diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtscan.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtscan.c | 224 |
1 files changed, 0 insertions, 224 deletions
diff --git a/src/backend/access/nbtree/nbtscan.c b/src/backend/access/nbtree/nbtscan.c deleted file mode 100644 index e07914b3440..00000000000 --- a/src/backend/access/nbtree/nbtscan.c +++ /dev/null @@ -1,224 +0,0 @@ -/*------------------------------------------------------------------------- - * - * btscan.c - * manage scans on btrees. - * - * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.33 2001/01/24 19:42:48 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. - * Insertions and page splits are no problem because _bt_restscan() - * can figure out where the current item moved to, but if a deletion - * happens at or before the current scan position, we'd better do - * something to stay in sync. - * - * The routines in this file handle the problem for deletions issued - * by the current backend. Currently, that's all we need, since - * deletions are only done by VACUUM and it gets an exclusive lock. - * - * The scheme is to manage a list of active scans in the current backend. - * Whenever we remove a record from an index, 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. - * - *------------------------------------------------------------------------- - */ - -#include "postgres.h" - -#include "access/nbtree.h" - -typedef struct BTScanListData -{ - IndexScanDesc btsl_scan; - struct BTScanListData *btsl_next; -} BTScanListData; - -typedef BTScanListData *BTScanList; - -static BTScanList BTScans = (BTScanList) NULL; - -static void _bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno); - -/* - * AtEOXact_nbtree() --- clean up nbtree subsystem at xact abort or commit. - * - * This is here because it needs to touch this module's static var BTScans. - */ -void -AtEOXact_nbtree(void) -{ - - /* - * Note: these actions should only be necessary during xact abort; but - * they can't hurt during a commit. - */ - - /* - * Reset the active-scans list to empty. We do not need to free the - * list elements, because they're all palloc()'d, so they'll go away - * at end of transaction anyway. - */ - BTScans = NULL; - - /* If we were building a btree, we ain't anymore. */ - BuildingBtree = false; -} - -/* - * _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; -} - -/* - * _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(ERROR, "btree scan list trashed; can't find 0x%p", (void *) 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 - */ -void -_bt_adjscans(Relation rel, ItemPointer tid) -{ - BTScanList l; - Oid relid; - - relid = RelationGetRelid(rel); - for (l = BTScans; l != (BTScanList) NULL; l = l->btsl_next) - { - if (relid == RelationGetRelid(l->btsl_scan->relation)) - _bt_scandel(l->btsl_scan, - ItemPointerGetBlockNumber(tid), - ItemPointerGetOffsetNumber(tid)); - } -} - -/* - * _bt_scandel() -- adjust a single scan on deletion - * - */ -static void -_bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) -{ - ItemPointer current; - Buffer buf; - BTScanOpaque so; - OffsetNumber start; - Page page; - BTPageOpaque opaque; - - so = (BTScanOpaque) scan->opaque; - buf = so->btso_curbuf; - - current = &(scan->currentItemData); - if (ItemPointerIsValid(current) - && ItemPointerGetBlockNumber(current) == blkno - && ItemPointerGetOffsetNumber(current) >= offno) - { - page = BufferGetPage(buf); - opaque = (BTPageOpaque) PageGetSpecialPointer(page); - start = P_FIRSTDATAKEY(opaque); - if (ItemPointerGetOffsetNumber(current) == start) - ItemPointerSetInvalid(&(so->curHeapIptr)); - else - { - - /* - * We have to lock buffer before _bt_step and unlock it after - * that. - */ - LockBuffer(buf, BT_READ); - _bt_step(scan, &buf, BackwardScanDirection); - if (ItemPointerIsValid(current)) - { - Page pg = BufferGetPage(buf); - BTItem btitem = (BTItem) PageGetItem(pg, - PageGetItemId(pg, ItemPointerGetOffsetNumber(current))); - - so->curHeapIptr = btitem->bti_itup.t_tid; - LockBuffer(buf, BUFFER_LOCK_UNLOCK); - } - } - } - - current = &(scan->currentMarkData); - if (ItemPointerIsValid(current) - && ItemPointerGetBlockNumber(current) == blkno - && ItemPointerGetOffsetNumber(current) >= offno) - { - page = BufferGetPage(so->btso_mrkbuf); - opaque = (BTPageOpaque) PageGetSpecialPointer(page); - start = P_FIRSTDATAKEY(opaque); - - if (ItemPointerGetOffsetNumber(current) == start) - ItemPointerSetInvalid(&(so->mrkHeapIptr)); - else - { - ItemPointerData tmp; - - tmp = *current; - *current = scan->currentItemData; - scan->currentItemData = tmp; - so->btso_curbuf = so->btso_mrkbuf; - so->btso_mrkbuf = buf; - buf = so->btso_curbuf; - LockBuffer(buf, BT_READ); /* as above */ - - _bt_step(scan, &buf, BackwardScanDirection); - - so->btso_curbuf = so->btso_mrkbuf; - so->btso_mrkbuf = buf; - tmp = *current; - *current = scan->currentItemData; - scan->currentItemData = tmp; - if (ItemPointerIsValid(current)) - { - Page pg = BufferGetPage(buf); - BTItem btitem = (BTItem) PageGetItem(pg, - PageGetItemId(pg, ItemPointerGetOffsetNumber(current))); - - so->mrkHeapIptr = btitem->bti_itup.t_tid; - LockBuffer(buf, BUFFER_LOCK_UNLOCK); /* as above */ - } - } - } -} |