database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-28 23:42:10 +03:00
Code Activity

Major overhaul of btree index code. Eliminate special BTP_CHAIN logic for

Browse Source 
duplicate keys by letting search go to the left rather than right when an
equal key is seen at an upper tree level.  Fix poor choice of page split
point (leading to insertion failures) that was forced by chaining logic.
Don't store leftmost key in non-leaf pages, since it's not necessary.
Don't create root page until something is first stored in the index, so an
unused index is now 8K not 16K.  (Doesn't seem to be as easy to get rid of
the metadata page, unfortunately.)  Massive cleanup of unreadable code,
fix poor, obsolete, and just plain wrong documentation and comments.
See src/backend/access/nbtree/README for the gory details.
This commit is contained in:
Tom Lane
2000-07-21 06:42:39 +00:00
parent c9537ca88f
commit 9e85183bfc
11 changed files with 1629 additions and 2859 deletions
Download Patch File Download Diff File Expand all files Collapse all files

135
src/backend/access/nbtree/nbtree.c
View File

@ -12,7 +12,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.61 2000/07/14 22:17:33 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.62 2000/07/21 06:42:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -26,6 +26,7 @@
#include "executor/executor.h"
#include "miscadmin.h"
bool BuildingBtree = false; /* see comment in btbuild() */
bool FastBuild = true; /* use sort/build instead of insertion
* build */
@ -206,8 +207,8 @@ btbuild(PG_FUNCTION_ARGS)
* btree pages - NULLs greater NOT_NULLs and NULL = NULL is TRUE.
* Sure, it's just rule for placing/finding items and no more -
* keytest'll return FALSE for a = 5 for items having 'a' isNULL.
* Look at _bt_skeycmp, _bt_compare and _bt_itemcmp for how it
* works. - vadim 03/23/97
* Look at _bt_compare for how it works.
* - vadim 03/23/97
*
* if (itup->t_info & INDEX_NULL_MASK) { pfree(itup); continue; }
*/
@ -321,14 +322,6 @@ btinsert(PG_FUNCTION_ARGS)
/* generate an index tuple */
itup = index_formtuple(RelationGetDescr(rel), datum, nulls);
itup->t_tid = *ht_ctid;
/*
* See comments in btbuild.
*
* if (itup->t_info & INDEX_NULL_MASK)
* PG_RETURN_POINTER((InsertIndexResult) NULL);
*/
btitem = _bt_formitem(itup);
res = _bt_doinsert(rel, btitem, rel->rd_uniqueindex, heapRel);
@ -357,10 +350,10 @@ btgettuple(PG_FUNCTION_ARGS)
if (ItemPointerIsValid(&(scan->currentItemData)))
{
/*
* Restore scan position using heap TID returned by previous call
* to btgettuple(). _bt_restscan() locks buffer.
* to btgettuple(). _bt_restscan() re-grabs the read lock on
* the buffer, too.
*/
_bt_restscan(scan);
res = _bt_next(scan, dir);
@ -369,8 +362,9 @@ btgettuple(PG_FUNCTION_ARGS)
res = _bt_first(scan, dir);
/*
* Save heap TID to use it in _bt_restscan. Unlock buffer before
* leaving index !
* Save heap TID to use it in _bt_restscan. Then release the read
* lock on the buffer so that we aren't blocking other backends.
* NOTE: we do keep the pin on the buffer!
*/
if (res)
{
@ -419,22 +413,6 @@ btrescan(PG_FUNCTION_ARGS)
so = (BTScanOpaque) scan->opaque;
/* we don't hold a read lock on the current page in the scan */
if (ItemPointerIsValid(iptr = &(scan->currentItemData)))
{
ReleaseBuffer(so->btso_curbuf);
so->btso_curbuf = InvalidBuffer;
ItemPointerSetInvalid(iptr);
}
/* and we don't hold a read lock on the last marked item in the scan */
if (ItemPointerIsValid(iptr = &(scan->currentMarkData)))
{
ReleaseBuffer(so->btso_mrkbuf);
so->btso_mrkbuf = InvalidBuffer;
ItemPointerSetInvalid(iptr);
}
if (so == NULL) /* if called from btbeginscan */
{
so = (BTScanOpaque) palloc(sizeof(BTScanOpaqueData));
@ -446,6 +424,21 @@ btrescan(PG_FUNCTION_ARGS)
scan->flags = 0x0;
}
/* we aren't holding any read locks, but gotta drop the pins */
if (ItemPointerIsValid(iptr = &(scan->currentItemData)))
{
ReleaseBuffer(so->btso_curbuf);
so->btso_curbuf = InvalidBuffer;
ItemPointerSetInvalid(iptr);
}
if (ItemPointerIsValid(iptr = &(scan->currentMarkData)))
{
ReleaseBuffer(so->btso_mrkbuf);
so->btso_mrkbuf = InvalidBuffer;
ItemPointerSetInvalid(iptr);
}
/*
* Reset the scan keys. Note that keys ordering stuff moved to
* _bt_first. - vadim 05/05/97
@ -472,7 +465,7 @@ btmovescan(IndexScanDesc scan, Datum v)
so = (BTScanOpaque) scan->opaque;
/* we don't hold a read lock on the current page in the scan */
/* we aren't holding any read locks, but gotta drop the pin */
if (ItemPointerIsValid(iptr = &(scan->currentItemData)))
{
ReleaseBuffer(so->btso_curbuf);
@ -480,7 +473,6 @@ btmovescan(IndexScanDesc scan, Datum v)
ItemPointerSetInvalid(iptr);
}
/* scan->keyData[0].sk_argument = v; */
so->keyData[0].sk_argument = v;
}
@ -496,7 +488,7 @@ btendscan(PG_FUNCTION_ARGS)
so = (BTScanOpaque) scan->opaque;
/* we don't hold any read locks */
/* we aren't holding any read locks, but gotta drop the pins */
if (ItemPointerIsValid(iptr = &(scan->currentItemData)))
{
if (BufferIsValid(so->btso_curbuf))
@ -534,7 +526,7 @@ btmarkpos(PG_FUNCTION_ARGS)
so = (BTScanOpaque) scan->opaque;
/* we don't hold any read locks */
/* we aren't holding any read locks, but gotta drop the pin */
if (ItemPointerIsValid(iptr = &(scan->currentMarkData)))
{
ReleaseBuffer(so->btso_mrkbuf);
@ -542,7 +534,7 @@ btmarkpos(PG_FUNCTION_ARGS)
ItemPointerSetInvalid(iptr);
}
/* bump pin on current buffer */
/* bump pin on current buffer for assignment to mark buffer */
if (ItemPointerIsValid(&(scan->currentItemData)))
{
so->btso_mrkbuf = ReadBuffer(scan->relation,
@ -566,7 +558,7 @@ btrestrpos(PG_FUNCTION_ARGS)
so = (BTScanOpaque) scan->opaque;
/* we don't hold any read locks */
/* we aren't holding any read locks, but gotta drop the pin */
if (ItemPointerIsValid(iptr = &(scan->currentItemData)))
{
ReleaseBuffer(so->btso_curbuf);
@ -579,7 +571,6 @@ btrestrpos(PG_FUNCTION_ARGS)
{
so->btso_curbuf = ReadBuffer(scan->relation,
BufferGetBlockNumber(so->btso_mrkbuf));
scan->currentItemData = scan->currentMarkData;
so->curHeapIptr = so->mrkHeapIptr;
}
@ -603,6 +594,9 @@ btdelete(PG_FUNCTION_ARGS)
PG_RETURN_VOID();
}
/*
* Restore scan position when btgettuple is called to continue a scan.
*/
static void
_bt_restscan(IndexScanDesc scan)
{
@ -618,7 +612,12 @@ _bt_restscan(IndexScanDesc scan)
BTItem item;
BlockNumber blkno;
LockBuffer(buf, BT_READ); /* lock buffer first! */
/*
* Get back the read lock we were holding on the buffer.
* (We still have a reference-count pin on it, though.)
*/
LockBuffer(buf, BT_READ);
page = BufferGetPage(buf);
maxoff = PageGetMaxOffsetNumber(page);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
@ -631,43 +630,40 @@ _bt_restscan(IndexScanDesc scan)
*/
if (!ItemPointerIsValid(&target))
{
ItemPointerSetOffsetNumber(&(scan->currentItemData),
OffsetNumberPrev(P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY));
ItemPointerSetOffsetNumber(current,
OffsetNumberPrev(P_FIRSTDATAKEY(opaque)));
return;
}
if (maxoff >= offnum)
/*
* The item we were on may have moved right due to insertions.
* Find it again.
*/
for (;;)
{
/*
* if the item is where we left it or has just moved right on this
* page, we're done
*/
/* Check for item on this page */
for (;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
item = (BTItem) PageGetItem(page, PageGetItemId(page, offnum));
if (item->bti_itup.t_tid.ip_blkid.bi_hi == \
target.ip_blkid.bi_hi && \
item->bti_itup.t_tid.ip_blkid.bi_lo == \
target.ip_blkid.bi_lo && \
if (item->bti_itup.t_tid.ip_blkid.bi_hi ==
target.ip_blkid.bi_hi &&
item->bti_itup.t_tid.ip_blkid.bi_lo ==
target.ip_blkid.bi_lo &&
item->bti_itup.t_tid.ip_posid == target.ip_posid)
{
current->ip_posid = offnum;
return;
}
}
}
/*
* By here, the item we're looking for moved right at least one page
*/
for (;;)
{
/*
* By here, the item we're looking for moved right at least one page
*/
if (P_RIGHTMOST(opaque))
elog(FATAL, "_bt_restscan: my bits moved right off the end of the world!\
\n\tRecreate index %s.", RelationGetRelationName(rel));
elog(FATAL, "_bt_restscan: my bits moved right off the end of the world!"
"\n\tRecreate index %s.", RelationGetRelationName(rel));
blkno = opaque->btpo_next;
_bt_relbuf(rel, buf, BT_READ);
@ -675,23 +671,8 @@ _bt_restscan(IndexScanDesc scan)
page = BufferGetPage(buf);
maxoff = PageGetMaxOffsetNumber(page);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
/* see if it's on this page */
for (offnum = P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
item = (BTItem) PageGetItem(page, PageGetItemId(page, offnum));
if (item->bti_itup.t_tid.ip_blkid.bi_hi == \
target.ip_blkid.bi_hi && \
item->bti_itup.t_tid.ip_blkid.bi_lo == \
target.ip_blkid.bi_lo && \
item->bti_itup.t_tid.ip_posid == target.ip_posid)
{
ItemPointerSet(current, blkno, offnum);
so->btso_curbuf = buf;
return;
}
}
offnum = P_FIRSTDATAKEY(opaque);
ItemPointerSet(current, blkno, offnum);
so->btso_curbuf = buf;
}
}