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Adjust lo_open() so that specifying INV_READ without INV_WRITE creates

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a descriptor that uses the current transaction snapshot, rather than
SnapshotNow as it did before (and still does if INV_WRITE is set).
This means pg_dump will now dump a consistent snapshot of large object
contents, as it never could do before.  Also, add a lo_create() function
that is similar to lo_creat() but allows the desired OID of the large
object to be specified.  This will simplify pg_restore considerably
(but I'll fix that in a separate commit).
This commit is contained in:
Tom Lane
2005-06-13 02:26:53 +00:00
parent f52a34229b
commit a2fb7b8a1f
11 changed files with 265 additions and 96 deletions
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60
src/interfaces/libpq/fe-lobj.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-lobj.c,v 1.52 2004/12/31 22:03:50 pgsql Exp $
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-lobj.c,v 1.53 2005/06/13 02:26:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -266,12 +266,11 @@ lo_lseek(PGconn *conn, int fd, int offset, int whence)
/*
* lo_creat
* create a new large object
* the mode is a bitmask describing different attributes of the new object
* the mode is ignored (once upon a time it had a use)
*
* returns the oid of the large object created or
* InvalidOid upon failure
*/
Oid
lo_creat(PGconn *conn, int mode)
{
@ -303,6 +302,53 @@ lo_creat(PGconn *conn, int mode)
}
}
/*
* lo_create
* create a new large object
* if lobjId isn't InvalidOid, it specifies the OID to (attempt to) create
*
* returns the oid of the large object created or
* InvalidOid upon failure
*/
Oid
lo_create(PGconn *conn, Oid lobjId)
{
PQArgBlock argv[1];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return InvalidOid;
}
/* Must check this on-the-fly because it's not there pre-8.1 */
if (conn->lobjfuncs->fn_lo_create == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_create\n"));
return InvalidOid;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = lobjId;
res = PQfn(conn, conn->lobjfuncs->fn_lo_create,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return (Oid) retval;
}
else
{
PQclear(res);
return InvalidOid;
}
}
/*
* lo_tell
@ -560,7 +606,8 @@ lo_initialize(PGconn *conn)
/*
* Execute the query to get all the functions at once. In 7.3 and
* later we need to be schema-safe.
* later we need to be schema-safe. lo_create only exists in 8.1
* and up.
*/
if (conn->sversion >= 70300)
query = "select proname, oid from pg_catalog.pg_proc "
@ -568,6 +615,7 @@ lo_initialize(PGconn *conn)
"'lo_open', "
"'lo_close', "
"'lo_creat', "
"'lo_create', "
"'lo_unlink', "
"'lo_lseek', "
"'lo_tell', "
@ -615,6 +663,8 @@ lo_initialize(PGconn *conn)
lobjfuncs->fn_lo_close = foid;
else if (!strcmp(fname, "lo_creat"))
lobjfuncs->fn_lo_creat = foid;
else if (!strcmp(fname, "lo_create"))
lobjfuncs->fn_lo_create = foid;
else if (!strcmp(fname, "lo_unlink"))
lobjfuncs->fn_lo_unlink = foid;
else if (!strcmp(fname, "lo_lseek"))
@ -631,7 +681,7 @@ lo_initialize(PGconn *conn)
/*
* Finally check that we really got all large object interface
* functions.
* functions --- except lo_create, which may not exist.
*/
if (lobjfuncs->fn_lo_open == 0)
{