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The Flashback Drop feature is automatically enabled in an Oracle Database 10g database. You don t have to configure a thing in order to use the feature.

In summary, on issuing a DROP TABLE (or DROP INDEX) command in Oracle Database 10g, the objects in question are not truly dropped. Oracle simply hides them, and you can restore them at a later point using Flashback Drop. If you truly do want to permanently remove an object, you can use the PURGE option with the DROP command: SQL> DROP TABLE test PURGE; Let s take a look at all this in a bit more detail.

As mentioned earlier, the Recycle Bin is a logical structure a data dictionary table named RECYCLEBIN$. You can view the contents of the Recycle Bin for the currently logged in user via the USER_RECYCLEBIN view (RECYCLEBIN is a synonym for USER_RECYCLEBIN). Alternatively, you can view the contents of the Recycle Bin for the entire database via the DBA_RECYCLEBIN view. The following code shows an example of the latter: SQL> SELECT owner, original_name, object_name, ts_name, droptime FROM dba_recyclebin; OWNER ORIGINAL_NAME OBJECT_NAME TS_NAME ---------------------------------------------------------------------sam PERSONS BIN$xTMPjHZ6SG+1xnDIaR9E+g==$0 USERS At the user level, you simply select from the RECYCLEBIN view, instead of the DBA_RECYCLEBIN view. You can also use the SHOW RECYCLEBIN command from SQL*Plus: SQL> SHOW RECYCLEBIN ORIGINAL NAME RECYCLEBIN NAME OBJECT TYPE DROP TIME ---------------- ------------------------------ ------------ ------------------LOGIN_INFO BIN$5oAI+vnANcTgNABgsLLCaA==$0 TABLE 2005-06-29:15:48:31 TEST5 BIN$+rR0/h2APITgNABgsLLCaA==$0 TABLE 2005-06-29:15:44:53 SQL>

The CAN_UNDROP and CAN_PURGE columns of the DBA_RECYCLEBIN view tell you whether you can undrop and purge an object, respectively. The SHOW RECYCLEBIN command shows only those objects that you can undrop.

As you can see, when a table is moved to the Recycle Bin, Oracle assigns it a system-generated name, which is usually 30 characters long. If you wish to query an object in the Recycle Bin, you must use its new system-generated name, enclosed in double quotes: SQL> SELECT * FROM "BIN$xTMPjHZ6SG+1xnDIaR9E+g==$0"; NAME -------------------valerie alapati sam alapati nina alapati nicholas alapati shannon alapati SQL>

Oracle renames all objects in the Recycle Bin, including any dependent objects such as indexes, constraints, and triggers. When you recover a table, Oracle will recover the dependent objects as well, but they ll retain these cryptic system-generated names, so you will need to rename them appropriately. In order to find out which of your tables are currently in the Recycle Bin, you can simply query the DBA_TABLES view. A table that was dropped and is in the Recycle Bin will show a YES value for the DROPPED column, and NO otherwise.

You can restore any dropped table, as long as it is still listed in the Recycle Bin, by using the FLASHBACK TABLE table_name TO BEFORE DROP command (at which point Oracle will also remove it from the Recycle Bin). The following example would restore the previously dropped persons table. SQL> FLASHBACK TABLE persons TO BEFORE DROP; Flashback complete. SQL> Alternatively, you can use the system-generated table name: SQL> FLASHBACK TABLE "BIN$xTMPjHZ6SG+1xnDIaR9E+g==$0" TO BEFORE DROP; Flashback complete. SQL> As part of the Flashback operation, you may want to rename the previously dropped table, as follows (you can use either the system-generated or original table name): SQL> FLASHBACK TABLE "BIN$xTMPjHZ6SG+1xnDIaR9E+g==$0" TO BEFORE DROP RENAME TO NEW_PERSONS; This is particularly useful when you ve already created a new table with the same name as the dropped table. If you drop a table and then create a new one of the same name, it s possible (if you then drop that new table) that the Recycle Bin will contain several versions of the dropped table, each with a unique system-generated table name. If you then issue a FLASHBACK TABLE . . . TO BEFORE DROP command using the original table name, Oracle will simply recover the latest version of the table. If you want to return to an older version you can then simply reissue the same command until you recover the required version. Alternatively, you can provide the specific system-generated name of the table you want to recover.