Hitachi

Hitachi Advanced Database Setup and Operation Guide


11.3.6 Checking a range index (whether it can skip chunks)

This subsection explains how to check whether a defined range index can skip chunks.

Note

Range indexes defined in versions earlier than 02-02 cannot skip chunks.

By searching the IS_CHUNK_SKIP column of the SQL_INDEXES dictionary table, you can determine whether a range index can skip chunks. The following shows a SELECT statement specification example:

SELECT statement specification example
SELECT "TABLE_SCHEMA","TABLE_NAME","INDEX_NAME","IS_CHUNK_SKIP"
  FROM "MASTER"."SQL_INDEXES" WHERE "INDEX_TYPE" = 'R'

If the IS_CHUNK_SKIP column in the search result is Y, the range index can skip chunks. If the IS_CHUNK_SKIP column is the null value, the range index cannot skip chunks.

To change a range index that cannot skip chunks into one that can skip chunks, see 11.3.7 Redefining a range index (setting up chunk skipping).

For details about dictionary table SQL_INDEXES, see B.5 Content of SQL_INDEXES.

Note

If you know the schema name and index identifier of the range index in question, you can also perform a search based on the explanation in (19) When checking whether the index is a range index that can skip chunks under B.22 Searching a dictionary table.