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121 lines
3.3 KiB
C
121 lines
3.3 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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#include "commands/sequence.h" /* for nextval() */
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PG_MODULE_MAGIC;
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extern Datum autoinc(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(autoinc);
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Datum
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autoinc(PG_FUNCTION_ARGS)
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{
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TriggerData *trigdata = (TriggerData *) fcinfo->context;
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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 (!CALLED_AS_TRIGGER(fcinfo))
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/* internal error */
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elog(ERROR, "not fired by trigger manager");
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if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "can't process STATEMENT events");
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if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "must be fired before event");
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if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
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rettuple = trigdata->tg_trigtuple;
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else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
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rettuple = trigdata->tg_newtuple;
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else
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/* internal error */
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elog(ERROR, "can't process DELETE events");
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rel = trigdata->tg_relation;
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relname = SPI_getrelname(rel);
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trigger = trigdata->tg_trigger;
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nargs = trigger->tgnargs;
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if (nargs <= 0 || nargs % 2 != 0)
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/* internal error */
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elog(ERROR, "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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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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int attnum = SPI_fnumber(tupdesc, args[i]);
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int32 val;
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Datum seqname;
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if (attnum < 0)
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ereport(ERROR,
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(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
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errmsg("\"%s\" has no attribute \"%s\"",
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relname, args[i])));
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if (SPI_gettypeid(tupdesc, attnum) != INT4OID)
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ereport(ERROR,
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(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
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errmsg("attribute \"%s\" of \"%s\" must be type INT4",
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args[i], relname)));
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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 = DirectFunctionCall1(textin,
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CStringGetDatum(args[i]));
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newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
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/* nextval now returns int64; coerce down to int32 */
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newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
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if (DatumGetInt32(newvals[chnattrs]) == 0)
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{
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newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
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newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
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}
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pfree(DatumGetTextP(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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/* internal error */
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elog(ERROR, "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 PointerGetDatum(rettuple);
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}
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