To use value compression, you must have a license for the DB2 Storage Optimization Feature.

Value compression uses a page-level dictionary-based compression algorithm to compress data based on repetition of values found in a single column.

Value compression involves removing duplicate entries for a value, only storing one copy, and keeping track of the location of any references to the stored copy.

When value compression is used, the byte count of compressed NULLs, zeros, and blanks might be larger than that of the uncompressed version of the same

Page-level dictionaries are stored in hidden rows within the table.

Table-level dictionaries are stored in hidden rows within the table.

Page-level dictionaries are automatically created or recreated by the database manager as pages are filled.

Table-level dictionaries are automatically created or recreated as by the database manager as pages are filled.

They improve the performance of sequential prefetching by reading contiguous pages from disk and writing them into contiguous pages in a buffer pool.

They improve the performance of random I/O by reading non-contiguous pages from disk and writing them into near-contiguous free space in a buffer pool.

They improve the performance of vectored reads by retrieving non-contiguous pages from disk, combining them into extent-sized blocks, and writing the blocks into contiguous pages in a buffer pool.

They improve the performance of scattered writes by retrieving non-contiguous pages from a buffer pool, combining them into extent-sized blocks, and writing

CREATE INDEX sales_idx ON sales (region)

CREATE INDEX sales_idx ON sales (sales_person)

CREATE INDEX sales_idx ON sales (region, sales_person)

CREATE INDEX sales_idx ON sales (region) INCLUDE (sales_person)

The MON_DB_SUMMARY administrative view.

The MON_BP_UTILIZATION administrative view.

The MON_GET_ACTIVITY_DETAILS table function.

The MON_GET_EXTENT_MOVEMENT_STATUS table function.