY)
{
accum->entryallocator = palloc(sizeof(EntryAccumulator) * DEF_NENTRY);
accum->allocatedMemory += GetMemoryChunkSpace(accum->entryallocator);
accum->length = 0;
}
/* "Allocate" new key in chunk */
key = accum->entryallocator + accum->length;
accum->length++;
key->attnum = attnum;
key->value = entry;
/* To prevent multiple palloc/pfree cycles, we reuse array */
if (accum->tmpList == NULL)
accum->tmpList =
(ItemPointerData *) palloc(sizeof(ItemPointerData) * DEF_NPTR);
key->list = accum->tmpList;
key->list[0] = *heapptr;
ea = rb_insert(accum->tree, key);
if (ea == NULL)
{
/*
* The key has been inserted, so continue initialization.
*/
key->value = getDatumCopy(accum, attnum, entry);
key->length = DEF_NPTR;
key->number = 1;
key->shouldSort = FALSE;
accum->allocatedMemory += GetMemoryChunkSpace(key->list);
accum->tmpList = NULL;
}
else
{
/*
* The key has been appended, so "free" allocated key by decrementing
* chunk's counter.
*/
accum->length--;
}
}
/*
* Insert 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 out virtual array, then
* middles of quarters, etc.
*/
void
ginInsertRecordBA(BuildAccumulator *accum, ItemPointer heapptr, OffsetNumber attnum,
Datum *entries, int32 nentry)
{
uint32 step = nentry;
if (nentry <= 0)
return;
Assert(ItemPointerIsValid(heapptr) && attnum >= FirstOffsetNumber);
/*
* step will contain largest power of 2 and <= nentry
*/
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 < nentry && i >= 0; i += step << 1 /* *2 */ )
ginInsertEntry(accum, heapptr, attnum, entries[i]);
step >>= 1; /* /2 */
}
}
static int
qsortCompareItemPointers(const void *a, const void *b)
{
int res = compareItemPointers((ItemPointer) a, (ItemPointer) b);
Assert(res != 0);
return res;
}
ItemPointerData *
ginGetEntry(BuildAccumulator *accum, OffsetNumber *attnum, Datum *value, uint32 *n)
{
EntryAccumulator *entry;
ItemPointerData *list;
if (accum->iterator == NULL)
accum->iterator = rb_begin_iterate(accum->tree, LeftRightWalk);
entry = rb_iterate(accum->iterator);
if (entry == NULL)
return NULL;
*n = entry->number;
*attnum = entry->attnum;
*value = entry->value;
list = entry->list;
Assert(list != NULL);
if (entry->shouldSort && entry->number > 1)
qsort(list, *n, sizeof(ItemPointerData), qsortCompareItemPointers);
return list;
}
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