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/*
* contrib/spi/autoinc.c
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/pg_type.h"
#include "commands/sequence.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/rel.h"
PG_MODULE_MAGIC_EXT(
.name = "autoinc",
.version = PG_VERSION
);
PG_FUNCTION_INFO_V1(autoinc);
Datum
autoinc(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
Trigger *trigger; /* to get trigger name */
int nargs; /* # of arguments */
int *chattrs; /* attnums of attributes to change */
int chnattrs = 0; /* # of above */
Datum *newvals; /* vals of above */
bool *newnulls; /* null flags for above */
char **args; /* arguments */
char *relname; /* triggered relation name */
Relation rel; /* triggered relation */
HeapTuple rettuple = NULL;
TupleDesc tupdesc; /* tuple description */
bool isnull;
int i;
if (!CALLED_AS_TRIGGER(fcinfo))
/* internal error */
elog(ERROR, "not fired by trigger manager");
if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
/* internal error */
elog(ERROR, "must be fired for row");
if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
/* internal error */
elog(ERROR, "must be fired before event");
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
rettuple = trigdata->tg_trigtuple;
else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
rettuple = trigdata->tg_newtuple;
else
/* internal error */
elog(ERROR, "cannot process DELETE events");
rel = trigdata->tg_relation;
relname = SPI_getrelname(rel);
trigger = trigdata->tg_trigger;
nargs = trigger->tgnargs;
if (nargs <= 0 || nargs % 2 != 0)
/* internal error */
elog(ERROR, "autoinc (%s): even number gt 0 of arguments was expected", relname);
args = trigger->tgargs;
tupdesc = rel->rd_att;
chattrs = (int *) palloc(nargs / 2 * sizeof(int));
newvals = (Datum *) palloc(nargs / 2 * sizeof(Datum));
newnulls = (bool *) palloc(nargs / 2 * sizeof(bool));
for (i = 0; i < nargs;)
{
int attnum = SPI_fnumber(tupdesc, args[i]);
int32 val;
Datum seqname;
if (attnum <= 0)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("\"%s\" has no attribute \"%s\"",
relname, args[i])));
if (SPI_gettypeid(tupdesc, attnum) != INT4OID)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("attribute \"%s\" of \"%s\" must be type INT4",
args[i], relname)));
val = DatumGetInt32(SPI_getbinval(rettuple, tupdesc, attnum, &isnull));
if (!isnull && val != 0)
{
i += 2;
continue;
}
i++;
chattrs[chnattrs] = attnum;
seqname = CStringGetTextDatum(args[i]);
newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
/* nextval now returns int64; coerce down to int32 */
newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
if (DatumGetInt32(newvals[chnattrs]) == 0)
{
newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
}
newnulls[chnattrs] = false;
pfree(DatumGetTextPP(seqname));
chnattrs++;
i++;
}
if (chnattrs > 0)
{
rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
chnattrs, chattrs,
newvals, newnulls);
}
pfree(relname);
pfree(chattrs);
pfree(newvals);
pfree(newnulls);
return PointerGetDatum(rettuple);
}
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