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-rw-r--r--contrib/spi/autoinc.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/contrib/spi/autoinc.c b/contrib/spi/autoinc.c
new file mode 100644
index 0000000..8bf7422
--- /dev/null
+++ b/contrib/spi/autoinc.c
@@ -0,0 +1,127 @@
+/*
+ * 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;
+
+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);
+}