Index usage is categorized into buckets of different ranges. Each bucket has a range of values for access count and rows returned. An entry is placed into a bucket if the rows returned or access counts falls within the range of that bucket. The first report is the Index Usage Statistics report, that consists of two parts; the Index Usage Statistics report that shows statistics about the number of Scans, Seeks, Updates and Lookups with the latest date for each operation, that is retrieved by querying the sys.dm_db_index_usage_stats DMV, 2) it is possible for Oracle to use the statistics (specifically num_distinct) from an index to help pick an execution plan without actually using the index in the plan. On top of Richard's suggestion another INDICATOR or redundancy is to find indexes where one index is the leading set of columns of another index IN THE SAME ORDER. You can still locate unused indexes in Oracle and Oracle 8i, but the mechanism for finding the unused indexes is not as easy. Finding unused indexes on Oracle One of the great features of Oracleis the ability to easily locate and remove unused indexes. Look to remove the index once you have confirmed that the values are not skewed by a server restart that has wiped out details of a high usage period. The index might be specifically there to support a monthly, quarterly or even annual data analysis and could cause huge problems if it is missing. I am trying to gather usage statistics for a large Oracle database. I know about looking at the DBA_TAB_MODIFICATIONS view to see INSERT, UPDATE, and DELETE stats. But what about just select state Gather statistics on the indexes for this table. Index statistics gathering is not parallelized. Using this option is equivalent to running the GATHER_INDEX_STATS Procedure on each of the table's indexes. Use the constant DBMS_STATS.AUTO_CASCADE to have Oracle determine whether index statistics to be collected or not. This is the default.
I am trying to gather usage statistics for a large Oracle database. I know about looking at the DBA_TAB_MODIFICATIONS view to see INSERT, UPDATE, and DELETE stats. But what about just select state Gather statistics on the indexes for this table. Index statistics gathering is not parallelized. Using this option is equivalent to running the GATHER_INDEX_STATS Procedure on each of the table's indexes. Use the constant DBMS_STATS.AUTO_CASCADE to have Oracle determine whether index statistics to be collected or not. This is the default. DBA_FEATURE_USAGE_STATISTICS. Extents of locally managed tablespaces are managed automatically by Oracle. Automatic Segment Space Management (user) There is at least one usage of the Oracle Spatial index metadata table. SQL Access Advisor. A task for SQL Access Advisor has been executed.
Also see my notes on detecting duplicate Oracle index columns and how to detect duplicate table rows. In Oracle10g, it is easy to see what indexes are used, when they are used and the context in which they stats$sql_plan_usage spu. 17 Jul 2018 To check if the index has been used, will depends on the version of Oracle: dynamic statistics used: dynamic sampling (level=2) Statistics
Should I create script that will gather stats for one index at a time ?Yes, unless you want to gather stats for all indexes on a table, in which case you can use dbms_stats.gather_table_stats with the argument cascade being true. And if you want all tables in a schema, you'll be using dbms_stats.gather_schema_stats.
17 Jul 2018 To check if the index has been used, will depends on the version of Oracle: dynamic statistics used: dynamic sampling (level=2) Statistics 25 Jul 2017 DBA_INDEX_USAGE: DBA_INDEX_USAGE displays cumulative statistics for each index. With these two new views, Oracle automatically