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How to Quickly Enumerate Indexes in Oracle 11gR2

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How to Quickly Enumerate Indexes in Oracle 11gR2

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:

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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:

SELECT
  i.index_name,
  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 run 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
-------------------------------------------
IDX_FK_FILM_ACTOR_ACTOR   ACTOR_ID
IDX_FK_FILM_ACTOR_FILM    FILM_ID
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.

Learn how to get 20x more performance than Elastic by moving to a Time Series database.

Topics:
11gr2 ,oracle ,sql ,listagg

Published at DZone with permission of Lukas Eder, DZone MVB. See the original article here.

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