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path: root/src/backend/access/nbtree/nbtscan.c
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Diffstat (limited to 'src/backend/access/nbtree/nbtscan.c')
-rw-r--r--src/backend/access/nbtree/nbtscan.c267
1 files changed, 138 insertions, 129 deletions
diff --git a/src/backend/access/nbtree/nbtscan.c b/src/backend/access/nbtree/nbtscan.c
index 5e23fe13d7b..8a2042403ad 100644
--- a/src/backend/access/nbtree/nbtscan.c
+++ b/src/backend/access/nbtree/nbtscan.c
@@ -1,28 +1,28 @@
/*-------------------------------------------------------------------------
*
* btscan.c--
- * manage scans on btrees.
+ * manage scans on btrees.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.7 1997/02/18 17:13:45 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.8 1997/09/07 04:38:57 momjian Exp $
*
*
* NOTES
- * Because we can be doing an index scan on a relation while we update
- * it, we need to avoid missing data that moves around in the index.
- * The routines and global variables in this file guarantee that all
- * scans in the local address space stay correctly positioned. This
- * is all we need to worry about, since write locking guarantees that
- * no one else will be on the same page at the same time as we are.
+ * Because we can be doing an index scan on a relation while we update
+ * it, we need to avoid missing data that moves around in the index.
+ * The routines and global variables in this file guarantee that all
+ * scans in the local address space stay correctly positioned. This
+ * is all we need to worry about, since write locking guarantees that
+ * no one else will be on the same page at the same time as we are.
*
- * The scheme is to manage a list of active scans in the current backend.
- * Whenever we add or remove records from an index, or whenever we
- * split a leaf page, we check the list of active scans to see if any
- * has been affected. A scan is affected only if it is on the same
- * relation, and the same page, as the update.
+ * The scheme is to manage a list of active scans in the current backend.
+ * Whenever we add or remove records from an index, or whenever we
+ * split a leaf page, we check the list of active scans to see if any
+ * has been affected. A scan is affected only if it is on the same
+ * relation, and the same page, as the update.
*
*-------------------------------------------------------------------------
*/
@@ -32,83 +32,87 @@
#include <storage/bufpage.h>
#include <access/nbtree.h>
-typedef struct BTScanListData {
- IndexScanDesc btsl_scan;
- struct BTScanListData *btsl_next;
-} BTScanListData;
+typedef struct BTScanListData
+{
+ IndexScanDesc btsl_scan;
+ struct BTScanListData *btsl_next;
+} BTScanListData;
-typedef BTScanListData *BTScanList;
+typedef BTScanListData *BTScanList;
-static BTScanList BTScans = (BTScanList) NULL;
+static BTScanList BTScans = (BTScanList) NULL;
-static void _bt_scandel(IndexScanDesc scan, int op, BlockNumber blkno, OffsetNumber offno);
-static bool _bt_scantouched(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno);
+static void _bt_scandel(IndexScanDesc scan, int op, BlockNumber blkno, OffsetNumber offno);
+static bool _bt_scantouched(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno);
/*
- * _bt_regscan() -- register a new scan.
+ * _bt_regscan() -- register a new scan.
*/
void
_bt_regscan(IndexScanDesc scan)
{
- BTScanList new_el;
-
- new_el = (BTScanList) palloc(sizeof(BTScanListData));
- new_el->btsl_scan = scan;
- new_el->btsl_next = BTScans;
- BTScans = new_el;
+ BTScanList new_el;
+
+ new_el = (BTScanList) palloc(sizeof(BTScanListData));
+ new_el->btsl_scan = scan;
+ new_el->btsl_next = BTScans;
+ BTScans = new_el;
}
/*
- * _bt_dropscan() -- drop a scan from the scan list
+ * _bt_dropscan() -- drop a scan from the scan list
*/
void
_bt_dropscan(IndexScanDesc scan)
{
- BTScanList chk, last;
-
- last = (BTScanList) NULL;
- for (chk = BTScans;
- chk != (BTScanList) NULL && chk->btsl_scan != scan;
- chk = chk->btsl_next) {
- last = chk;
- }
-
- if (chk == (BTScanList) NULL)
- elog(WARN, "btree scan list trashed; can't find 0x%lx", scan);
-
- if (last == (BTScanList) NULL)
- BTScans = chk->btsl_next;
- else
- last->btsl_next = chk->btsl_next;
-
- pfree (chk);
+ BTScanList chk,
+ last;
+
+ last = (BTScanList) NULL;
+ for (chk = BTScans;
+ chk != (BTScanList) NULL && chk->btsl_scan != scan;
+ chk = chk->btsl_next)
+ {
+ last = chk;
+ }
+
+ if (chk == (BTScanList) NULL)
+ elog(WARN, "btree scan list trashed; can't find 0x%lx", scan);
+
+ if (last == (BTScanList) NULL)
+ BTScans = chk->btsl_next;
+ else
+ last->btsl_next = chk->btsl_next;
+
+ pfree(chk);
}
/*
- * _bt_adjscans() -- adjust all scans in the scan list to compensate
- * for a given deletion or insertion
+ * _bt_adjscans() -- adjust all scans in the scan list to compensate
+ * for a given deletion or insertion
*/
void
_bt_adjscans(Relation rel, ItemPointer tid, int op)
{
- BTScanList l;
- Oid relid;
-
- relid = rel->rd_id;
- for (l = BTScans; l != (BTScanList) NULL; l = l->btsl_next) {
- if (relid == l->btsl_scan->relation->rd_id)
- _bt_scandel(l->btsl_scan, op,
- ItemPointerGetBlockNumber(tid),
- ItemPointerGetOffsetNumber(tid));
- }
+ BTScanList l;
+ Oid relid;
+
+ relid = rel->rd_id;
+ for (l = BTScans; l != (BTScanList) NULL; l = l->btsl_next)
+ {
+ if (relid == l->btsl_scan->relation->rd_id)
+ _bt_scandel(l->btsl_scan, op,
+ ItemPointerGetBlockNumber(tid),
+ ItemPointerGetOffsetNumber(tid));
+ }
}
/*
- * _bt_scandel() -- adjust a single scan
+ * _bt_scandel() -- adjust a single scan
*
* because each index page is always maintained as an ordered array of
* index tuples, the index tuples on a given page shift beneath any
- * given scan. an index modification "behind" a scan position (i.e.,
+ * given scan. an index modification "behind" a scan position (i.e.,
* same page, lower or equal offset number) will therefore force us to
* adjust the scan in the following ways:
*
@@ -126,80 +130,85 @@ _bt_adjscans(Relation rel, ItemPointer tid, int op)
static void
_bt_scandel(IndexScanDesc scan, int op, BlockNumber blkno, OffsetNumber offno)
{
- ItemPointer current;
- Buffer buf;
- BTScanOpaque so;
-
- if (!_bt_scantouched(scan, blkno, offno))
- return;
-
- so = (BTScanOpaque) scan->opaque;
- buf = so->btso_curbuf;
-
- current = &(scan->currentItemData);
- if (ItemPointerIsValid(current)
- && ItemPointerGetBlockNumber(current) == blkno
- && ItemPointerGetOffsetNumber(current) >= offno) {
- switch (op) {
- case BT_INSERT:
- _bt_step(scan, &buf, ForwardScanDirection);
- break;
- case BT_DELETE:
- _bt_step(scan, &buf, BackwardScanDirection);
- break;
- default:
- elog(WARN, "_bt_scandel: bad operation '%d'", op);
- /*NOTREACHED*/
+ ItemPointer current;
+ Buffer buf;
+ BTScanOpaque so;
+
+ if (!_bt_scantouched(scan, blkno, offno))
+ return;
+
+ so = (BTScanOpaque) scan->opaque;
+ buf = so->btso_curbuf;
+
+ current = &(scan->currentItemData);
+ if (ItemPointerIsValid(current)
+ && ItemPointerGetBlockNumber(current) == blkno
+ && ItemPointerGetOffsetNumber(current) >= offno)
+ {
+ switch (op)
+ {
+ case BT_INSERT:
+ _bt_step(scan, &buf, ForwardScanDirection);
+ break;
+ case BT_DELETE:
+ _bt_step(scan, &buf, BackwardScanDirection);
+ break;
+ default:
+ elog(WARN, "_bt_scandel: bad operation '%d'", op);
+ /* NOTREACHED */
+ }
+ so->btso_curbuf = buf;
}
- so->btso_curbuf = buf;
- }
-
- current = &(scan->currentMarkData);
- if (ItemPointerIsValid(current)
- && ItemPointerGetBlockNumber(current) == blkno
- && ItemPointerGetOffsetNumber(current) >= offno) {
- ItemPointerData tmp;
- tmp = *current;
- *current = scan->currentItemData;
- scan->currentItemData = tmp;
- switch (op) {
- case BT_INSERT:
- _bt_step(scan, &buf, ForwardScanDirection);
- break;
- case BT_DELETE:
- _bt_step(scan, &buf, BackwardScanDirection);
- break;
- default:
- elog(WARN, "_bt_scandel: bad operation '%d'", op);
- /*NOTREACHED*/
+
+ current = &(scan->currentMarkData);
+ if (ItemPointerIsValid(current)
+ && ItemPointerGetBlockNumber(current) == blkno
+ && ItemPointerGetOffsetNumber(current) >= offno)
+ {
+ ItemPointerData tmp;
+
+ tmp = *current;
+ *current = scan->currentItemData;
+ scan->currentItemData = tmp;
+ switch (op)
+ {
+ case BT_INSERT:
+ _bt_step(scan, &buf, ForwardScanDirection);
+ break;
+ case BT_DELETE:
+ _bt_step(scan, &buf, BackwardScanDirection);
+ break;
+ default:
+ elog(WARN, "_bt_scandel: bad operation '%d'", op);
+ /* NOTREACHED */
+ }
+ so->btso_mrkbuf = buf;
+ tmp = *current;
+ *current = scan->currentItemData;
+ scan->currentItemData = tmp;
}
- so->btso_mrkbuf = buf;
- tmp = *current;
- *current = scan->currentItemData;
- scan->currentItemData = tmp;
- }
}
/*
- * _bt_scantouched() -- check to see if a scan is affected by a given
- * change to the index
+ * _bt_scantouched() -- check to see if a scan is affected by a given
+ * change to the index
*/
-static bool
+static bool
_bt_scantouched(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno)
{
- ItemPointer current;
-
- current = &(scan->currentItemData);
- if (ItemPointerIsValid(current)
- && ItemPointerGetBlockNumber(current) == blkno
- && ItemPointerGetOffsetNumber(current) >= offno)
- return (true);
-
- current = &(scan->currentMarkData);
- if (ItemPointerIsValid(current)
- && ItemPointerGetBlockNumber(current) == blkno
- && ItemPointerGetOffsetNumber(current) >= offno)
- return (true);
-
- return (false);
+ ItemPointer current;
+
+ current = &(scan->currentItemData);
+ if (ItemPointerIsValid(current)
+ && ItemPointerGetBlockNumber(current) == blkno
+ && ItemPointerGetOffsetNumber(current) >= offno)
+ return (true);
+
+ current = &(scan->currentMarkData);
+ if (ItemPointerIsValid(current)
+ && ItemPointerGetBlockNumber(current) == blkno
+ && ItemPointerGetOffsetNumber(current) >= offno)
+ return (true);
+
+ return (false);
}
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