OPEN Procedure

This procedure opens a LOB, internal or external, in the indicated mode. Valid modes include read-only, and read-write. It is an error to open the same LOB twice.

Note: If the LOB was opened in read-only mode, and if you try to write to the LOB, then an error is returned. BFILE can only be opened with read-only mode.

In Oracle8.0, the constant file_readonly was the only valid mode in which to open a BFILE. For Oracle 8i, two new constants have been added to the DBMS_LOB package: lob_readonly and lob_readwrite.

Syntax

DBMS_LOB.OPEN (
   lob_loc   IN OUT NOCOPY BLOB,
   open_mode IN            BINARY_INTEGER);
 
DBMS_LOB.OPEN (
   lob_loc   IN OUT NOCOPY CLOB CHARACTER SET ANY_CS,
   open_mode IN            BINARY_INTEGER);
 
DBMS_LOB.OPEN (
   file_loc  IN OUT NOCOPY BFILE,
   open_mode IN            BINARY_INTEGER := file_readonly);

Parameters

Table 22-36 OPEN Procedure Parameters

Parameter	Description
lob_loc	LOB locator.
open_mode	Mode in which to open.

Usage Notes

OPEN requires a round-trip to the server for both internal and external LOBs. For internal LOBs, OPEN triggers other code that relies on the OPEN call. For external LOBs (BFILEs), OPEN requires a round-trip because the actual operating system file on the server side is being opened.

It is not mandatory that you wrap all LOB operations inside the Open/Close APIs. However, if you open a LOB, you must close it before you commit or rollback the transaction; an error is produced if you do not. When an internal LOB is closed, it updates the functional and domain indexes on the LOB column.

It is an error to commit the transaction before closing all opened LOBs that were opened by the transaction. When the error is returned, the openness of the open LOBs is discarded, but the transaction is successfully committed. Hence, all the changes made to the LOB and nonLOB data in the transaction are committed, but the domain and functional indexes are not updated. If this happens, you should rebuild the functional and domain indexes on the LOB column.