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Commitb300527

Browse files
committed
Decouple the values of TOAST_TUPLE_THRESHOLD and TOAST_MAX_CHUNK_SIZE.
Add the latter to the values checked in pg_control, since it can't be changedwithout invalidating toast table content. This commit in itself shouldn'tchange any behavior, but it lays some necessary groundwork for experimentationwith these toast-control numbers.Note: while TOAST_TUPLE_THRESHOLD can now be changed without initdb, somethought still needs to be given to needs_toast_table() in toasting.c beforeunleashing random changes.
1 parent4fea0ca commitb300527

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8 files changed

+114
-48
lines changed

8 files changed

+114
-48
lines changed

‎doc/src/sgml/storage.sgml

Lines changed: 9 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.15 2007/03/02 00:48:44 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.16 2007/04/03 04:14:26 tgl Exp $ -->
22

33
<chapter id="storage">
44

@@ -240,8 +240,9 @@ of the LZ family of compression techniques. See
240240

241241
<para>
242242
Out-of-line values are divided (after compression if used) into chunks of at
243-
most <literal>TOAST_MAX_CHUNK_SIZE</> bytes (this value is a little less than
244-
<literal>BLCKSZ/4</>, or about 2000 bytes by default). Each chunk is stored
243+
most <symbol>TOAST_MAX_CHUNK_SIZE</> bytes (by default this value is chosen
244+
so that four chunk rows will fit on a page, making it about 2000 bytes).
245+
Each chunk is stored
245246
as a separate row in the <acronym>TOAST</> table for the owning table. Every
246247
<acronym>TOAST</> table has the columns <structfield>chunk_id</> (an OID
247248
identifying the particular <acronym>TOAST</>ed value),
@@ -260,10 +261,12 @@ regardless of the actual size of the represented value.
260261

261262
<para>
262263
The <acronym>TOAST</> code is triggered only
263-
when a row value to be stored in a table is wider than <literal>BLCKSZ/4</>
264-
bytes (normally 2 kB). The <acronym>TOAST</> code will compress and/or move
264+
when a row value to be stored in a table is wider than
265+
<symbol>TOAST_TUPLE_THRESHOLD</> bytes (normally 2 kB).
266+
The <acronym>TOAST</> code will compress and/or move
265267
field values out-of-line until the row value is shorter than
266-
<literal>BLCKSZ/4</> bytes or no more gains can be had. During an UPDATE
268+
<symbol>TOAST_TUPLE_TARGET</> bytes (also normally 2 kB)
269+
or no more gains can be had. During an UPDATE
267270
operation, values of unchanged fields are normally preserved as-is; so an
268271
UPDATE of a row with out-of-line values incurs no <acronym>TOAST</> costs if
269272
none of the out-of-line values change.

‎src/backend/access/heap/heapam.c

Lines changed: 25 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.230 2007/03/29 00:15:37 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.231 2007/04/03 04:14:26 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -1420,7 +1420,13 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
14201420
* Note: below this point, heaptup is the data we actually intend to store
14211421
* into the relation; tup is the caller's original untoasted data.
14221422
*/
1423-
if (HeapTupleHasExternal(tup)||tup->t_len>TOAST_TUPLE_THRESHOLD)
1423+
if (relation->rd_rel->relkind==RELKIND_TOASTVALUE)
1424+
{
1425+
/* toast table entries should never be recursively toasted */
1426+
Assert(!HeapTupleHasExternal(tup));
1427+
heaptup=tup;
1428+
}
1429+
elseif (HeapTupleHasExternal(tup)||tup->t_len>TOAST_TUPLE_THRESHOLD)
14241430
heaptup=toast_insert_or_update(relation,tup,NULL,
14251431
use_wal,use_fsm);
14261432
else
@@ -1777,7 +1783,12 @@ heap_delete(Relation relation, ItemPointer tid,
17771783
* because we need to look at the contents of the tuple, but it's OK to
17781784
* release the content lock on the buffer first.
17791785
*/
1780-
if (HeapTupleHasExternal(&tp))
1786+
if (relation->rd_rel->relkind==RELKIND_TOASTVALUE)
1787+
{
1788+
/* toast table entries should never be recursively toasted */
1789+
Assert(!HeapTupleHasExternal(&tp));
1790+
}
1791+
elseif (HeapTupleHasExternal(&tp))
17811792
toast_delete(relation,&tp);
17821793

17831794
/*
@@ -2075,9 +2086,17 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
20752086
* We need to invoke the toaster if there are already any out-of-line
20762087
* toasted values present, or if the new tuple is over-threshold.
20772088
*/
2078-
need_toast= (HeapTupleHasExternal(&oldtup)||
2079-
HeapTupleHasExternal(newtup)||
2080-
newtup->t_len>TOAST_TUPLE_THRESHOLD);
2089+
if (relation->rd_rel->relkind==RELKIND_TOASTVALUE)
2090+
{
2091+
/* toast table entries should never be recursively toasted */
2092+
Assert(!HeapTupleHasExternal(&oldtup));
2093+
Assert(!HeapTupleHasExternal(newtup));
2094+
need_toast= false;
2095+
}
2096+
else
2097+
need_toast= (HeapTupleHasExternal(&oldtup)||
2098+
HeapTupleHasExternal(newtup)||
2099+
newtup->t_len>TOAST_TUPLE_THRESHOLD);
20812100

20822101
pagefree=PageGetFreeSpace((Page)dp);
20832102

‎src/backend/access/heap/tuptoaster.c

Lines changed: 22 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.72 2007/03/29 00:15:37 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.73 2007/04/03 04:14:26 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -291,6 +291,12 @@ toast_delete(Relation rel, HeapTuple oldtup)
291291
Datumtoast_values[MaxHeapAttributeNumber];
292292
booltoast_isnull[MaxHeapAttributeNumber];
293293

294+
/*
295+
* We should only ever be called for tuples of plain relations ---
296+
* recursing on a toast rel is bad news.
297+
*/
298+
Assert(rel->rd_rel->relkind==RELKIND_RELATION);
299+
294300
/*
295301
* Get the tuple descriptor and break down the tuple into fields.
296302
*
@@ -360,6 +366,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
360366
boolhas_nulls= false;
361367

362368
SizemaxDataLen;
369+
Sizehoff;
363370

364371
chartoast_action[MaxHeapAttributeNumber];
365372
booltoast_isnull[MaxHeapAttributeNumber];
@@ -370,6 +377,12 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
370377
booltoast_free[MaxHeapAttributeNumber];
371378
booltoast_delold[MaxHeapAttributeNumber];
372379

380+
/*
381+
* We should only ever be called for tuples of plain relations ---
382+
* recursing on a toast rel is bad news.
383+
*/
384+
Assert(rel->rd_rel->relkind==RELKIND_RELATION);
385+
373386
/*
374387
* Get the tuple descriptor and break down the tuple(s) into fields.
375388
*/
@@ -512,15 +525,15 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
512525
*/
513526

514527
/* compute header overhead --- this should match heap_form_tuple() */
515-
maxDataLen= offsetof(HeapTupleHeaderData,t_bits);
528+
hoff= offsetof(HeapTupleHeaderData,t_bits);
516529
if (has_nulls)
517-
maxDataLen+=BITMAPLEN(numAttrs);
530+
hoff+=BITMAPLEN(numAttrs);
518531
if (newtup->t_data->t_infomask&HEAP_HASOID)
519-
maxDataLen+=sizeof(Oid);
520-
maxDataLen=MAXALIGN(maxDataLen);
521-
Assert(maxDataLen==newtup->t_data->t_hoff);
532+
hoff+=sizeof(Oid);
533+
hoff=MAXALIGN(hoff);
534+
Assert(hoff==newtup->t_data->t_hoff);
522535
/* now convert to a limit on the tuple data size */
523-
maxDataLen=TOAST_TUPLE_TARGET-maxDataLen;
536+
maxDataLen=TOAST_TUPLE_TARGET-hoff;
524537

525538
/*
526539
* Look for attributes with attstorage 'x' to compress
@@ -583,7 +596,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
583596

584597
/*
585598
* Second we look for attributes of attstorage 'x' or 'e' that are still
586-
* inline.
599+
* inline. But skip this if there's no toast table to push them to.
587600
*/
588601
while (heap_compute_data_size(tupleDesc,
589602
toast_values,toast_isnull)>maxDataLen&&
@@ -695,7 +708,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
695708
}
696709

697710
/*
698-
* Finally we store attributes of type 'm' external
711+
* Finally we store attributes of type 'm' external, if possible.
699712
*/
700713
while (heap_compute_data_size(tupleDesc,
701714
toast_values,toast_isnull)>maxDataLen&&

‎src/backend/access/transam/xlog.c

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2007, 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 1.265 2007/03/0320:02:26momjian Exp $
10+
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.266 2007/04/0304:14:26tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -28,6 +28,7 @@
2828
#include"access/multixact.h"
2929
#include"access/subtrans.h"
3030
#include"access/transam.h"
31+
#include"access/tuptoaster.h"
3132
#include"access/twophase.h"
3233
#include"access/xact.h"
3334
#include"access/xlog_internal.h"
@@ -3634,6 +3635,8 @@ WriteControlFile(void)
36343635
ControlFile->nameDataLen=NAMEDATALEN;
36353636
ControlFile->indexMaxKeys=INDEX_MAX_KEYS;
36363637

3638+
ControlFile->toast_max_chunk_size=TOAST_MAX_CHUNK_SIZE;
3639+
36373640
#ifdefHAVE_INT64_TIMESTAMP
36383641
ControlFile->enableIntTimes= TRUE;
36393642
#else
@@ -3824,6 +3827,13 @@ ReadControlFile(void)
38243827
" but the server was compiled with INDEX_MAX_KEYS %d.",
38253828
ControlFile->indexMaxKeys,INDEX_MAX_KEYS),
38263829
errhint("It looks like you need to recompile or initdb.")));
3830+
if (ControlFile->toast_max_chunk_size!=TOAST_MAX_CHUNK_SIZE)
3831+
ereport(FATAL,
3832+
(errmsg("database files are incompatible with server"),
3833+
errdetail("The database cluster was initialized with TOAST_MAX_CHUNK_SIZE %d,"
3834+
" but the server was compiled with TOAST_MAX_CHUNK_SIZE %d.",
3835+
ControlFile->toast_max_chunk_size, (int)TOAST_MAX_CHUNK_SIZE),
3836+
errhint("It looks like you need to recompile or initdb.")));
38273837

38283838
#ifdefHAVE_INT64_TIMESTAMP
38293839
if (ControlFile->enableIntTimes!= TRUE)

‎src/bin/pg_controldata/pg_controldata.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* copyright (c) Oliver Elphick <olly@lfix.co.uk>, 2001;
77
* licence: BSD
88
*
9-
* $PostgreSQL: pgsql/src/bin/pg_controldata/pg_controldata.c,v 1.34 2007/03/18 16:50:43 neilc Exp $
9+
* $PostgreSQL: pgsql/src/bin/pg_controldata/pg_controldata.c,v 1.35 2007/04/03 04:14:26 tgl Exp $
1010
*/
1111
#include"postgres.h"
1212

@@ -199,6 +199,8 @@ main(int argc, char *argv[])
199199
ControlFile.nameDataLen);
200200
printf(_("Maximum columns in an index: %u\n"),
201201
ControlFile.indexMaxKeys);
202+
printf(_("Maximum size of a TOAST chunk: %u\n"),
203+
ControlFile.toast_max_chunk_size);
202204
printf(_("Date/time type storage: %s\n"),
203205
(ControlFile.enableIntTimes ?_("64-bit integers") :_("floating-point numbers")));
204206
printf(_("Maximum length of locale name: %u\n"),

‎src/bin/pg_resetxlog/pg_resetxlog.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@
2323
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
2424
* Portions Copyright (c) 1994, Regents of the University of California
2525
*
26-
* $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.58 2007/03/0320:02:27 momjian Exp $
26+
* $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.59 2007/04/0304:14:26 tgl Exp $
2727
*
2828
*-------------------------------------------------------------------------
2929
*/
@@ -41,6 +41,7 @@
4141
#endif
4242

4343
#include"access/transam.h"
44+
#include"access/tuptoaster.h"
4445
#include"access/multixact.h"
4546
#include"access/xlog_internal.h"
4647
#include"catalog/catversion.h"
@@ -484,6 +485,7 @@ GuessControlValues(void)
484485
ControlFile.xlog_seg_size=XLOG_SEG_SIZE;
485486
ControlFile.nameDataLen=NAMEDATALEN;
486487
ControlFile.indexMaxKeys=INDEX_MAX_KEYS;
488+
ControlFile.toast_max_chunk_size=TOAST_MAX_CHUNK_SIZE;
487489
#ifdefHAVE_INT64_TIMESTAMP
488490
ControlFile.enableIntTimes= TRUE;
489491
#else
@@ -572,6 +574,8 @@ PrintControlValues(bool guessed)
572574
ControlFile.nameDataLen);
573575
printf(_("Maximum columns in an index: %u\n"),
574576
ControlFile.indexMaxKeys);
577+
printf(_("Maximum size of a TOAST chunk: %u\n"),
578+
ControlFile.toast_max_chunk_size);
575579
printf(_("Date/time type storage: %s\n"),
576580
(ControlFile.enableIntTimes ?_("64-bit integers") :_("floating-point numbers")));
577581
printf(_("Maximum length of locale name: %u\n"),

‎src/include/access/tuptoaster.h

Lines changed: 35 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 2000-2007, PostgreSQL Global Development Group
88
*
9-
* $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.33 2007/03/29 00:15:39 tgl Exp $
9+
* $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.34 2007/04/03 04:14:26 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -29,19 +29,26 @@
2929
* TOAST_TUPLE_TARGET bytes. Both numbers include all tuple header overhead
3030
* and between-fields alignment padding, but we do *not* consider any
3131
* end-of-tuple alignment padding; hence the values can be compared directly
32-
* to a tuple's t_len field. We choose TOAST_TUPLE_THRESHOLD with the
33-
* knowledge that toast-table tuples will be exactly that size, and we'd
34-
* like to fit four of them per page with minimal space wastage.
32+
* to a tuple's t_len field.
3533
*
36-
* The numbers need not be the same, though they currently are.
34+
* The numbers need not be the same, though they currently are. It doesn't
35+
* make sense for TARGET to exceed THRESHOLD, but it could be useful to make
36+
* it be smaller.
3737
*
38-
* Note: sizeof(PageHeaderData) includes the first ItemId, but we have
39-
* to allow for 3 more, if we want to fit 4 tuples on a page.
38+
* Currently we choose both values to match the largest tuple size for which
39+
* TOAST_TUPLES_PER_PAGE tuples can fit on a disk page.
40+
*
41+
* XXX while these can be modified without initdb, some thought needs to be
42+
* given to needs_toast_table() in toasting.c before unleashing random
43+
* changes.
4044
*/
45+
#defineTOAST_TUPLES_PER_PAGE4
46+
47+
/* Note: sizeof(PageHeaderData) includes the first ItemId on the page */
4148
#defineTOAST_TUPLE_THRESHOLD\
4249
MAXALIGN_DOWN((BLCKSZ - \
43-
MAXALIGN(sizeof(PageHeaderData) +3 * sizeof(ItemIdData))) \
44-
/4)
50+
MAXALIGN(sizeof(PageHeaderData) +(TOAST_TUPLES_PER_PAGE-1) * sizeof(ItemIdData))) \
51+
/TOAST_TUPLES_PER_PAGE)
4552

4653
#defineTOAST_TUPLE_TARGETTOAST_TUPLE_THRESHOLD
4754

@@ -56,20 +63,26 @@
5663
* When we store an oversize datum externally, we divide it into chunks
5764
* containing at most TOAST_MAX_CHUNK_SIZE data bytes.This number *must*
5865
* be small enough that the completed toast-table tuple (including the
59-
* ID and sequence fields and all overhead) is no more than MaxHeapTupleSize
60-
* bytes. It *should* be small enough to make toast-table tuples no more
61-
* than TOAST_TUPLE_THRESHOLD bytes, else heapam.c will uselessly invoke
62-
* the toaster on toast-table tuples. The current coding ensures that the
63-
* maximum tuple length is exactly TOAST_TUPLE_THRESHOLD bytes.
64-
*
65-
* NB: you cannot change this value without forcing initdb, at least not
66-
* if your DB contains any multi-chunk toasted values.
66+
* ID and sequence fields and all overhead) will fit on a page.
67+
* The coding here sets the size on the theory that we want to fit
68+
* EXTERN_TUPLES_PER_PAGE tuples of maximum size onto a page.
69+
*
70+
* NB: Changing TOAST_MAX_CHUNK_SIZE requires an initdb.
6771
*/
68-
#defineTOAST_MAX_CHUNK_SIZE(TOAST_TUPLE_THRESHOLD -\
69-
MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) -\
70-
sizeof(Oid) -\
71-
sizeof(int32) -\
72-
VARHDRSZ)
72+
#defineEXTERN_TUPLES_PER_PAGE4/* tweak only this */
73+
74+
/* Note: sizeof(PageHeaderData) includes the first ItemId on the page */
75+
#defineEXTERN_TUPLE_MAX_SIZE\
76+
MAXALIGN_DOWN((BLCKSZ - \
77+
MAXALIGN(sizeof(PageHeaderData) + (EXTERN_TUPLES_PER_PAGE-1) * sizeof(ItemIdData))) \
78+
/ EXTERN_TUPLES_PER_PAGE)
79+
80+
#defineTOAST_MAX_CHUNK_SIZE\
81+
(EXTERN_TUPLE_MAX_SIZE -\
82+
MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) -\
83+
sizeof(Oid) -\
84+
sizeof(int32) -\
85+
VARHDRSZ)
7386

7487

7588
/* ----------

‎src/include/catalog/pg_control.h

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $PostgreSQL: pgsql/src/include/catalog/pg_control.h,v 1.36 2007/03/0320:02:27 momjian Exp $
11+
* $PostgreSQL: pgsql/src/include/catalog/pg_control.h,v 1.37 2007/04/0304:14:26 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -22,7 +22,7 @@
2222

2323

2424
/* Version identifier for this pg_control format */
25-
#definePG_CONTROL_VERSION832
25+
#definePG_CONTROL_VERSION833
2626

2727
/*
2828
* Body of CheckPoint XLOG records. This is declared here because we keep
@@ -135,6 +135,8 @@ typedef struct ControlFileData
135135
uint32nameDataLen;/* catalog name field width */
136136
uint32indexMaxKeys;/* max number of columns in an index */
137137

138+
uint32toast_max_chunk_size;/* chunk size in TOAST tables */
139+
138140
/* flag indicating internal format of timestamp, interval, time */
139141
uint32enableIntTimes;/* int64 storage enabled? */
140142

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