What are the BIN$... tables in Oracle's ALL_TAB_COLUMNS table?

When I query ALL_TAB_COLUMNS in Oracle, I see tables called

BIN$frKctA83wMPgQEOSh0Az+A==$0
BIN$frKctA8cwMPgQEOSh0Az+A==$0
BIN$frQ1pdU2TgXgQEOSh0APxA==$0
BIN$frQ1pdVGTgXgQEOSh0APxA==$0

There is no corresponding entry in ALL_TABLES. What are those开发者_开发技巧?

Since version 10g, dropped tables (also dropped objects in general) are put in the recycle bin and can be restored easily. The names you see are tables in the recycle bin.

You can bypass the recycle bin by adding the PURGE keyword in your DROP statements.

You will find additional information in the Administrator's Guide Documentation.