diff options
Diffstat (limited to 'src/backend/access')
| -rw-r--r-- | src/backend/access/nbtree/nbtree.c | 2 | ||||
| -rw-r--r-- | src/backend/access/nbtree/nbtscan.c | 70 | ||||
| -rw-r--r-- | src/backend/access/nbtree/nbtsearch.c | 4 |
3 files changed, 64 insertions, 12 deletions
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c index 0624bd06a87..142eafec029 100644 --- a/src/backend/access/nbtree/nbtree.c +++ b/src/backend/access/nbtree/nbtree.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.13 1997/02/12 05:04:17 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.14 1997/02/18 17:13:42 momjian Exp $ * * NOTES * This file contains only the public interface routines. diff --git a/src/backend/access/nbtree/nbtscan.c b/src/backend/access/nbtree/nbtscan.c index 3de9f39d325..5e23fe13d7b 100644 --- a/src/backend/access/nbtree/nbtscan.c +++ b/src/backend/access/nbtree/nbtscan.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.6 1996/11/15 18:37:00 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.7 1997/02/18 17:13:45 momjian Exp $ * * * NOTES @@ -40,7 +40,10 @@ typedef struct BTScanListData { typedef BTScanListData *BTScanList; 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); + /* * _bt_regscan() -- register a new scan. */ @@ -81,8 +84,12 @@ _bt_dropscan(IndexScanDesc scan) pfree (chk); } +/* + * _bt_adjscans() -- adjust all scans in the scan list to compensate + * for a given deletion or insertion + */ void -_bt_adjscans(Relation rel, ItemPointer tid) +_bt_adjscans(Relation rel, ItemPointer tid, int op) { BTScanList l; Oid relid; @@ -90,13 +97,34 @@ _bt_adjscans(Relation rel, ItemPointer tid) 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, ItemPointerGetBlockNumber(tid), + _bt_scandel(l->btsl_scan, op, + ItemPointerGetBlockNumber(tid), ItemPointerGetOffsetNumber(tid)); } } -void -_bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) +/* + * _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., + * same page, lower or equal offset number) will therefore force us to + * adjust the scan in the following ways: + * + * - on insertion, we shift the scan forward by one item. + * - on deletion, we shift the scan backward by one item. + * + * note that: + * + * - we need not worry about the actual ScanDirection of the scan + * itself, since the problem is that the "current" scan position has + * shifted. + * - modifications "ahead" of our scan position do not change the + * array index of the current scan position and so can be ignored. + */ +static void +_bt_scandel(IndexScanDesc scan, int op, BlockNumber blkno, OffsetNumber offno) { ItemPointer current; Buffer buf; @@ -112,7 +140,17 @@ _bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) if (ItemPointerIsValid(current) && ItemPointerGetBlockNumber(current) == blkno && ItemPointerGetOffsetNumber(current) >= offno) { - _bt_step(scan, &buf, BackwardScanDirection); + 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; } @@ -124,7 +162,17 @@ _bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) tmp = *current; *current = scan->currentItemData; scan->currentItemData = tmp; - _bt_step(scan, &buf, BackwardScanDirection); + 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; @@ -132,7 +180,11 @@ _bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) } } -bool +/* + * _bt_scantouched() -- check to see if a scan is affected by a given + * change to the index + */ +static bool _bt_scantouched(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) { ItemPointer current; diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c index 569a9e7e7f8..94521ff1c0b 100644 --- a/src/backend/access/nbtree/nbtsearch.c +++ b/src/backend/access/nbtree/nbtsearch.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.13 1997/01/05 10:56:36 vadim Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.14 1997/02/18 17:13:48 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -332,7 +332,7 @@ _bt_binsrch(Relation rel, else if (result < 0) high = mid - 1; else - return (_bt_firsteq(rel, itupdesc, page, keysz, scankey, mid)); + return (_bt_firsteq(rel, itupdesc, page, keysz, scankey, mid)); } /* |