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Apply the "nodeAgg" optimization to more of the builtin transition

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functions. This patch optimizes int2_sum(), int4_sum(), float4_accum()
and float8_accum() to avoid needing to copy the transition function's
state for each input tuple of the aggregate. In an extreme case
(e.g. SELECT sum(int2_col) FROM table where table has a single column),
it improves performance by about 20%. For more complex queries or tables
with wider rows, the relative performance improvement will not be as
significant.
This commit is contained in:
Neil Conway
2005-04-06 23:56:07 +00:00
parent a6bbfedcf7
commit be2f825d51
2 changed files with 112 additions and 36 deletions
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74
src/backend/utils/adt/float.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.113 2005/02/11 04:08:58 neilc Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.114 2005/04/06 23:56:07 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@ -1902,8 +1902,6 @@ float8_accum(PG_FUNCTION_ARGS)
float8 N,
sumX,
sumX2;
Datum transdatums[3];
ArrayType *result;
transvalues = check_float8_array(transarray, "float8_accum");
N = transvalues[0];
@ -1914,15 +1912,35 @@ float8_accum(PG_FUNCTION_ARGS)
sumX += newval;
sumX2 += newval * newval;
transdatums[0] = Float8GetDatumFast(N);
transdatums[1] = Float8GetDatumFast(sumX);
transdatums[2] = Float8GetDatumFast(sumX2);
/*
* If we're invoked by nodeAgg, we can cheat and modify our first
* parameter in-place to reduce palloc overhead. Otherwise we
* construct a new array with the updated transition data and
* return it.
*/
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
transvalues[0] = N;
transvalues[1] = sumX;
transvalues[2] = sumX2;
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), false /* float8 byval */ , 'd');
PG_RETURN_ARRAYTYPE_P(transarray);
}
else
{
Datum transdatums[3];
ArrayType *result;
PG_RETURN_ARRAYTYPE_P(result);
transdatums[0] = Float8GetDatumFast(N);
transdatums[1] = Float8GetDatumFast(sumX);
transdatums[2] = Float8GetDatumFast(sumX2);
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), false /* float8 byval */ , 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
}
Datum
@ -1935,8 +1953,6 @@ float4_accum(PG_FUNCTION_ARGS)
sumX,
sumX2,
newval;
Datum transdatums[3];
ArrayType *result;
transvalues = check_float8_array(transarray, "float4_accum");
N = transvalues[0];
@ -1950,15 +1966,35 @@ float4_accum(PG_FUNCTION_ARGS)
sumX += newval;
sumX2 += newval * newval;
transdatums[0] = Float8GetDatumFast(N);
transdatums[1] = Float8GetDatumFast(sumX);
transdatums[2] = Float8GetDatumFast(sumX2);
/*
* If we're invoked by nodeAgg, we can cheat and modify our first
* parameter in-place to reduce palloc overhead. Otherwise we
* construct a new array with the updated transition data and
* return it.
*/
if (fcinfo->context && IsA(fcinfo->context, AggState))
{
transvalues[0] = N;
transvalues[1] = sumX;
transvalues[2] = sumX2;
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), false /* float8 byval */ , 'd');
PG_RETURN_ARRAYTYPE_P(transarray);
}
else
{
Datum transdatums[3];
ArrayType *result;
PG_RETURN_ARRAYTYPE_P(result);
transdatums[0] = Float8GetDatumFast(N);
transdatums[1] = Float8GetDatumFast(sumX);
transdatums[2] = Float8GetDatumFast(sumX2);
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), false /* float8 byval */ , 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
}
Datum