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Commitb4297c1

Browse files
author
Neil Conway
committed
This patch makes some improvements to the rtree index implementation:
(1) Keep a pin on the scan's current buffer and mark buffer. Thisavoids the need to do a ReadBuffer() for each tuple produced by thescan. Since ReadBuffer() is expensive, this is a significant win.(2) Convert a ReleaseBuffer(); ReadBuffer() pair intoReleaseAndReadBuffer(). Surely not a huge win, but it saves a lockacquire/release...(3) Remove a bunch of duplicated code in rtget.c; make rtnext() handleboth the "initial result" and "subsequent result" cases.(4) Add support for index tuple killing(5) Remove rtscancache(): it is dead code, for the same reason thatgistscancache() is dead code (an index scan ought not be invoked withNoMovementScanDirection).The end result is about a 10% improvement in rtree index scan perf,according to contrib/rtree_gist/bench.
1 parent1f5299b commitb4297c1

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4 files changed

+157
-154
lines changed

4 files changed

+157
-154
lines changed

‎src/backend/access/rtree/rtget.c‎

Lines changed: 102 additions & 139 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/rtree/rtget.c,v 1.33 2004/12/31 21:59:26 pgsql Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/rtree/rtget.c,v 1.34 2005/01/18 23:25:43 neilc Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -19,10 +19,8 @@
1919
#include"access/relscan.h"
2020
#include"access/rtree.h"
2121

22-
staticOffsetNumberfindnext(IndexScanDescs,Pagep,OffsetNumbern,
22+
staticOffsetNumberfindnext(IndexScanDescs,OffsetNumbern,
2323
ScanDirectiondir);
24-
staticboolrtscancache(IndexScanDescs,ScanDirectiondir);
25-
staticboolrtfirst(IndexScanDescs,ScanDirectiondir);
2624
staticboolrtnext(IndexScanDescs,ScanDirectiondir);
2725

2826

@@ -31,138 +29,106 @@ rtgettuple(PG_FUNCTION_ARGS)
3129
{
3230
IndexScanDescs= (IndexScanDesc)PG_GETARG_POINTER(0);
3331
ScanDirectiondir= (ScanDirection)PG_GETARG_INT32(1);
34-
boolres;
35-
36-
/* if we have it cached in the scan desc, just return the value */
37-
if (rtscancache(s,dir))
38-
PG_RETURN_BOOL(true);
39-
40-
/* not cached, so we'll have to do some work */
41-
if (ItemPointerIsValid(&(s->currentItemData)))
42-
res=rtnext(s,dir);
43-
else
44-
res=rtfirst(s,dir);
45-
PG_RETURN_BOOL(res);
46-
}
47-
48-
staticbool
49-
rtfirst(IndexScanDescs,ScanDirectiondir)
50-
{
51-
Bufferb;
52-
Pagep;
53-
OffsetNumbern;
54-
OffsetNumbermaxoff;
55-
RTreePageOpaquepo;
32+
Pagepage;
33+
OffsetNumberoffnum;
5634
RTreeScanOpaqueso;
57-
RTSTACK*stk;
58-
BlockNumberblk;
59-
IndexTupleit;
6035

61-
b=ReadBuffer(s->indexRelation,P_ROOT);
62-
p=BufferGetPage(b);
63-
po= (RTreePageOpaque)PageGetSpecialPointer(p);
6436
so= (RTreeScanOpaque)s->opaque;
6537

66-
for (;;)
38+
/*
39+
* If we've already produced a tuple and the executor has informed
40+
* us that it should be marked "killed", do so know.
41+
*/
42+
if (s->kill_prior_tuple&&ItemPointerIsValid(&(s->currentItemData)))
6743
{
68-
maxoff=PageGetMaxOffsetNumber(p);
69-
if (ScanDirectionIsBackward(dir))
70-
n=findnext(s,p,maxoff,dir);
71-
else
72-
n=findnext(s,p,FirstOffsetNumber,dir);
73-
74-
while (n<FirstOffsetNumber||n>maxoff)
75-
{
76-
ReleaseBuffer(b);
77-
if (so->s_stack==NULL)
78-
return false;
79-
80-
stk=so->s_stack;
81-
b=ReadBuffer(s->indexRelation,stk->rts_blk);
82-
p=BufferGetPage(b);
83-
po= (RTreePageOpaque)PageGetSpecialPointer(p);
84-
maxoff=PageGetMaxOffsetNumber(p);
44+
offnum=ItemPointerGetOffsetNumber(&(s->currentItemData));
45+
page=BufferGetPage(so->curbuf);
46+
PageGetItemId(page,offnum)->lp_flags |=LP_DELETE;
47+
SetBufferCommitInfoNeedsSave(so->curbuf);
48+
}
8549

86-
if (ScanDirectionIsBackward(dir))
87-
n=OffsetNumberPrev(stk->rts_child);
88-
else
89-
n=OffsetNumberNext(stk->rts_child);
90-
so->s_stack=stk->rts_parent;
91-
pfree(stk);
50+
/*
51+
* Get the next tuple that matches the search key; if asked to
52+
* skip killed tuples, find the first non-killed tuple that
53+
* matches. Return as soon as we've run out of matches or we've
54+
* found an acceptable match.
55+
*/
56+
for (;;)
57+
{
58+
boolres=rtnext(s,dir);
9259

93-
n=findnext(s,p,n,dir);
94-
}
95-
if (po->flags&F_LEAF)
60+
if (res== true&&s->ignore_killed_tuples)
9661
{
97-
ItemPointerSet(&(s->currentItemData),BufferGetBlockNumber(b),n);
98-
99-
it= (IndexTuple)PageGetItem(p,PageGetItemId(p,n));
100-
101-
s->xs_ctup.t_self=it->t_tid;
102-
103-
ReleaseBuffer(b);
104-
return true;
62+
offnum=ItemPointerGetOffsetNumber(&(s->currentItemData));
63+
page=BufferGetPage(so->curbuf);
64+
if (ItemIdDeleted(PageGetItemId(page,offnum)))
65+
continue;
10566
}
106-
else
107-
{
108-
stk= (RTSTACK*)palloc(sizeof(RTSTACK));
109-
stk->rts_child=n;
110-
stk->rts_blk=BufferGetBlockNumber(b);
111-
stk->rts_parent=so->s_stack;
112-
so->s_stack=stk;
113-
114-
it= (IndexTuple)PageGetItem(p,PageGetItemId(p,n));
115-
blk=ItemPointerGetBlockNumber(&(it->t_tid));
11667

117-
ReleaseBuffer(b);
118-
b=ReadBuffer(s->indexRelation,blk);
119-
p=BufferGetPage(b);
120-
po= (RTreePageOpaque)PageGetSpecialPointer(p);
121-
}
68+
PG_RETURN_BOOL(res);
12269
}
12370
}
12471

12572
staticbool
12673
rtnext(IndexScanDescs,ScanDirectiondir)
12774
{
128-
Bufferb;
12975
Pagep;
13076
OffsetNumbern;
131-
OffsetNumbermaxoff;
13277
RTreePageOpaquepo;
13378
RTreeScanOpaqueso;
134-
RTSTACK*stk;
135-
BlockNumberblk;
136-
IndexTupleit;
13779

138-
blk=ItemPointerGetBlockNumber(&(s->currentItemData));
139-
n=ItemPointerGetOffsetNumber(&(s->currentItemData));
80+
so= (RTreeScanOpaque)s->opaque;
14081

141-
if (ScanDirectionIsForward(dir))
142-
n=OffsetNumberNext(n);
143-
else
144-
n=OffsetNumberPrev(n);
82+
if (!ItemPointerIsValid(&(s->currentItemData)))
83+
{
84+
/* first call: start at the root */
85+
Assert(BufferIsValid(so->curbuf)== false);
86+
so->curbuf=ReadBuffer(s->indexRelation,P_ROOT);
87+
}
14588

146-
b=ReadBuffer(s->indexRelation,blk);
147-
p=BufferGetPage(b);
89+
p=BufferGetPage(so->curbuf);
14890
po= (RTreePageOpaque)PageGetSpecialPointer(p);
149-
so= (RTreeScanOpaque)s->opaque;
91+
92+
if (!ItemPointerIsValid(&(s->currentItemData)))
93+
{
94+
/* first call: start at first/last offset */
95+
if (ScanDirectionIsForward(dir))
96+
n=FirstOffsetNumber;
97+
else
98+
n=PageGetMaxOffsetNumber(p);
99+
}
100+
else
101+
{
102+
/* go on to the next offset */
103+
n=ItemPointerGetOffsetNumber(&(s->currentItemData));
104+
if (ScanDirectionIsForward(dir))
105+
n=OffsetNumberNext(n);
106+
else
107+
n=OffsetNumberPrev(n);
108+
}
150109

151110
for (;;)
152111
{
153-
maxoff=PageGetMaxOffsetNumber(p);
154-
n=findnext(s,p,n,dir);
112+
IndexTupleit;
113+
RTSTACK*stk;
114+
115+
n=findnext(s,n,dir);
155116

156-
while (n<FirstOffsetNumber||n>maxoff)
117+
/* no match on this page, so read in the next stack entry */
118+
if (n==InvalidOffsetNumber)
157119
{
158-
ReleaseBuffer(b);
120+
/* if out of stack entries, we're done */
159121
if (so->s_stack==NULL)
122+
{
123+
ReleaseBuffer(so->curbuf);
124+
so->curbuf=InvalidBuffer;
160125
return false;
126+
}
161127

162128
stk=so->s_stack;
163-
b=ReadBuffer(s->indexRelation,stk->rts_blk);
164-
p=BufferGetPage(b);
165-
maxoff=PageGetMaxOffsetNumber(p);
129+
so->curbuf=ReleaseAndReadBuffer(so->curbuf,s->indexRelation,
130+
stk->rts_blk);
131+
p=BufferGetPage(so->curbuf);
166132
po= (RTreePageOpaque)PageGetSpecialPointer(p);
167133

168134
if (ScanDirectionIsBackward(dir))
@@ -172,33 +138,41 @@ rtnext(IndexScanDesc s, ScanDirection dir)
172138
so->s_stack=stk->rts_parent;
173139
pfree(stk);
174140

175-
n=findnext(s,p,n,dir);
141+
continue;
176142
}
143+
177144
if (po->flags&F_LEAF)
178145
{
179-
ItemPointerSet(&(s->currentItemData),BufferGetBlockNumber(b),n);
180-
146+
ItemPointerSet(&(s->currentItemData),
147+
BufferGetBlockNumber(so->curbuf),
148+
n);
181149
it= (IndexTuple)PageGetItem(p,PageGetItemId(p,n));
182-
183150
s->xs_ctup.t_self=it->t_tid;
184-
185-
ReleaseBuffer(b);
186151
return true;
187152
}
188153
else
189154
{
155+
BlockNumberblk;
156+
190157
stk= (RTSTACK*)palloc(sizeof(RTSTACK));
191158
stk->rts_child=n;
192-
stk->rts_blk=BufferGetBlockNumber(b);
159+
stk->rts_blk=BufferGetBlockNumber(so->curbuf);
193160
stk->rts_parent=so->s_stack;
194161
so->s_stack=stk;
195162

196163
it= (IndexTuple)PageGetItem(p,PageGetItemId(p,n));
197164
blk=ItemPointerGetBlockNumber(&(it->t_tid));
198165

199-
ReleaseBuffer(b);
200-
b=ReadBuffer(s->indexRelation,blk);
201-
p=BufferGetPage(b);
166+
/*
167+
* Note that we release the pin on the page as we descend
168+
* down the tree, even though there's a good chance we'll
169+
* eventually need to re-read the buffer later in this
170+
* scan. This may or may not be optimal, but it doesn't
171+
* seem likely to make a huge performance difference
172+
* either way.
173+
*/
174+
so->curbuf=ReleaseAndReadBuffer(so->curbuf,s->indexRelation,blk);
175+
p=BufferGetPage(so->curbuf);
202176
po= (RTreePageOpaque)PageGetSpecialPointer(p);
203177

204178
if (ScanDirectionIsBackward(dir))
@@ -209,17 +183,26 @@ rtnext(IndexScanDesc s, ScanDirection dir)
209183
}
210184
}
211185

186+
/*
187+
* Return the offset of the next matching index entry. We begin the
188+
* search at offset "n" and search for matches in the direction
189+
* "dir". If no more matching entries are found on the page,
190+
* InvalidOffsetNumber is returned.
191+
*/
212192
staticOffsetNumber
213-
findnext(IndexScanDescs,Pagep,OffsetNumbern,ScanDirectiondir)
193+
findnext(IndexScanDescs,OffsetNumbern,ScanDirectiondir)
214194
{
215195
OffsetNumbermaxoff;
216196
IndexTupleit;
217197
RTreePageOpaquepo;
218198
RTreeScanOpaqueso;
199+
Pagep;
200+
201+
so= (RTreeScanOpaque)s->opaque;
202+
p=BufferGetPage(so->curbuf);
219203

220204
maxoff=PageGetMaxOffsetNumber(p);
221205
po= (RTreePageOpaque)PageGetSpecialPointer(p);
222-
so= (RTreeScanOpaque)s->opaque;
223206

224207
/*
225208
* If we modified the index during the scan, we may have a pointer to
@@ -256,28 +239,8 @@ findnext(IndexScanDesc s, Page p, OffsetNumber n, ScanDirection dir)
256239
n=OffsetNumberNext(n);
257240
}
258241

259-
returnn;
260-
}
261-
262-
staticbool
263-
rtscancache(IndexScanDescs,ScanDirectiondir)
264-
{
265-
Bufferb;
266-
Pagep;
267-
OffsetNumbern;
268-
IndexTupleit;
269-
270-
if (!(ScanDirectionIsNoMovement(dir)
271-
&&ItemPointerIsValid(&(s->currentItemData))))
272-
return false;
273-
274-
b=ReadBuffer(s->indexRelation,
275-
ItemPointerGetBlockNumber(&(s->currentItemData)));
276-
p=BufferGetPage(b);
277-
n=ItemPointerGetOffsetNumber(&(s->currentItemData));
278-
it= (IndexTuple)PageGetItem(p,PageGetItemId(p,n));
279-
s->xs_ctup.t_self=it->t_tid;
280-
ReleaseBuffer(b);
281-
282-
return true;
242+
if (n >=FirstOffsetNumber&&n <=maxoff)
243+
returnn;/* found a match on this page */
244+
else
245+
returnInvalidOffsetNumber;/* no match, go to next page */
283246
}

‎src/backend/access/rtree/rtree.c‎

Lines changed: 3 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/rtree/rtree.c,v 1.85 2004/12/31 21:59:26 pgsql Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/rtree/rtree.c,v 1.86 2005/01/18 23:25:47 neilc Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -280,12 +280,8 @@ rtdoinsert(Relation r, IndexTuple itup, RTSTATE *rtstate)
280280

281281
do
282282
{
283-
/* let go of current buffer before getting next */
284-
if (buffer!=InvalidBuffer)
285-
ReleaseBuffer(buffer);
286-
287-
/* get next buffer */
288-
buffer=ReadBuffer(r,blk);
283+
/* release the current buffer, read in the next one */
284+
buffer=ReleaseAndReadBuffer(buffer,r,blk);
289285
page= (Page)BufferGetPage(buffer);
290286

291287
opaque= (RTreePageOpaque)PageGetSpecialPointer(page);

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