HOW TO
To improve performance and reduce physical I/O operations, it is recommended that the block_data column's LOB segment be set to CACHED.
Instructions provided show how to alter a raster block table's LOB segment from NOCACHE to CACHE. If a raster block table's block_data column is created without specifying the storage options for the LOB segment, Oracle's default setting is NOCACHE, meaning LOB values are not brought into the buffer cache.
Code:
SQL> SELECT table_name, cache
2 FROM user_lobs
3 WHERE column_name = 'BLOCK_DATA'
4 AND cache = 'NO';
TABLE_NAME CACHE
----------------------- -------
SDE_BLK_20 NO
Code:
SQL> ALTER TABLE sde_blk_20
2 MODIFY LOB (block_data)(CACHE);
Table altered.
SQL> SELECT table_name, cache
2 FROM user_lobs
3 WHERE column_name = 'BLOCK_DATA'
4 AND table_name = 'SDE_BLK_20';
TABLE_NAME CACHE
----------------------- -------
SDE_BLK_20 YES
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