mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-12-21 08:29:39 +08:00
5b0c9d3603
a physically separate type. Defining 'lo' as a domain over OID works just fine and is more efficient. Improve documentation and fix up the test script. (Would like to turn test script into a proper regression test, but right now its output is not constant because of numeric OIDs; plus it makes Unix-specific assumptions about files it can import.)
112 lines
2.5 KiB
C
112 lines
2.5 KiB
C
/*
|
|
* PostgreSQL definitions for managed Large Objects.
|
|
*
|
|
* $PostgreSQL: pgsql/contrib/lo/lo.c,v 1.15 2005/06/23 00:06:37 tgl Exp $
|
|
*
|
|
*/
|
|
|
|
#include "postgres.h"
|
|
|
|
/* Required for largeobjects */
|
|
#include "libpq/libpq-fs.h"
|
|
#include "libpq/be-fsstubs.h"
|
|
|
|
/* Required for SPI */
|
|
#include "executor/spi.h"
|
|
|
|
/* Required for triggers */
|
|
#include "commands/trigger.h"
|
|
|
|
|
|
#define atooid(x) ((Oid) strtoul((x), NULL, 10))
|
|
|
|
|
|
/* forward declarations */
|
|
Datum lo_manage(PG_FUNCTION_ARGS);
|
|
|
|
|
|
/*
|
|
* This is the trigger that protects us from orphaned large objects
|
|
*/
|
|
PG_FUNCTION_INFO_V1(lo_manage);
|
|
|
|
Datum
|
|
lo_manage(PG_FUNCTION_ARGS)
|
|
{
|
|
TriggerData *trigdata = (TriggerData *) fcinfo->context;
|
|
int attnum; /* attribute number to monitor */
|
|
char **args; /* Args containing attr name */
|
|
TupleDesc tupdesc; /* Tuple Descriptor */
|
|
HeapTuple rettuple; /* Tuple to be returned */
|
|
bool isdelete; /* are we deleting? */
|
|
HeapTuple newtuple; /* The new value for tuple */
|
|
HeapTuple trigtuple; /* The original value of tuple */
|
|
|
|
if (!CALLED_AS_TRIGGER(fcinfo)) /* internal error */
|
|
elog(ERROR, "not fired by trigger manager");
|
|
|
|
/*
|
|
* Fetch some values from trigdata
|
|
*/
|
|
newtuple = trigdata->tg_newtuple;
|
|
trigtuple = trigdata->tg_trigtuple;
|
|
tupdesc = trigdata->tg_relation->rd_att;
|
|
args = trigdata->tg_trigger->tgargs;
|
|
|
|
/* tuple to return to Executor */
|
|
if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
|
|
rettuple = newtuple;
|
|
else
|
|
rettuple = trigtuple;
|
|
|
|
/* Are we deleting the row? */
|
|
isdelete = TRIGGER_FIRED_BY_DELETE(trigdata->tg_event);
|
|
|
|
/* Get the column we're interested in */
|
|
attnum = SPI_fnumber(tupdesc, args[0]);
|
|
|
|
if (attnum <= 0)
|
|
elog(ERROR, "column \"%s\" does not exist", args[0]);
|
|
|
|
/*
|
|
* Handle updates
|
|
*
|
|
* Here, if the value of the monitored attribute changes, then the large
|
|
* object associated with the original value is unlinked.
|
|
*/
|
|
if (newtuple != NULL)
|
|
{
|
|
char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
|
|
char *newv = SPI_getvalue(newtuple, tupdesc, attnum);
|
|
|
|
if (orig != NULL && (newv == NULL || strcmp(orig, newv) != 0))
|
|
DirectFunctionCall1(lo_unlink,
|
|
ObjectIdGetDatum(atooid(orig)));
|
|
|
|
if (newv)
|
|
pfree(newv);
|
|
if (orig)
|
|
pfree(orig);
|
|
}
|
|
|
|
/*
|
|
* Handle deleting of rows
|
|
*
|
|
* Here, we unlink the large object associated with the managed attribute
|
|
*/
|
|
if (isdelete)
|
|
{
|
|
char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
|
|
|
|
if (orig != NULL)
|
|
{
|
|
DirectFunctionCall1(lo_unlink,
|
|
ObjectIdGetDatum(atooid(orig)));
|
|
|
|
pfree(orig);
|
|
}
|
|
}
|
|
|
|
return PointerGetDatum(rettuple);
|
|
}
|