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-rw-r--r--contrib/bloom/blscan.c172
1 files changed, 172 insertions, 0 deletions
diff --git a/contrib/bloom/blscan.c b/contrib/bloom/blscan.c
new file mode 100644
index 0000000..3c71401
--- /dev/null
+++ b/contrib/bloom/blscan.c
@@ -0,0 +1,172 @@
+/*-------------------------------------------------------------------------
+ *
+ * blscan.c
+ * Bloom index scan functions.
+ *
+ * Copyright (c) 2016-2020, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * contrib/bloom/blscan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/relscan.h"
+#include "bloom.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "storage/bufmgr.h"
+#include "storage/lmgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+
+/*
+ * Begin scan of bloom index.
+ */
+IndexScanDesc
+blbeginscan(Relation r, int nkeys, int norderbys)
+{
+ IndexScanDesc scan;
+ BloomScanOpaque so;
+
+ scan = RelationGetIndexScan(r, nkeys, norderbys);
+
+ so = (BloomScanOpaque) palloc(sizeof(BloomScanOpaqueData));
+ initBloomState(&so->state, scan->indexRelation);
+ so->sign = NULL;
+
+ scan->opaque = so;
+
+ return scan;
+}
+
+/*
+ * Rescan a bloom index.
+ */
+void
+blrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
+ ScanKey orderbys, int norderbys)
+{
+ BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
+
+ if (so->sign)
+ pfree(so->sign);
+ so->sign = NULL;
+
+ if (scankey && scan->numberOfKeys > 0)
+ {
+ memmove(scan->keyData, scankey,
+ scan->numberOfKeys * sizeof(ScanKeyData));
+ }
+}
+
+/*
+ * End scan of bloom index.
+ */
+void
+blendscan(IndexScanDesc scan)
+{
+ BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
+
+ if (so->sign)
+ pfree(so->sign);
+ so->sign = NULL;
+}
+
+/*
+ * Insert all matching tuples into a bitmap.
+ */
+int64
+blgetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
+{
+ int64 ntids = 0;
+ BlockNumber blkno = BLOOM_HEAD_BLKNO,
+ npages;
+ int i;
+ BufferAccessStrategy bas;
+ BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
+
+ if (so->sign == NULL)
+ {
+ /* New search: have to calculate search signature */
+ ScanKey skey = scan->keyData;
+
+ so->sign = palloc0(sizeof(BloomSignatureWord) * so->state.opts.bloomLength);
+
+ for (i = 0; i < scan->numberOfKeys; i++)
+ {
+ /*
+ * Assume bloom-indexable operators to be strict, so nothing could
+ * be found for NULL key.
+ */
+ if (skey->sk_flags & SK_ISNULL)
+ {
+ pfree(so->sign);
+ so->sign = NULL;
+ return 0;
+ }
+
+ /* Add next value to the signature */
+ signValue(&so->state, so->sign, skey->sk_argument,
+ skey->sk_attno - 1);
+
+ skey++;
+ }
+ }
+
+ /*
+ * We're going to read the whole index. This is why we use appropriate
+ * buffer access strategy.
+ */
+ bas = GetAccessStrategy(BAS_BULKREAD);
+ npages = RelationGetNumberOfBlocks(scan->indexRelation);
+
+ for (blkno = BLOOM_HEAD_BLKNO; blkno < npages; blkno++)
+ {
+ Buffer buffer;
+ Page page;
+
+ buffer = ReadBufferExtended(scan->indexRelation, MAIN_FORKNUM,
+ blkno, RBM_NORMAL, bas);
+
+ LockBuffer(buffer, BUFFER_LOCK_SHARE);
+ page = BufferGetPage(buffer);
+ TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page);
+
+ if (!PageIsNew(page) && !BloomPageIsDeleted(page))
+ {
+ OffsetNumber offset,
+ maxOffset = BloomPageGetMaxOffset(page);
+
+ for (offset = 1; offset <= maxOffset; offset++)
+ {
+ BloomTuple *itup = BloomPageGetTuple(&so->state, page, offset);
+ bool res = true;
+
+ /* Check index signature with scan signature */
+ for (i = 0; i < so->state.opts.bloomLength; i++)
+ {
+ if ((itup->sign[i] & so->sign[i]) != so->sign[i])
+ {
+ res = false;
+ break;
+ }
+ }
+
+ /* Add matching tuples to bitmap */
+ if (res)
+ {
+ tbm_add_tuples(tbm, &itup->heapPtr, 1, true);
+ ntids++;
+ }
+ }
+ }
+
+ UnlockReleaseBuffer(buffer);
+ CHECK_FOR_INTERRUPTS();
+ }
+ FreeAccessStrategy(bas);
+
+ return ntids;
+}