caaf2e8469
Various places were testing TRIGGER_FIRED_BEFORE() where what they really meant was !TRIGGER_FIRED_AFTER(), or vice versa. This needs to be cleaned up because there are about to be more than two possible states. We might want to note this in the 9.1 release notes as something for trigger authors to double-check. For consistency's sake I also changed some places that assumed that TRIGGER_FIRED_FOR_ROW and TRIGGER_FIRED_FOR_STATEMENT are necessarily mutually exclusive; that's not in immediate danger of breaking, but it's still sloppier than it should be. Extracted from Dean Rasheed's patch for triggers on views. I'm committing this separately since it's an identifiable separate issue, and is the only reason for the patch to touch most of these particular files.
130 lines
3.7 KiB
C
130 lines
3.7 KiB
C
/*
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moddatetime.c
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contrib/spi/moddatetime.c
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What is this?
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It is a function to be called from a trigger for the purpose of updating
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a modification datetime stamp in a record when that record is UPDATEd.
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Credits
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This is 95%+ based on autoinc.c, which I used as a starting point as I do
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not really know what I am doing. I also had help from
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Jan Wieck <jwieck@debis.com> who told me about the timestamp_in("now") function.
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OH, me, I'm Terry Mackintosh <terry@terrym.com>
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*/
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#include "postgres.h"
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#include "catalog/pg_type.h"
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#include "executor/spi.h"
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#include "commands/trigger.h"
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PG_MODULE_MAGIC;
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extern Datum moddatetime(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(moddatetime);
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Datum
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moddatetime(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 attnum; /* positional number of field to change */
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Datum newdt; /* The current datetime. */
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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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if (!CALLED_AS_TRIGGER(fcinfo))
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/* internal error */
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elog(ERROR, "moddatetime: not fired by trigger manager");
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if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "moddatetime: must be fired for row");
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if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "moddatetime: must be fired before event");
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if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "moddatetime: cannot process INSERT events");
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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, "moddatetime: cannot 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 != 1)
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/* internal error */
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elog(ERROR, "moddatetime (%s): A single argument was expected", relname);
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args = trigger->tgargs;
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/* must be the field layout? */
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tupdesc = rel->rd_att;
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/* Get the current datetime. */
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newdt = DirectFunctionCall3(timestamp_in,
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CStringGetDatum("now"),
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ObjectIdGetDatum(InvalidOid),
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Int32GetDatum(-1));
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/*
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* This gets the position in the tuple of the field we want. args[0] being
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* the name of the field to update, as passed in from the trigger.
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*/
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attnum = SPI_fnumber(tupdesc, args[0]);
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/*
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* This is were we check to see if the field we are supposed to update
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* even exits. The above function must return -1 if name not found?
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*/
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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[0])));
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/*
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* OK, this is where we make sure the timestamp field that we are
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* modifying is really a timestamp field. Hay, error checking, what a
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* novel idea !-)
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*/
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if (SPI_gettypeid(tupdesc, attnum) != TIMESTAMPOID)
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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 TIMESTAMP",
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args[0], relname)));
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/* 1 is the number of items in the arrays attnum and newdt.
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attnum is the positional number of the field to be updated.
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newdt is the new datetime stamp.
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NOTE that attnum and newdt are not arrays, but then a 1 ellement array
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is not an array any more then they are. Thus, they can be considered a
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one element array.
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*/
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rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newdt, NULL);
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if (rettuple == NULL)
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/* internal error */
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elog(ERROR, "moddatetime (%s): %d returned by SPI_modifytuple",
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relname, SPI_result);
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/* Clean up */
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pfree(relname);
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return PointerGetDatum(rettuple);
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}
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