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#include "executor/spi.h" /* this is what you need to work with SPI */
#include "commands/trigger.h" /* -"- and triggers */
HeapTuple autoinc(void);
extern int4 nextval(struct varlena * seqin);
HeapTuple
autoinc()
{
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 */
char **args; /* arguments */
char *relname; /* triggered relation name */
Relation rel; /* triggered relation */
HeapTuple rettuple = NULL;
TupleDesc tupdesc; /* tuple description */
bool isnull;
int i;
if (!CurrentTriggerData)
elog(ERROR, "autoinc: triggers are not initialized");
if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))
elog(ERROR, "autoinc: can't process STATEMENT events");
if (TRIGGER_FIRED_AFTER(CurrentTriggerData->tg_event))
elog(ERROR, "autoinc: must be fired before event");
if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
rettuple = CurrentTriggerData->tg_trigtuple;
else if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
rettuple = CurrentTriggerData->tg_newtuple;
else
elog(ERROR, "autoinc: can't process DELETE events");
rel = CurrentTriggerData->tg_relation;
relname = SPI_getrelname(rel);
trigger = CurrentTriggerData->tg_trigger;
nargs = trigger->tgnargs;
if (nargs <= 0 || nargs % 2 != 0)
elog(ERROR, "autoinc (%s): even number gt 0 of arguments was expected", relname);
args = trigger->tgargs;
tupdesc = rel->rd_att;
CurrentTriggerData = NULL;
chattrs = (int *) palloc (nargs/2 * sizeof (int));
newvals = (Datum *) palloc (nargs/2 * sizeof (Datum));
for (i = 0; i < nargs; )
{
struct varlena *seqname;
int attnum = SPI_fnumber (tupdesc, args[i]);
int32 val;
if ( attnum < 0 )
elog(ERROR, "autoinc (%s): there is no attribute %s", relname, args[i]);
if (SPI_gettypeid (tupdesc, attnum) != INT4OID)
elog(ERROR, "autoinc (%s): attribute %s must be of INT4 type",
relname, args[i]);
val = DatumGetInt32 (SPI_getbinval (rettuple, tupdesc, attnum, &isnull));
if (!isnull && val != 0)
{
i += 2;
continue;
}
i++;
chattrs[chnattrs] = attnum;
seqname = textin (args[i]);
newvals[chnattrs] = Int32GetDatum (nextval (seqname));
if ( DatumGetInt32 (newvals[chnattrs]) == 0 )
newvals[chnattrs] = Int32GetDatum (nextval (seqname));
pfree (seqname);
chnattrs++;
i++;
}
if (chnattrs > 0)
{
rettuple = SPI_modifytuple (rel, rettuple, chnattrs, chattrs, newvals, NULL);
if ( rettuple == NULL )
elog (ERROR, "autoinc (%s): %d returned by SPI_modifytuple",
relname, SPI_result);
}
pfree (relname);
pfree (chattrs);
pfree (newvals);
return (rettuple);
}
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