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-rw-r--r--contrib/spi/moddatetime.c130
-rw-r--r--contrib/spi/moddatetime.control5
2 files changed, 135 insertions, 0 deletions
diff --git a/contrib/spi/moddatetime.c b/contrib/spi/moddatetime.c
new file mode 100644
index 0000000..3eb7004
--- /dev/null
+++ b/contrib/spi/moddatetime.c
@@ -0,0 +1,130 @@
+/*
+moddatetime.c
+
+contrib/spi/moddatetime.c
+
+What is this?
+It is a function to be called from a trigger for the purpose of updating
+a modification datetime stamp in a record when that record is UPDATEd.
+
+Credits
+This is 95%+ based on autoinc.c, which I used as a starting point as I do
+not really know what I am doing. I also had help from
+Jan Wieck <jwieck@debis.com> who told me about the timestamp_in("now") function.
+OH, me, I'm Terry Mackintosh <terry@terrym.com>
+*/
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_type.h"
+#include "commands/trigger.h"
+#include "executor/spi.h"
+#include "utils/builtins.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(moddatetime);
+
+Datum
+moddatetime(PG_FUNCTION_ARGS)
+{
+ TriggerData *trigdata = (TriggerData *) fcinfo->context;
+ Trigger *trigger; /* to get trigger name */
+ int nargs; /* # of arguments */
+ int attnum; /* positional number of field to change */
+ Oid atttypid; /* type OID of field to change */
+ Datum newdt; /* The current datetime. */
+ bool newdtnull; /* null flag for it */
+ char **args; /* arguments */
+ char *relname; /* triggered relation name */
+ Relation rel; /* triggered relation */
+ HeapTuple rettuple = NULL;
+ TupleDesc tupdesc; /* tuple description */
+
+ if (!CALLED_AS_TRIGGER(fcinfo))
+ /* internal error */
+ elog(ERROR, "moddatetime: not fired by trigger manager");
+
+ if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+ /* internal error */
+ elog(ERROR, "moddatetime: must be fired for row");
+
+ if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
+ /* internal error */
+ elog(ERROR, "moddatetime: must be fired before event");
+
+ if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+ /* internal error */
+ elog(ERROR, "moddatetime: cannot process INSERT events");
+ else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
+ rettuple = trigdata->tg_newtuple;
+ else
+ /* internal error */
+ elog(ERROR, "moddatetime: cannot process DELETE events");
+
+ rel = trigdata->tg_relation;
+ relname = SPI_getrelname(rel);
+
+ trigger = trigdata->tg_trigger;
+
+ nargs = trigger->tgnargs;
+
+ if (nargs != 1)
+ /* internal error */
+ elog(ERROR, "moddatetime (%s): A single argument was expected", relname);
+
+ args = trigger->tgargs;
+ /* must be the field layout? */
+ tupdesc = rel->rd_att;
+
+ /*
+ * This gets the position in the tuple of the field we want. args[0] being
+ * the name of the field to update, as passed in from the trigger.
+ */
+ attnum = SPI_fnumber(tupdesc, args[0]);
+
+ /*
+ * This is where we check to see if the field we are supposed to update
+ * even exists.
+ */
+ if (attnum <= 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+ errmsg("\"%s\" has no attribute \"%s\"",
+ relname, args[0])));
+
+ /*
+ * Check the target field has an allowed type, and get the current
+ * datetime as a value of that type.
+ */
+ atttypid = SPI_gettypeid(tupdesc, attnum);
+ if (atttypid == TIMESTAMPOID)
+ newdt = DirectFunctionCall3(timestamp_in,
+ CStringGetDatum("now"),
+ ObjectIdGetDatum(InvalidOid),
+ Int32GetDatum(-1));
+ else if (atttypid == TIMESTAMPTZOID)
+ newdt = DirectFunctionCall3(timestamptz_in,
+ CStringGetDatum("now"),
+ ObjectIdGetDatum(InvalidOid),
+ Int32GetDatum(-1));
+ else
+ {
+ ereport(ERROR,
+ (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+ errmsg("attribute \"%s\" of \"%s\" must be type TIMESTAMP or TIMESTAMPTZ",
+ args[0], relname)));
+ newdt = (Datum) 0; /* keep compiler quiet */
+ }
+ newdtnull = false;
+
+ /* Replace the attnum'th column with newdt */
+ rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
+ 1, &attnum, &newdt, &newdtnull);
+
+ /* Clean up */
+ pfree(relname);
+
+ return PointerGetDatum(rettuple);
+}
diff --git a/contrib/spi/moddatetime.control b/contrib/spi/moddatetime.control
new file mode 100644
index 0000000..93dfac5
--- /dev/null
+++ b/contrib/spi/moddatetime.control
@@ -0,0 +1,5 @@
+# moddatetime extension
+comment = 'functions for tracking last modification time'
+default_version = '1.0'
+module_pathname = '$libdir/moddatetime'
+relocatable = true