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Commit059e361

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Although we can't support out-of-line TOAST storage in indexes (yet),
compressed storage works perfectly well. Might as well have a coherentstrategy for applying it, rather than the haphazard store-what-you-getapproach that was in the code before. The strategy I've set up here isto attempt compression of any compressible index value exceedingBLCKSZ/16, or about 500 bytes by default.
1 parent5341cdd commit059e361

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3 files changed

+54
-22
lines changed

3 files changed

+54
-22
lines changed

‎src/backend/access/common/indextuple.c‎

Lines changed: 37 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -2,14 +2,14 @@
22
*
33
* indextuple.c
44
* This file contains index tuple accessor and mutator routines,
5-
* as well asa fewvarious tuple utilities.
5+
* as well as various tuple utilities.
66
*
77
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
*
1111
* IDENTIFICATION
12-
* $Header: /cvsroot/pgsql/src/backend/access/common/indextuple.c,v 1.50 2001/01/24 19:42:47 momjian Exp $
12+
* $Header: /cvsroot/pgsql/src/backend/access/common/indextuple.c,v 1.51 2001/02/15 20:57:01 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -57,25 +57,45 @@ index_formtuple(TupleDesc tupleDescriptor,
5757
#ifdefTOAST_INDEX_HACK
5858
for (i=0;i<numberOfAttributes;i++)
5959
{
60-
if (null[i]!=' '||tupleDescriptor->attrs[i]->attlen >=0)
60+
Form_pg_attributeatt=tupleDescriptor->attrs[i];
61+
62+
untoasted_value[i]=value[i];
63+
untoasted_free[i]= false;
64+
65+
/* Do nothing if value is NULL or not of varlena type */
66+
if (null[i]!=' '||att->attlen >=0)
67+
continue;
68+
69+
/*
70+
* If value is stored EXTERNAL, must fetch it so we are not
71+
* depending on outside storage. This should be improved someday.
72+
*/
73+
if (VARATT_IS_EXTERNAL(value[i]))
6174
{
62-
untoasted_value[i]=value[i];
63-
untoasted_free[i]= false;
75+
untoasted_value[i]=PointerGetDatum(
76+
heap_tuple_fetch_attr(
77+
(varattrib*)DatumGetPointer(value[i])));
78+
untoasted_free[i]= true;
6479
}
65-
else
80+
81+
/*
82+
* If value is above size target, and is of a compressible datatype,
83+
* try to compress it in-line.
84+
*/
85+
if (VARATT_SIZE(untoasted_value[i])>TOAST_INDEX_TARGET&&
86+
!VARATT_IS_EXTENDED(untoasted_value[i])&&
87+
(att->attstorage=='x'||att->attstorage=='m'))
6688
{
67-
if (VARATT_IS_EXTERNAL(value[i]))
89+
Datumcvalue=toast_compress_datum(untoasted_value[i]);
90+
91+
if (DatumGetPointer(cvalue)!=NULL)
6892
{
69-
untoasted_value[i]=PointerGetDatum(
70-
heap_tuple_fetch_attr(
71-
(varattrib*)DatumGetPointer(value[i])));
93+
/* successful compression */
94+
if (untoasted_free[i])
95+
pfree(DatumGetPointer(untoasted_value[i]));
96+
untoasted_value[i]=cvalue;
7297
untoasted_free[i]= true;
7398
}
74-
else
75-
{
76-
untoasted_value[i]=value[i];
77-
untoasted_free[i]= false;
78-
}
7999
}
80100
}
81101
#endif
@@ -137,10 +157,9 @@ index_formtuple(TupleDesc tupleDescriptor,
137157
* Here we make sure that the size will fit in the field reserved for
138158
* it in t_info.
139159
*/
140-
141160
if ((size&INDEX_SIZE_MASK)!=size)
142-
elog(ERROR,"index_formtuple: data takes %lu bytes: too big",
143-
(unsigned long)size);
161+
elog(ERROR,"index_formtuple: data takes %lu bytes, max is %d",
162+
(unsigned long)size,INDEX_SIZE_MASK);
144163

145164
infomask |=size;
146165

‎src/backend/access/heap/tuptoaster.c‎

Lines changed: 2 additions & 3 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 1.16 2001/02/09 17:30:03 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.17 2001/02/15 20:57:01 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -45,7 +45,6 @@ static voidtoast_delete(Relation rel, HeapTuple oldtup);
4545
staticvoidtoast_delete_datum(Relationrel,Datumvalue);
4646
staticvoidtoast_insert_or_update(Relationrel,HeapTuplenewtup,
4747
HeapTupleoldtup);
48-
staticDatumtoast_compress_datum(Datumvalue);
4948
staticDatumtoast_save_datum(Relationrel,Oidmainoid,int16attno,Datumvalue);
5049
staticvarattrib*toast_fetch_datum(varattrib*attr);
5150

@@ -721,7 +720,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup)
721720
*the tuple!
722721
* ----------
723722
*/
724-
staticDatum
723+
Datum
725724
toast_compress_datum(Datumvalue)
726725
{
727726
varattrib*tmp;

‎src/include/access/tuptoaster.h‎

Lines changed: 15 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 2000, PostgreSQL Development Team
88
*
9-
* $Id: tuptoaster.h,v 1.8 2000/08/04 04:16:10 tgl Exp $
9+
* $Id: tuptoaster.h,v 1.9 2001/02/15 20:57:01 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -40,6 +40,12 @@
4040

4141
#defineTOAST_TUPLE_TARGET(MaxTupleSize / 4)
4242

43+
/*
44+
* If an index value is larger than TOAST_INDEX_TARGET, we will try to
45+
* compress it (we can't move it out-of-line, however). Note that this
46+
* number is per-datum, not per-tuple, for simplicity in index_formtuple().
47+
*/
48+
#defineTOAST_INDEX_TARGET(MaxTupleSize / 16)
4349

4450
/*
4551
* When we store an oversize datum externally, we divide it into chunks
@@ -95,6 +101,14 @@ extern varattrib *heap_tuple_fetch_attr(varattrib * attr);
95101
*/
96102
externvarattrib*heap_tuple_untoast_attr(varattrib*attr);
97103

104+
/* ----------
105+
* toast_compress_datum -
106+
*
107+
*Create a compressed version of a varlena datum, if possible
108+
* ----------
109+
*/
110+
externDatumtoast_compress_datum(Datumvalue);
111+
98112
#endif/* TUPLE_TOASTER_ACTIVE */
99113

100114

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