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