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Commit3212cf9

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Distinguish between MaxHeapAttributeNumber and MaxTupleAttributeNumber,
where the latter is made slightly larger to allow for in-memory tuplescontaining resjunk attributes. Responds to today's complaint that onecannot UPDATE a table containing the allegedly-legal maximum number ofcolumns.Also, apply Manfred Koizar's recent patch to avoid extra alignment paddingwhen there is a null bitmap. This saves bytes in some cases while notcreating any backward-compatibility problem AFAICS.
1 parent3cde085 commit3212cf9

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3 files changed

+63
-61
lines changed

3 files changed

+63
-61
lines changed

‎src/backend/access/common/heaptuple.c‎

Lines changed: 9 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.74 2001/10/25 05:49:20 momjian Exp $
12+
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.75 2002/05/27 19:53:33 tgl Exp $
1313
*
1414
* NOTES
1515
* The old interface functions have been converted to macros
@@ -571,18 +571,15 @@ heap_formtuple(TupleDesc tupleDescriptor,
571571
{
572572
HeapTupletuple;/* return tuple */
573573
HeapTupleHeadertd;/* tuple data */
574-
intbitmaplen;
575574
unsigned longlen;
576575
inthoff;
577576
boolhasnull= false;
578577
inti;
579578
intnumberOfAttributes=tupleDescriptor->natts;
580579

581-
if (numberOfAttributes>MaxHeapAttributeNumber)
582-
elog(ERROR,"heap_formtuple: numberOfAttributes of %d > %d",
583-
numberOfAttributes,MaxHeapAttributeNumber);
584-
585-
len= offsetof(HeapTupleHeaderData,t_bits);
580+
if (numberOfAttributes>MaxTupleAttributeNumber)
581+
elog(ERROR,"heap_formtuple: numberOfAttributes %d exceeds limit %d",
582+
numberOfAttributes,MaxTupleAttributeNumber);
586583

587584
for (i=0;i<numberOfAttributes;i++)
588585
{
@@ -593,13 +590,12 @@ heap_formtuple(TupleDesc tupleDescriptor,
593590
}
594591
}
595592

593+
len= offsetof(HeapTupleHeaderData,t_bits);
594+
596595
if (hasnull)
597-
{
598-
bitmaplen=BITMAPLEN(numberOfAttributes);
599-
len+=bitmaplen;
600-
}
596+
len+=BITMAPLEN(numberOfAttributes);
601597

602-
hoff=len=MAXALIGN(len);/*be conservative here */
598+
hoff=len=MAXALIGN(len);/*align user data safely */
603599

604600
len+=ComputeDataSize(tupleDescriptor,value,nulls);
605601

@@ -615,7 +611,7 @@ heap_formtuple(TupleDesc tupleDescriptor,
615611
td->t_natts=numberOfAttributes;
616612
td->t_hoff=hoff;
617613

618-
DataFill((char*)td+td->t_hoff,
614+
DataFill((char*)td+hoff,
619615
tupleDescriptor,
620616
value,
621617
nulls,

‎src/backend/access/heap/tuptoaster.c‎

Lines changed: 11 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.31 2002/05/24 18:57:55 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.32 2002/05/27 19:53:33 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -715,39 +715,34 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup)
715715
*/
716716
if (need_change)
717717
{
718+
HeapTupleHeaderolddata=newtup->t_data;
718719
char*new_data;
719720
int32new_len;
720-
MemoryContextoldcxt;
721-
HeapTupleHeaderolddata;
722721

723722
/*
724-
* Calculate the new size of the tuple
723+
* Calculate the new size of the tuple. Header size should not
724+
* change, but data size might.
725725
*/
726726
new_len= offsetof(HeapTupleHeaderData,t_bits);
727727
if (has_nulls)
728728
new_len+=BITMAPLEN(numAttrs);
729729
new_len=MAXALIGN(new_len);
730+
Assert(new_len==olddata->t_hoff);
730731
new_len+=ComputeDataSize(tupleDesc,toast_values,toast_nulls);
731732

732733
/*
733-
* Remember the old memory location of the tuple (for below),
734-
* switch to the memory context of the HeapTuple structure and
735-
* allocate the new tuple.
734+
* Allocate new tuple in same context as old one.
736735
*/
737-
olddata=newtup->t_data;
738-
oldcxt=MemoryContextSwitchTo(newtup->t_datamcxt);
739-
new_data=palloc(new_len);
736+
new_data=(char*)MemoryContextAlloc(newtup->t_datamcxt,new_len);
737+
newtup->t_data=(HeapTupleHeader)new_data;
738+
newtup->t_len=new_len;
740739

741740
/*
742741
* Put the tuple header and the changed values into place
743742
*/
744-
memcpy(new_data,newtup->t_data,newtup->t_data->t_hoff);
745-
newtup->t_data= (HeapTupleHeader)new_data;
746-
newtup->t_len=new_len;
743+
memcpy(new_data,olddata,olddata->t_hoff);
747744

748-
DataFill((char*) (MAXALIGN((long)new_data+
749-
offsetof(HeapTupleHeaderData,t_bits)+
750-
((has_nulls) ?BITMAPLEN(numAttrs) :0))),
745+
DataFill((char*)new_data+olddata->t_hoff,
751746
tupleDesc,
752747
toast_values,
753748
toast_nulls,
@@ -760,11 +755,6 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup)
760755
*/
761756
if ((char*)olddata!= ((char*)newtup+HEAPTUPLESIZE))
762757
pfree(olddata);
763-
764-
/*
765-
* Switch back to the old memory context
766-
*/
767-
MemoryContextSwitchTo(oldcxt);
768758
}
769759

770760
/*

‎src/include/access/htup.h‎

Lines changed: 43 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id: htup.h,v 1.51 2001/11/05 17:46:31 momjian Exp $
10+
* $Id: htup.h,v 1.52 2002/05/27 19:53:33 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -17,25 +17,44 @@
1717
#include"storage/bufpage.h"
1818
#include"storage/relfilenode.h"
1919

20-
#defineMinHeapTupleBitmapSize32/* 8 * 4 */
2120

2221
/*
23-
*MaxHeapAttributeNumber limits the number of (user) columns in atable.
22+
*MaxTupleAttributeNumber limits the number of (user) columns in atuple.
2423
* The key limit on this value is that the size of the fixed overhead for
2524
* a tuple, plus the size of the null-values bitmap (at 1 bit per column),
2625
* plus MAXALIGN alignment, must fit into t_hoff which is uint8. On most
27-
* machines the absolute upper limit without making t_hoff wider would be
28-
* about 1700.Note, however, that depending on column data types you will
29-
* likely also be running into the disk-block-based limit on overall tuple
30-
* size if you have more than a thousand or so columns. TOAST won't help.
26+
* machines the upper limit without making t_hoff wider would be a little
27+
* over 1700. We use round numbers here and for MaxHeapAttributeNumber
28+
* so that alterations in HeapTupleHeaderData layout won't change the
29+
* supported max number of columns.
30+
*/
31+
#defineMaxTupleAttributeNumber1664/* 8 * 208 */
32+
33+
/*----------
34+
* MaxHeapAttributeNumber limits the number of (user) columns in a table.
35+
* This should be somewhat less than MaxTupleAttributeNumber. It must be
36+
* at least one less, else we will fail to do UPDATEs on a maximal-width
37+
* table (because UPDATE has to form working tuples that include CTID).
38+
* In practice we want some additional daylight so that we can gracefully
39+
* support operations that add hidden "resjunk" columns, for example
40+
* SELECT * FROM wide_table ORDER BY foo, bar, baz.
41+
* In any case, depending on column data types you will likely be running
42+
* into the disk-block-based limit on overall tuple size if you have more
43+
* than a thousand or so columns. TOAST won't help.
44+
*----------
3145
*/
3246
#defineMaxHeapAttributeNumber1600/* 8 * 200 */
3347

3448
/*
35-
* This is the on-disk copy of the tuple.
49+
* On-disk heap tuple header. Currently this is also used as the header
50+
* format for tuples formed in memory, although in principle they could
51+
* be different.
3652
*
3753
* To avoid wasting space, the attributes should be layed out in such a
38-
* way to reduce structure padding.
54+
* way to reduce structure padding. Note that t_hoff is the offset to
55+
* the start of the user data, and so must be a multiple of MAXALIGN.
56+
* Also note that we omit the nulls bitmap if t_infomask shows that there
57+
* are no nulls in the tuple.
3958
*/
4059
typedefstructHeapTupleHeaderData
4160
{
@@ -51,14 +70,13 @@ typedef struct HeapTupleHeaderData
5170

5271
int16t_natts;/* number of attributes */
5372

54-
uint16t_infomask;/* variousinfos */
73+
uint16t_infomask;/* variousflag bits, see below */
5574

56-
uint8t_hoff;/* sizeof() tupleheader */
75+
uint8t_hoff;/* sizeofheader incl. bitmap, padding */
5776

5877
/* ^ - 31 bytes - ^ */
5978

60-
bits8t_bits[MinHeapTupleBitmapSize /8];
61-
/* bit map of NULLs */
79+
bits8t_bits[1];/* bitmap of NULLs -- VARIABLE LENGTH */
6280

6381
/* MORE DATA FOLLOWS AT END OF STRUCT */
6482
}HeapTupleHeaderData;
@@ -183,7 +201,7 @@ typedef struct xl_heap_clean
183201
#defineFirstLowInvalidHeapAttributeNumber(-8)
184202

185203
/*
186-
*This isthe in-memorycopy of the tuple.
204+
*HeapTupleData isan in-memorydata structure that points to a tuple.
187205
*
188206
* This new HeapTuple for version >= 6.5 and this is why it was changed:
189207
*
@@ -222,11 +240,9 @@ typedef HeapTupleData *HeapTuple;
222240

223241
/*
224242
* BITMAPLEN(NATTS) -
225-
*Computesminimumsize of bitmap given number ofdomains.
243+
*Computes size ofnullbitmap given number ofdata columns.
226244
*/
227-
#defineBITMAPLEN(NATTS) \
228-
((((((int)(NATTS) - 1) >> 3) + 4 - (MinHeapTupleBitmapSize >> 3)) \
229-
& ~03) + (MinHeapTupleBitmapSize >> 3))
245+
#defineBITMAPLEN(NATTS)(((int)(NATTS) + 7) / 8)
230246

231247
/*
232248
* HeapTupleIsValid
@@ -240,26 +256,26 @@ typedef HeapTupleData *HeapTuple;
240256
#defineHEAP_HASNULL0x0001/* has null attribute(s) */
241257
#defineHEAP_HASVARLENA0x0002/* has variable length
242258
* attribute(s) */
243-
#defineHEAP_HASEXTERNAL0x0004/* has external stored */
244-
/* attribute(s) */
245-
#defineHEAP_HASCOMPRESSED0x0008/* has compressed stored */
246-
/* attribute(s) */
259+
#defineHEAP_HASEXTERNAL0x0004/* has external stored
260+
* attribute(s) */
261+
#defineHEAP_HASCOMPRESSED0x0008/* has compressed stored
262+
* attribute(s) */
247263
#defineHEAP_HASEXTENDED0x000C/* the two above combined */
248264

249-
#defineHEAP_XMAX_UNLOGGED0x0080/* to lock tuple for update */
250-
/* without logging */
265+
#defineHEAP_XMAX_UNLOGGED0x0080/* to lock tuple for update
266+
* without logging */
251267
#defineHEAP_XMIN_COMMITTED0x0100/* t_xmin committed */
252268
#defineHEAP_XMIN_INVALID0x0200/* t_xmin invalid/aborted */
253269
#defineHEAP_XMAX_COMMITTED0x0400/* t_xmax committed */
254270
#defineHEAP_XMAX_INVALID0x0800/* t_xmax invalid/aborted */
255271
#defineHEAP_MARKED_FOR_UPDATE0x1000/* marked for UPDATE */
256272
#defineHEAP_UPDATED0x2000/* this is UPDATEd version of row */
257-
#defineHEAP_MOVED_OFF0x4000/*removed ormoved to another
258-
*place byvacuum */
273+
#defineHEAP_MOVED_OFF0x4000/* moved to another place by
274+
* vacuum */
259275
#defineHEAP_MOVED_IN0x8000/* moved from another place by
260276
* vacuum */
261277

262-
#defineHEAP_XACT_MASK0xFFF0/* */
278+
#defineHEAP_XACT_MASK0xFFF0/*visibility-related bits*/
263279

264280
#defineHeapTupleNoNulls(tuple) \
265281
(!(((HeapTuple) (tuple))->t_data->t_infomask & HEAP_HASNULL))

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