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Finding Direct Indexes

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If you’re not using Toad DBA Suite, it’s sometimes hard to find solutions. Somebody wanted to know how to find indexes that aren’t indirect. Indirect indexes are those created for a primary key because a primary key column or set of columns are both not null and uniquely constrained. Likewise, you create a unique index when you can create a unique constraint. You can’t drop a unique index for a primary key without dropping the primary key or unique constraint that indirectly created it.

The following query returns indexes with one or more columns that are created by a CREATE INDEX statement on a target table. It excludes unique indexes created by a primary key constraint, and it returns the relative position of columns in an index:

COLUMN sequence_name   FORMAT A22 HEADING "Sequence Name"
COLUMN column_position FORMAT 999 HEADING "Column|Position"
COLUMN column_name     FORMAT A22 HEADING "Column|Name"
SELECT   uin.index_name
,        uic.column_position
,        uic.column_name
FROM     user_indexes uin INNER JOIN user_ind_columns uic
ON       uin.index_name = uic.index_name
AND      uin.table_name = uic.table_name
WHERE    uin.table_name = UPPER('&&table_name')
AND NOT  uin.index_name IN (SELECT constraint_name
                            FROM   user_constraints
                            WHERE  table_name = UPPER('&&table_name'))
ORDER BY uin.index_name
,        uic.column_position;

It can be rewritten into a function, which can then drop indexes based on a table name:

( pv_table_name  VARCHAR2 ) RETURN NUMBER IS 
  /* A return value. */
  lv_return  NUMBER := 0;
  /* A query to return only directly created indexes. */
  CURSOR find_indexes_on
  ( cv_table_name  VARCHAR2 ) IS
    SELECT   DISTINCT ui.index_name
    FROM     user_indexes ui INNER JOIN user_ind_columns uic
    ON       ui.index_name = uic.index_name
    AND      ui.table_name = uic.table_name
    WHERE    ui.table_name = UPPER(cv_table_name)
    AND NOT  ui.index_name IN (SELECT constraint_name
                               FROM   user_constraints
                               WHERE  table_name = UPPER(cv_table_name));
  /* Declare function autonomous. */
  /* Drop the indexes on a table. */
  FOR i IN find_indexes_on(pv_table_name) LOOP
    EXECUTE IMMEDIATE 'DROP INDEX '||i.index_name;
    lv_return := 1;
  RETURN lv_return;
END drop_indexes_on;

You can call the drop_on_indexes_on function like this:

SELECT   drop_indexes_on(UPPER('address_lab'))
FROM     dual;

Hope this helps those who need to work with dropping indexes.

Written by maclochlainn

November 23rd, 2014 at 8:42 pm