Collect Statistics analyzes the contents of tables. When you analyze a table, the database collects statistics about expressions occurring in any function-based indexes as well. Therefore, be sure to create function-based indexes on the table before analyzing the table.
Oracle Database collects the following statistics for a table. Statistics marked with an asterisk (*) are always computed exactly.
NUM_ROWS | Number of rows. |
* BLOCKS | Number of data blocks below the high water mark - the number of data blocks that have been formatted to receive data, regardless whether they currently contain data or are empty. |
* EMPTY_BLOCKS | Number of data blocks allocated to the table that have never been used. |
AVG_SPACE | Average available free space in each data block in bytes. |
CHAIN_COUNT | Number of chained rows. |
AVG_ROW_LEN | Average row length, including the row overhead, in bytes. |