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Commit1171d7d

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tableam: Move heap-specific logic from needs_toast_table below tableam.
This allows table AMs to completely suppress TOAST table creation, orto modify the conditions under which they are created.Patch by me. Reviewed by Andres Freund.Discussion:http://postgr.es/m/CA+Tgmoa4O2n=yphqD2pERUnYmUO84bH1SqMsA-nSxBGsZ7gWfA@mail.gmail.com
1 parentcf92226 commit1171d7d

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3 files changed

+76
-47
lines changed

3 files changed

+76
-47
lines changed

‎src/backend/access/heap/heapam_handler.c‎

Lines changed: 53 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@
2929
#include"access/rewriteheap.h"
3030
#include"access/tableam.h"
3131
#include"access/tsmapi.h"
32+
#include"access/tuptoaster.h"
3233
#include"access/xact.h"
3334
#include"catalog/catalog.h"
3435
#include"catalog/index.h"
@@ -2009,6 +2010,57 @@ heapam_relation_size(Relation rel, ForkNumber forkNumber)
20092010
returnnblocks*BLCKSZ;
20102011
}
20112012

2013+
/*
2014+
* Check to see whether the table needs a TOAST table. It does only if
2015+
* (1) there are any toastable attributes, and (2) the maximum length
2016+
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
2017+
* create a toast table for something like "f1 varchar(20)".)
2018+
*/
2019+
staticbool
2020+
heapam_relation_needs_toast_table(Relationrel)
2021+
{
2022+
int32data_length=0;
2023+
boolmaxlength_unknown= false;
2024+
boolhas_toastable_attrs= false;
2025+
TupleDesctupdesc=rel->rd_att;
2026+
int32tuple_length;
2027+
inti;
2028+
2029+
for (i=0;i<tupdesc->natts;i++)
2030+
{
2031+
Form_pg_attributeatt=TupleDescAttr(tupdesc,i);
2032+
2033+
if (att->attisdropped)
2034+
continue;
2035+
data_length=att_align_nominal(data_length,att->attalign);
2036+
if (att->attlen>0)
2037+
{
2038+
/* Fixed-length types are never toastable */
2039+
data_length+=att->attlen;
2040+
}
2041+
else
2042+
{
2043+
int32maxlen=type_maximum_size(att->atttypid,
2044+
att->atttypmod);
2045+
2046+
if (maxlen<0)
2047+
maxlength_unknown= true;
2048+
else
2049+
data_length+=maxlen;
2050+
if (att->attstorage!='p')
2051+
has_toastable_attrs= true;
2052+
}
2053+
}
2054+
if (!has_toastable_attrs)
2055+
return false;/* nothing to toast? */
2056+
if (maxlength_unknown)
2057+
return true;/* any unlimited-length attrs? */
2058+
tuple_length=MAXALIGN(SizeofHeapTupleHeader+
2059+
BITMAPLEN(tupdesc->natts))+
2060+
MAXALIGN(data_length);
2061+
return (tuple_length>TOAST_TUPLE_THRESHOLD);
2062+
}
2063+
20122064

20132065
/* ------------------------------------------------------------------------
20142066
* Planner related callbacks for the heap AM
@@ -2592,6 +2644,7 @@ static const TableAmRoutine heapam_methods = {
25922644
.index_validate_scan=heapam_index_validate_scan,
25932645

25942646
.relation_size=heapam_relation_size,
2647+
.relation_needs_toast_table=heapam_relation_needs_toast_table,
25952648

25962649
.relation_estimate_size=heapam_estimate_rel_size,
25972650

‎src/backend/catalog/toasting.c‎

Lines changed: 3 additions & 47 deletions
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,6 @@
1515
#include"postgres.h"
1616

1717
#include"access/heapam.h"
18-
#include"access/tuptoaster.h"
1918
#include"access/xact.h"
2019
#include"catalog/binary_upgrade.h"
2120
#include"catalog/catalog.h"
@@ -386,21 +385,11 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
386385
}
387386

388387
/*
389-
* Check to see whether the table needs a TOAST table. It does only if
390-
* (1) there are any toastable attributes, and (2) the maximum length
391-
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
392-
* create a toast table for something like "f1 varchar(20)".)
388+
* Check to see whether the table needs a TOAST table.
393389
*/
394390
staticbool
395391
needs_toast_table(Relationrel)
396392
{
397-
int32data_length=0;
398-
boolmaxlength_unknown= false;
399-
boolhas_toastable_attrs= false;
400-
TupleDesctupdesc;
401-
int32tuple_length;
402-
inti;
403-
404393
/*
405394
* No need to create a TOAST table for partitioned tables.
406395
*/
@@ -423,39 +412,6 @@ needs_toast_table(Relation rel)
423412
if (IsCatalogRelation(rel)&& !IsBootstrapProcessingMode())
424413
return false;
425414

426-
tupdesc=rel->rd_att;
427-
428-
for (i=0;i<tupdesc->natts;i++)
429-
{
430-
Form_pg_attributeatt=TupleDescAttr(tupdesc,i);
431-
432-
if (att->attisdropped)
433-
continue;
434-
data_length=att_align_nominal(data_length,att->attalign);
435-
if (att->attlen>0)
436-
{
437-
/* Fixed-length types are never toastable */
438-
data_length+=att->attlen;
439-
}
440-
else
441-
{
442-
int32maxlen=type_maximum_size(att->atttypid,
443-
att->atttypmod);
444-
445-
if (maxlen<0)
446-
maxlength_unknown= true;
447-
else
448-
data_length+=maxlen;
449-
if (att->attstorage!='p')
450-
has_toastable_attrs= true;
451-
}
452-
}
453-
if (!has_toastable_attrs)
454-
return false;/* nothing to toast? */
455-
if (maxlength_unknown)
456-
return true;/* any unlimited-length attrs? */
457-
tuple_length=MAXALIGN(SizeofHeapTupleHeader+
458-
BITMAPLEN(tupdesc->natts))+
459-
MAXALIGN(data_length);
460-
return (tuple_length>TOAST_TUPLE_THRESHOLD);
415+
/* Otherwise, let the AM decide. */
416+
returntable_relation_needs_toast_table(rel);
461417
}

‎src/include/access/tableam.h‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -573,6 +573,16 @@ typedef struct TableAmRoutine
573573
uint64(*relation_size) (Relationrel,ForkNumberforkNumber);
574574

575575

576+
/*
577+
* This callback should return true if the relation requires a TOAST table
578+
* and false if it does not. It may wish to examine the relation's
579+
* tuple descriptor before making a decision, but if it uses some other
580+
* method of storing large values (or if it does not support them) it can
581+
* simply return false.
582+
*/
583+
bool (*relation_needs_toast_table) (Relationrel);
584+
585+
576586
/* ------------------------------------------------------------------------
577587
* Planner related functions.
578588
* ------------------------------------------------------------------------
@@ -1585,6 +1595,16 @@ table_relation_size(Relation rel, ForkNumber forkNumber)
15851595
returnrel->rd_tableam->relation_size(rel,forkNumber);
15861596
}
15871597

1598+
/*
1599+
* table_needs_toast_table - does this relation need a toast table?
1600+
*/
1601+
staticinlinebool
1602+
table_relation_needs_toast_table(Relationrel)
1603+
{
1604+
returnrel->rd_tableam->relation_needs_toast_table(rel);
1605+
}
1606+
1607+
15881608
/* ----------------------------------------------------------------------------
15891609
* Planner related functionality
15901610
* ----------------------------------------------------------------------------

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