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In array_agg(), don't create a new context for every group.

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Previously, each new array created a new memory context that started
out at 8kB. This is incredibly wasteful when there are lots of small
groups of just a few elements each.

Change initArrayResult() and friends to accept a "subcontext" argument
to indicate whether the caller wants the ArrayBuildState allocated in
a new subcontext or not. If not, it can no longer be released
separately from the rest of the memory context.

Fixes bug report by Frank van Vugt on 2013-10-19.

Tomas Vondra. Reviewed by Ali Akbar, Tom Lane, and me.
This commit is contained in:
Jeff Davis
2015-02-21 17:24:48 -08:00
parent e9fd5545de
commit b419865a81
6 changed files with 92 additions and 44 deletions
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8
src/include/utils/array.h
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@@ -89,6 +89,7 @@ typedef struct ArrayBuildState
int16 typlen; /* needed info about datatype */
bool typbyval;
char typalign;
bool private_cxt; /* use private memory context */
} ArrayBuildState;
/*
@@ -109,6 +110,7 @@ typedef struct ArrayBuildStateArr
int lbs[MAXDIM];
Oid array_type; /* data type of the arrays */
Oid element_type; /* data type of the array elements */
bool private_cxt; /* use private memory context */
} ArrayBuildStateArr;
/*
@@ -293,7 +295,7 @@ extern void deconstruct_array(ArrayType *array,
extern bool array_contains_nulls(ArrayType *array);
extern ArrayBuildState *initArrayResult(Oid element_type,
MemoryContext rcontext);
MemoryContext rcontext, bool subcontext);
extern ArrayBuildState *accumArrayResult(ArrayBuildState *astate,
Datum dvalue, bool disnull,
Oid element_type,
@@ -304,7 +306,7 @@ extern Datum makeMdArrayResult(ArrayBuildState *astate, int ndims,
int *dims, int *lbs, MemoryContext rcontext, bool release);
extern ArrayBuildStateArr *initArrayResultArr(Oid array_type, Oid element_type,
MemoryContext rcontext);
MemoryContext rcontext, bool subcontext);
extern ArrayBuildStateArr *accumArrayResultArr(ArrayBuildStateArr *astate,
Datum dvalue, bool disnull,
Oid array_type,
@@ -313,7 +315,7 @@ extern Datum makeArrayResultArr(ArrayBuildStateArr *astate,
MemoryContext rcontext, bool release);
extern ArrayBuildStateAny *initArrayResultAny(Oid input_type,
MemoryContext rcontext);
MemoryContext rcontext, bool subcontext);
extern ArrayBuildStateAny *accumArrayResultAny(ArrayBuildStateAny *astate,
Datum dvalue, bool disnull,
Oid input_type,