database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-22 14:32:25 +03:00
Code Activity

Revise aggregate functions per earlier discussions in pghackers.

Browse Source 
There's now only one transition value and transition function.
NULL handling in aggregates is a lot cleaner.  Also, use Numeric
accumulators instead of integer accumulators for sum/avg on integer
datatypes --- this avoids overflow at the cost of being a little slower.
Implement VARIANCE() and STDDEV() aggregates in the standard backend.

Also, enable new LIKE selectivity estimators by default.  Unrelated
change, but as long as I had to force initdb anyway...
This commit is contained in:
Tom Lane
2000-07-17 03:05:41 +00:00
parent 139f19c302
commit bec98a31c5
55 changed files with 1949 additions and 1813 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
src/backend/utils/adt/timestamp.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.33 2000/07/12 22:59:09 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.34 2000/07/17 03:05:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -29,6 +29,7 @@
#include "access/hash.h"
#include "access/xact.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/builtins.h"
@@ -882,10 +883,6 @@ overlaps_timestamp(PG_FUNCTION_ARGS)
/*----------------------------------------------------------
* "Arithmetic" operators on date/times.
* timestamp_foo returns foo as an object (pointer) that
* can be passed between languages.
* timestamp_xx is an internal routine which returns the
* actual value.
*---------------------------------------------------------*/
Datum
@@ -1150,7 +1147,6 @@ interval_larger(PG_FUNCTION_ARGS)
PG_RETURN_INTERVAL_P(result);
}
Datum
interval_pl(PG_FUNCTION_ARGS)
{
@@ -1232,6 +1228,90 @@ interval_div(PG_FUNCTION_ARGS)
PG_RETURN_INTERVAL_P(result);
}
/*
* interval_accum and interval_avg implement the AVG(interval) aggregate.
*
* The transition datatype for this aggregate is a 2-element array of
* intervals, where the first is the running sum and the second contains
* the number of values so far in its 'time' field. This is a bit ugly
* but it beats inventing a specialized datatype for the purpose.
*/
Datum
interval_accum(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
Interval *newval = PG_GETARG_INTERVAL_P(1);
Datum *transdatums;
int ndatums;
Interval sumX,
N;
Interval *newsum;
ArrayType *result;
/* We assume the input is array of interval */
deconstruct_array(transarray,
false, 12, 'd',
&transdatums, &ndatums);
if (ndatums != 2)
elog(ERROR, "interval_accum: expected 2-element interval array");
/*
* XXX memcpy, instead of just extracting a pointer, to work around
* buggy array code: it won't ensure proper alignment of Interval
* objects on machines where double requires 8-byte alignment.
* That should be fixed, but in the meantime...
*/
memcpy(&sumX, DatumGetIntervalP(transdatums[0]), sizeof(Interval));
memcpy(&N, DatumGetIntervalP(transdatums[1]), sizeof(Interval));
newsum = DatumGetIntervalP(DirectFunctionCall2(interval_pl,
IntervalPGetDatum(&sumX),
IntervalPGetDatum(newval)));
N.time += 1;
transdatums[0] = IntervalPGetDatum(newsum);
transdatums[1] = IntervalPGetDatum(&N);
result = construct_array(transdatums, 2,
false, 12, 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
Datum
interval_avg(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
Datum *transdatums;
int ndatums;
Interval sumX,
N;
/* We assume the input is array of interval */
deconstruct_array(transarray,
false, 12, 'd',
&transdatums, &ndatums);
if (ndatums != 2)
elog(ERROR, "interval_avg: expected 2-element interval array");
/*
* XXX memcpy, instead of just extracting a pointer, to work around
* buggy array code: it won't ensure proper alignment of Interval
* objects on machines where double requires 8-byte alignment.
* That should be fixed, but in the meantime...
*/
memcpy(&sumX, DatumGetIntervalP(transdatums[0]), sizeof(Interval));
memcpy(&N, DatumGetIntervalP(transdatums[1]), sizeof(Interval));
/* SQL92 defines AVG of no values to be NULL */
if (N.time == 0)
PG_RETURN_NULL();
return DirectFunctionCall2(interval_div,
IntervalPGetDatum(&sumX),
Float8GetDatum(N.time));
}
/* timestamp_age()
* Calculate time difference while retaining year/month fields.
* Note that this does not result in an accurate absolute time span