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Add function (actually an int4 and an int8 version) that generates

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a series of numbers, optionally using an explicit step size other
than the default value (one). Use function in the information_schema
to replace hard-wired knowledge of INDEX_MAX_KEYS. initdb forced due
to pg_proc change. Documentation update still needed -- will be
committed separately.
This commit is contained in:
Joe Conway
2004-02-03 08:29:57 +00:00
parent 9dac52649d
commit 12661642c8
7 changed files with 205 additions and 19 deletions
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91
src/backend/utils/adt/int.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.59 2003/12/01 21:52:37 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.60 2004/02/03 08:29:56 joe Exp $
*
*-------------------------------------------------------------------------
*/
@ -34,6 +34,7 @@
#include <ctype.h>
#include <limits.h>
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "utils/builtins.h"
@ -44,6 +45,13 @@
#define SHRT_MIN (-0x8000)
#endif
typedef struct
{
int32 current;
int32 finish;
int32 step;
} generate_series_fctx;
/*****************************************************************************
* USER I/O ROUTINES *
*****************************************************************************/
@ -1021,3 +1029,84 @@ int2shr(PG_FUNCTION_ARGS)
PG_RETURN_INT16(arg1 >> arg2);
}
/*
* non-persistent numeric series generator
*/
Datum
generate_series_int4(PG_FUNCTION_ARGS)
{
return generate_series_step_int4(fcinfo);
}
Datum
generate_series_step_int4(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
generate_series_fctx *fctx;
int32 result;
MemoryContext oldcontext;
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
int32 start = PG_GETARG_INT32(0);
int32 finish = PG_GETARG_INT32(1);
int32 step = 1;
/* see if we were given an explicit step size */
if (PG_NARGS() == 3)
step = PG_GETARG_INT32(2);
if (step == 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("step size may not equal zero")));
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/*
* switch to memory context appropriate for multiple function
* calls
*/
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* allocate memory for user context */
fctx = (generate_series_fctx *) palloc(sizeof(generate_series_fctx));
/*
* Use fctx to keep state from call to call.
* Seed current with the original start value
*/
fctx->current = start;
fctx->finish = finish;
fctx->step = step;
funcctx->user_fctx = fctx;
MemoryContextSwitchTo(oldcontext);
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
/*
* get the saved state and use current as the result for
* this iteration
*/
fctx = funcctx->user_fctx;
result = fctx->current;
if ((fctx->step > 0 && fctx->current <= fctx->finish) ||
(fctx->step < 0 && fctx->current >= fctx->finish))
{
/* increment current in preparation for next iteration */
fctx->current += fctx->step;
/* do when there is more left to send */
SRF_RETURN_NEXT(funcctx, Int32GetDatum(result));
}
else
/* do when there is no more left */
SRF_RETURN_DONE(funcctx);
}