Hi,
Oracle Spatial index creates MDRT tables and related MDRS sequences , are these MDRS sequences related to these SDO indexes?
The MDRT_<>$ tables (and the associated MDRS_<>$ sequences) are used to store information for spatial indexes.
These tables have the following caveats:
•You should not move the MDRT tables from one tablespace to another: If you do, the corresponding spatial index becomes unusable, and all spatial operators on the indexed table fail. You can specify the tablespace in which the MDRT table needs to be stored using the tablespace parameter during spatial index creation.
•You should not drop or alter the MDRT tables or the MDRS sequences: You can drop them, however, if they are not associated with any spatial index (this should not happen under normal circumstances). You can identify all MDRT tables that are associated with the user’s spatial indexes by inspecting the USER_SDO_INDEX_METADATA view:
SQL> SELECT sdo_index_name, sdo_index_table, sdo_rtree_seq_name FROM USER_SDO_INDEX_METADATA;
•You should not export the MDRT tables explicitly. Upon import the tables are created when the Spatial index for a table is created.
•You should not replicate the MDRT tables to a replicated database.
Talip Hakan Ozturk's ORACLE BLOG 