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Tweak accumArrayResult() to double the size of its working arrays when

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more space is needed, instead of incrementing by a fixed amount; the old
method wastes lots of space and time when the ultimate size is large.
Per gripe from Tatsuo.
This commit is contained in:
Tom Lane
2006-11-08 19:24:38 +00:00
parent a5cf12e2ef
commit fc5eb3f69a
2 changed files with 11 additions and 18 deletions
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18
src/backend/utils/adt/arrayfuncs.c
View File

@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.134 2006/10/06 17:13:59 petere Exp $ * $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.135 2006/11/08 19:24:38 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -4337,10 +4337,9 @@ accumArrayResult(ArrayBuildState *astate,
oldcontext = MemoryContextSwitchTo(arr_context); oldcontext = MemoryContextSwitchTo(arr_context);
astate = (ArrayBuildState *) palloc(sizeof(ArrayBuildState)); astate = (ArrayBuildState *) palloc(sizeof(ArrayBuildState));
astate->mcontext = arr_context; astate->mcontext = arr_context;
astate->dvalues = (Datum *) astate->alen = 64; /* arbitrary starting array size */
palloc(ARRAY_ELEMS_CHUNKSIZE * sizeof(Datum)); astate->dvalues = (Datum *) palloc(astate->alen * sizeof(Datum));
astate->dnulls = (bool *) astate->dnulls = (bool *) palloc(astate->alen * sizeof(bool));
palloc(ARRAY_ELEMS_CHUNKSIZE * sizeof(bool));
astate->nelems = 0; astate->nelems = 0;
astate->element_type = element_type; astate->element_type = element_type;
get_typlenbyvalalign(element_type, get_typlenbyvalalign(element_type,
@ -4353,14 +4352,13 @@ accumArrayResult(ArrayBuildState *astate,
oldcontext = MemoryContextSwitchTo(astate->mcontext); oldcontext = MemoryContextSwitchTo(astate->mcontext);
Assert(astate->element_type == element_type); Assert(astate->element_type == element_type);
/* enlarge dvalues[]/dnulls[] if needed */ /* enlarge dvalues[]/dnulls[] if needed */
if ((astate->nelems % ARRAY_ELEMS_CHUNKSIZE) == 0) if (astate->nelems >= astate->alen)
{ {
astate->alen *= 2;
astate->dvalues = (Datum *) astate->dvalues = (Datum *)
repalloc(astate->dvalues, repalloc(astate->dvalues, astate->alen * sizeof(Datum));
(astate->nelems + ARRAY_ELEMS_CHUNKSIZE) * sizeof(Datum));
astate->dnulls = (bool *) astate->dnulls = (bool *)
repalloc(astate->dnulls, repalloc(astate->dnulls, astate->alen * sizeof(bool));
(astate->nelems + ARRAY_ELEMS_CHUNKSIZE) * sizeof(bool));
} }
} }

11
src/include/utils/array.h
View File

@ -49,7 +49,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $PostgreSQL: pgsql/src/include/utils/array.h,v 1.59 2006/09/10 20:14:20 tgl Exp $ * $PostgreSQL: pgsql/src/include/utils/array.h,v 1.60 2006/11/08 19:24:38 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -78,13 +78,8 @@ typedef struct ArrayBuildState
MemoryContext mcontext; /* where all the temp stuff is kept */ MemoryContext mcontext; /* where all the temp stuff is kept */
Datum *dvalues; /* array of accumulated Datums */ Datum *dvalues; /* array of accumulated Datums */
bool *dnulls; /* array of is-null flags for Datums */ bool *dnulls; /* array of is-null flags for Datums */
int alen; /* allocated length of above arrays */
/* int nelems; /* number of valid entries in above arrays */
* The allocated size of dvalues[] and dnulls[] is always a multiple of
* ARRAY_ELEMS_CHUNKSIZE
*/
#define ARRAY_ELEMS_CHUNKSIZE 64
int nelems; /* number of valid Datums in dvalues[] */
Oid element_type; /* data type of the Datums */ Oid element_type; /* data type of the Datums */
int16 typlen; /* needed info about datatype */ int16 typlen; /* needed info about datatype */
bool typbyval; bool typbyval;