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How to Quickly Enumerate Indexes in Oracle 11gR2

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How to Quickly Enumerate Indexes in Oracle 11gR2

How to discover what kind of indexes there are on any given table in an Oracle schema.

· Database Zone ·
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Do you want to know real quick what kind of indexes there are on any given table in your Oracle schema? Nothing simpler than that. Just run the following query:

  listagg(c.column_name, ', ') 
    WITHIN GROUP (ORDER BY c.column_position)
    AS columns
FROM all_indexes i
JOIN all_ind_columns c 
  ON i.index_name = c.index_name
WHERE i.table_name = 'FILM_ACTOR'
GROUP BY i.index_name

The above query is ran against the Sakila database. Just replace the “FILM_ACTOR” table by your table and you’re all set. The result looks like:

INDEX_NAME                COLUMNS
SYS_C007155               ACTOR_ID, FILM_ID

Sometimes, it’s the simple things…

Explanation about LISTAGG

LISTAGG is a so-called ordered-set aggregate function, added in 11gR2, i.e. the aggregate function will aggregate the data “WITHIN a GROUP” given a specific “ORDER”. This is obviously useful for string concatenation, but it can be very useful also for a variety of other functions, such as inverse distribution functions, such as the MEDIAN, which we’ve blogged about here.

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