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Commit0229106

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Overload index_form_tuple to allow the memory context to be supplied
40af10b changed things so we make use of a generation memory context forstoring tuples to be sorted by tuplesort.c. That change does not playnicely with the changes made in9f03ca9 (back in 2014). That commitchanged things so that index_form_tuple() is called while switched intothe tuplestore's tuplecontext. In order to fetch the tuple from the index,index_form_tuple() must do various memory allocations which are unrelatedto the storage of the final returned tuple. Although all of theseallocations are pfree'd, the fact that we now use a generation contextmeans that the memory for these pfree'd allocations won't be used again byany other allocation due to generation.c's lack of freelists. This couldresult in sorts used for building indexes exceeding maintenance_work_memby a very large amount.Here we fix it so we no longer allocate anything apart from the tupleitself into the generation context by adding a new version ofindex_form_tuple named index_form_tuple_context, which can be called tospecify the MemoryContext to allocate the tuple into.Discussion:https://postgr.es/m/CAApHDvrHQkiFRHiGiAS-LMOvJN-eK-s762=tVzBz8ZqUea-a_A@mail.gmail.comBackpatch-through: 15, where40af10b was added.
1 parent2d7ead8 commit0229106

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3 files changed

+31
-8
lines changed

3 files changed

+31
-8
lines changed

‎src/backend/access/common/indextuple.c

Lines changed: 24 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -33,20 +33,39 @@
3333
* ----------------------------------------------------------------
3434
*/
3535

36+
/* ----------------
37+
*index_form_tuple
38+
*
39+
*As index_form_tuple_context, but allocates the returned tuple in the
40+
*CurrentMemoryContext.
41+
* ----------------
42+
*/
43+
IndexTuple
44+
index_form_tuple(TupleDesctupleDescriptor,
45+
Datum*values,
46+
bool*isnull)
47+
{
48+
returnindex_form_tuple_context(tupleDescriptor,values,isnull,
49+
CurrentMemoryContext);
50+
}
51+
3652
/* ----------------
37-
*index_form_tuple
53+
*index_form_tuple_context
3854
*
3955
*This shouldn't leak any memory; otherwise, callers such as
4056
*tuplesort_putindextuplevalues() will be very unhappy.
4157
*
4258
*This shouldn't perform external table access provided caller
4359
*does not pass values that are stored EXTERNAL.
60+
*
61+
*Allocates returned tuple in provided 'context'.
4462
* ----------------
4563
*/
4664
IndexTuple
47-
index_form_tuple(TupleDesctupleDescriptor,
48-
Datum*values,
49-
bool*isnull)
65+
index_form_tuple_context(TupleDesctupleDescriptor,
66+
Datum*values,
67+
bool*isnull,
68+
MemoryContextcontext)
5069
{
5170
char*tp;/* tuple pointer */
5271
IndexTupletuple;/* return tuple */
@@ -143,7 +162,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
143162
size=hoff+data_size;
144163
size=MAXALIGN(size);/* be conservative */
145164

146-
tp= (char*)palloc0(size);
165+
tp= (char*)MemoryContextAllocZero(context,size);
147166
tuple= (IndexTuple)tp;
148167

149168
heap_fill_tuple(tupleDescriptor,

‎src/backend/utils/sort/tuplesort.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1884,12 +1884,13 @@ tuplesort_putindextuplevalues(Tuplesortstate *state, Relation rel,
18841884
ItemPointerself,Datum*values,
18851885
bool*isnull)
18861886
{
1887-
MemoryContextoldcontext=MemoryContextSwitchTo(state->tuplecontext);
1887+
MemoryContextoldcontext;
18881888
SortTuplestup;
18891889
Datumoriginal;
18901890
IndexTupletuple;
18911891

1892-
stup.tuple=index_form_tuple(RelationGetDescr(rel),values,isnull);
1892+
stup.tuple=index_form_tuple_context(RelationGetDescr(rel),values,
1893+
isnull,state->tuplecontext);
18931894
tuple= ((IndexTuple)stup.tuple);
18941895
tuple->t_tid=*self;
18951896
USEMEM(state,GetMemoryChunkSpace(stup.tuple));
@@ -1899,7 +1900,7 @@ tuplesort_putindextuplevalues(Tuplesortstate *state, Relation rel,
18991900
RelationGetDescr(state->indexRel),
19001901
&stup.isnull1);
19011902

1902-
MemoryContextSwitchTo(state->sortcontext);
1903+
oldcontext=MemoryContextSwitchTo(state->sortcontext);
19031904

19041905
if (!state->sortKeys|| !state->sortKeys->abbrev_converter||stup.isnull1)
19051906
{

‎src/include/access/itup.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -150,6 +150,9 @@ typedef IndexAttributeBitMapData * IndexAttributeBitMap;
150150
/* routines in indextuple.c */
151151
externIndexTupleindex_form_tuple(TupleDesctupleDescriptor,
152152
Datum*values,bool*isnull);
153+
externIndexTupleindex_form_tuple_context(TupleDesctupleDescriptor,
154+
Datum*values,bool*isnull,
155+
MemoryContextcontext);
153156
externDatumnocache_index_getattr(IndexTupletup,intattnum,
154157
TupleDesctupleDesc);
155158
externvoidindex_deform_tuple(IndexTupletup,TupleDesctupleDescriptor,

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