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Commitdefe934

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Make the world safe for full_page_writes. Allow XLOG records that try to
update no-longer-existing pages to fall through as no-ops, but make a noteof each page number referenced by such records. If we don't see a laterXLOG entry dropping the table or truncating away the page, complain atthe end of XLOG replay. Since this fixes the known failure mode forfull_page_writes = off, revert my previous band-aid patch that disabledthat GUC variable.
1 parent0fcc3c2 commitdefe934

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4 files changed

+226
-22
lines changed

4 files changed

+226
-22
lines changed

‎src/backend/access/transam/xlog.c‎

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.234 2006/04/05 03:34:05 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.235 2006/04/14 20:27:24 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -980,7 +980,8 @@ XLogCheckBuffer(XLogRecData *rdata,
980980
*/
981981
*lsn=page->pd_lsn;
982982

983-
if (XLByteLE(page->pd_lsn,RedoRecPtr))
983+
if (fullPageWrites&&
984+
XLByteLE(page->pd_lsn,RedoRecPtr))
984985
{
985986
/*
986987
* The page needs to be backed up, so set up *bkpb
@@ -4786,6 +4787,12 @@ StartupXLOG(void)
47864787
RmgrTable[rmid].rm_cleanup();
47874788
}
47884789

4790+
/*
4791+
* Check to see if the XLOG sequence contained any unresolved
4792+
* references to uninitialized pages.
4793+
*/
4794+
XLogCheckInvalidPages();
4795+
47894796
/*
47904797
* Reset pgstat data, because it may be invalid after recovery.
47914798
*/

‎src/backend/access/transam/xlogutils.c‎

Lines changed: 209 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
1212
* Portions Copyright (c) 1994, Regents of the University of California
1313
*
14-
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.43 2006/03/31 23:32:06 tgl Exp $
14+
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.44 2006/04/14 20:27:24 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
@@ -24,6 +24,176 @@
2424
#include"utils/hsearch.h"
2525

2626

27+
/*
28+
* During XLOG replay, we may see XLOG records for incremental updates of
29+
* pages that no longer exist, because their relation was later dropped or
30+
* truncated. (Note: this is only possible when full_page_writes = OFF,
31+
* since when it's ON, the first reference we see to a page should always
32+
* be a full-page rewrite not an incremental update.) Rather than simply
33+
* ignoring such records, we make a note of the referenced page, and then
34+
* complain if we don't actually see a drop or truncate covering the page
35+
* later in replay.
36+
*/
37+
typedefstructxl_invalid_page_key
38+
{
39+
RelFileNodenode;/* the relation */
40+
BlockNumberblkno;/* the page */
41+
}xl_invalid_page_key;
42+
43+
typedefstructxl_invalid_page
44+
{
45+
xl_invalid_page_keykey;/* hash key ... must be first */
46+
boolpresent;/* page existed but contained zeroes */
47+
}xl_invalid_page;
48+
49+
staticHTAB*invalid_page_tab=NULL;
50+
51+
52+
/* Log a reference to an invalid page */
53+
staticvoid
54+
log_invalid_page(RelFileNodenode,BlockNumberblkno,boolpresent)
55+
{
56+
xl_invalid_page_keykey;
57+
xl_invalid_page*hentry;
58+
boolfound;
59+
60+
/*
61+
* Log references to invalid pages at DEBUG1 level. This allows some
62+
* tracing of the cause (note the elog context mechanism will tell us
63+
* something about the XLOG record that generated the reference).
64+
*/
65+
if (present)
66+
elog(DEBUG1,"page %u of relation %u/%u/%u is uninitialized",
67+
blkno,node.spcNode,node.dbNode,node.relNode);
68+
else
69+
elog(DEBUG1,"page %u of relation %u/%u/%u does not exist",
70+
blkno,node.spcNode,node.dbNode,node.relNode);
71+
72+
if (invalid_page_tab==NULL)
73+
{
74+
/* create hash table when first needed */
75+
HASHCTLctl;
76+
77+
memset(&ctl,0,sizeof(ctl));
78+
ctl.keysize=sizeof(xl_invalid_page_key);
79+
ctl.entrysize=sizeof(xl_invalid_page);
80+
ctl.hash=tag_hash;
81+
82+
invalid_page_tab=hash_create("XLOG invalid-page table",
83+
100,
84+
&ctl,
85+
HASH_ELEM |HASH_FUNCTION);
86+
}
87+
88+
/* we currently assume xl_invalid_page_key contains no padding */
89+
key.node=node;
90+
key.blkno=blkno;
91+
hentry= (xl_invalid_page*)
92+
hash_search(invalid_page_tab, (void*)&key,HASH_ENTER,&found);
93+
94+
if (!found)
95+
{
96+
/* hash_search already filled in the key */
97+
hentry->present=present;
98+
}
99+
else
100+
{
101+
/* repeat reference ... leave "present" as it was */
102+
}
103+
}
104+
105+
/* Forget any invalid pages >= minblkno, because they've been dropped */
106+
staticvoid
107+
forget_invalid_pages(RelFileNodenode,BlockNumberminblkno)
108+
{
109+
HASH_SEQ_STATUSstatus;
110+
xl_invalid_page*hentry;
111+
112+
if (invalid_page_tab==NULL)
113+
return;/* nothing to do */
114+
115+
hash_seq_init(&status,invalid_page_tab);
116+
117+
while ((hentry= (xl_invalid_page*)hash_seq_search(&status))!=NULL)
118+
{
119+
if (RelFileNodeEquals(hentry->key.node,node)&&
120+
hentry->key.blkno >=minblkno)
121+
{
122+
elog(DEBUG2,"page %u of relation %u/%u/%u has been dropped",
123+
hentry->key.blkno,hentry->key.node.spcNode,
124+
hentry->key.node.dbNode,hentry->key.node.relNode);
125+
126+
if (hash_search(invalid_page_tab,
127+
(void*)&hentry->key,
128+
HASH_REMOVE,NULL)==NULL)
129+
elog(ERROR,"hash table corrupted");
130+
}
131+
}
132+
}
133+
134+
/* Forget any invalid pages in a whole database */
135+
staticvoid
136+
forget_invalid_pages_db(Oiddbid)
137+
{
138+
HASH_SEQ_STATUSstatus;
139+
xl_invalid_page*hentry;
140+
141+
if (invalid_page_tab==NULL)
142+
return;/* nothing to do */
143+
144+
hash_seq_init(&status,invalid_page_tab);
145+
146+
while ((hentry= (xl_invalid_page*)hash_seq_search(&status))!=NULL)
147+
{
148+
if (hentry->key.node.dbNode==dbid)
149+
{
150+
elog(DEBUG2,"page %u of relation %u/%u/%u has been dropped",
151+
hentry->key.blkno,hentry->key.node.spcNode,
152+
hentry->key.node.dbNode,hentry->key.node.relNode);
153+
154+
if (hash_search(invalid_page_tab,
155+
(void*)&hentry->key,
156+
HASH_REMOVE,NULL)==NULL)
157+
elog(ERROR,"hash table corrupted");
158+
}
159+
}
160+
}
161+
162+
/* Complain about any remaining invalid-page entries */
163+
void
164+
XLogCheckInvalidPages(void)
165+
{
166+
HASH_SEQ_STATUSstatus;
167+
xl_invalid_page*hentry;
168+
boolfoundone= false;
169+
170+
if (invalid_page_tab==NULL)
171+
return;/* nothing to do */
172+
173+
hash_seq_init(&status,invalid_page_tab);
174+
175+
/*
176+
* Our strategy is to emit WARNING messages for all remaining entries
177+
* and only PANIC after we've dumped all the available info.
178+
*/
179+
while ((hentry= (xl_invalid_page*)hash_seq_search(&status))!=NULL)
180+
{
181+
if (hentry->present)
182+
elog(WARNING,"page %u of relation %u/%u/%u was uninitialized",
183+
hentry->key.blkno,hentry->key.node.spcNode,
184+
hentry->key.node.dbNode,hentry->key.node.relNode);
185+
else
186+
elog(WARNING,"page %u of relation %u/%u/%u did not exist",
187+
hentry->key.blkno,hentry->key.node.spcNode,
188+
hentry->key.node.dbNode,hentry->key.node.relNode);
189+
foundone= true;
190+
}
191+
192+
if (foundone)
193+
elog(PANIC,"WAL contains references to invalid pages");
194+
}
195+
196+
27197
/*
28198
* XLogReadBuffer
29199
*Read a page during XLOG replay
@@ -40,12 +210,11 @@
40210
* the page being "new" (all zeroes).
41211
*
42212
* If "init" is false then the caller needs the page to be valid already.
43-
* If the page doesn't exist or contains zeroes, we report failure.
44-
*
45-
* If the return value is InvalidBuffer (only possible when init = false),
46-
* the caller should silently skip the update on this page. This currently
47-
* never happens, but we retain it as part of the API spec for possible future
48-
* use.
213+
* If the page doesn't exist or contains zeroes, we return InvalidBuffer.
214+
* In this case the caller should silently skip the update on this page.
215+
* (In this situation, we expect that the page was later dropped or truncated.
216+
* If we don't see evidence of that later in the WAL sequence, we'll complain
217+
* at the end of WAL replay.)
49218
*/
50219
Buffer
51220
XLogReadBuffer(Relationreln,BlockNumberblkno,boolinit)
@@ -64,9 +233,10 @@ XLogReadBuffer(Relation reln, BlockNumber blkno, bool init)
64233
{
65234
/* hm, page doesn't exist in file */
66235
if (!init)
67-
elog(PANIC,"block %u of relation %u/%u/%u does not exist",
68-
blkno,reln->rd_node.spcNode,
69-
reln->rd_node.dbNode,reln->rd_node.relNode);
236+
{
237+
log_invalid_page(reln->rd_node,blkno, false);
238+
returnInvalidBuffer;
239+
}
70240
/* OK to extend the file */
71241
/* we do this in recovery only - no rel-extension lock needed */
72242
Assert(InRecovery);
@@ -89,9 +259,11 @@ XLogReadBuffer(Relation reln, BlockNumber blkno, bool init)
89259
Pagepage= (Page)BufferGetPage(buffer);
90260

91261
if (PageIsNew((PageHeader)page))
92-
elog(PANIC,"block %u of relation %u/%u/%u is uninitialized",
93-
blkno,reln->rd_node.spcNode,
94-
reln->rd_node.dbNode,reln->rd_node.relNode);
262+
{
263+
UnlockReleaseBuffer(buffer);
264+
log_invalid_page(reln->rd_node,blkno, true);
265+
returnInvalidBuffer;
266+
}
95267
}
96268

97269
returnbuffer;
@@ -195,6 +367,7 @@ void
195367
XLogInitRelationCache(void)
196368
{
197369
_xl_init_rel_cache();
370+
invalid_page_tab=NULL;
198371
}
199372

200373
void
@@ -300,22 +473,26 @@ XLogOpenRelation(RelFileNode rnode)
300473
*
301474
* Currently, we don't bother to physically remove the relation from the
302475
* cache, we just let it age out normally.
476+
*
477+
* This also takes care of removing any open "invalid-page" records for
478+
* the relation.
303479
*/
304480
void
305481
XLogDropRelation(RelFileNodernode)
306482
{
307-
XLogRelDesc*rdesc;
308483
XLogRelCacheEntry*hentry;
309484

310485
hentry= (XLogRelCacheEntry*)
311486
hash_search(_xlrelcache, (void*)&rnode,HASH_FIND,NULL);
312487

313-
if (!hentry)
314-
return;/* not in cache so no work */
488+
if (hentry)
489+
{
490+
XLogRelDesc*rdesc=hentry->rdesc;
315491

316-
rdesc=hentry->rdesc;
492+
RelationCloseSmgr(&(rdesc->reldata));
493+
}
317494

318-
RelationCloseSmgr(&(rdesc->reldata));
495+
forget_invalid_pages(rnode,0);
319496
}
320497

321498
/*
@@ -338,4 +515,18 @@ XLogDropDatabase(Oid dbid)
338515
if (hentry->rnode.dbNode==dbid)
339516
RelationCloseSmgr(&(rdesc->reldata));
340517
}
518+
519+
forget_invalid_pages_db(dbid);
520+
}
521+
522+
/*
523+
* Truncate a relation during XLOG replay
524+
*
525+
* We don't need to do anything to the fake relcache, but we do need to
526+
* clean up any open "invalid-page" records for the dropped pages.
527+
*/
528+
void
529+
XLogTruncateRelation(RelFileNodernode,BlockNumbernblocks)
530+
{
531+
forget_invalid_pages(rnode,nblocks);
341532
}

‎src/backend/storage/smgr/smgr.c‎

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,13 +11,14 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.98 2006/03/30 22:11:55 tgl Exp $
14+
* $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.99 2006/04/14 20:27:24 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
1818
#include"postgres.h"
1919

2020
#include"access/xact.h"
21+
#include"access/xlogutils.h"
2122
#include"commands/tablespace.h"
2223
#include"pgstat.h"
2324
#include"storage/bufmgr.h"
@@ -942,6 +943,9 @@ smgr_redo(XLogRecPtr lsn, XLogRecord *record)
942943
reln->smgr_rnode.dbNode,
943944
reln->smgr_rnode.relNode,
944945
xlrec->blkno)));
946+
947+
/* Also tell xlogutils.c about it */
948+
XLogTruncateRelation(xlrec->rnode,xlrec->blkno);
945949
}
946950
else
947951
elog(PANIC,"smgr_redo: unknown op code %u",info);

‎src/include/access/xlogutils.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/access/xlogutils.h,v 1.20 2006/03/29 21:17:39 tgl Exp $
9+
* $PostgreSQL: pgsql/src/include/access/xlogutils.h,v 1.21 2006/04/14 20:27:24 tgl Exp $
1010
*/
1111
#ifndefXLOG_UTILS_H
1212
#defineXLOG_UTILS_H
@@ -16,11 +16,13 @@
1616

1717

1818
externvoidXLogInitRelationCache(void);
19+
externvoidXLogCheckInvalidPages(void);
1920
externvoidXLogCloseRelationCache(void);
2021

2122
externRelationXLogOpenRelation(RelFileNodernode);
2223
externvoidXLogDropRelation(RelFileNodernode);
2324
externvoidXLogDropDatabase(Oiddbid);
25+
externvoidXLogTruncateRelation(RelFileNodernode,BlockNumbernblocks);
2426

2527
externBufferXLogReadBuffer(Relationreln,BlockNumberblkno,boolinit);
2628

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