Below section I have tried to present all the important features in Oracle Database management
What is PREFERENCE_OVERRIDES_PARAMETER We discussed optimizer statistics preferences in the previous blog post and we know that that got overwritten by the values given explicitly in the dbms_stats procedure Oracle Database 12 Release 2 includes a new DBMS_STATS preference called PREFERENCE_OVERRIDES_PARAMETER When this preference is set to TRUE, it allows preference settings to override DBMS_STATS …
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Sometimes we may have performance issues and we want to check the optimizer statistics preferences at the table level. let’s check out the queries for that How to check optimizer stats preferences at the table level set pages 200 lines 200col owner for a16col table_name for a32col preference_value for a50select owner, table_name, PREFERENCE_NAME, PREFERENCE_VALUEfrom dba_tab_stat_prefswhere …
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What are optimizer statistics preferences? The statistics preferences of the optimizer determine the preset values of the parameters used by automatic statistics collection and the DBMS_STATS statistics gathering processes. We can configure optimizer information at the table, schema, database (all tables), and global levels. A global preference refers to tables with no preferences as well …
When we ran gather stats on the table, it generate table stats, index stats, and column stats. Column statistics are used in the optimizer’s selectivity calculations Let’s see how to find it How to check column statistics in Oracle Column stats can be found from dba_tab_columns or dba_tab_col_statistics SELECT column_name, num_distinct, density, num_nulls, avg_col_len, num_buckets, …
Indexes are used to fasten access to the record in Oracle. Optimizer chooses an index over a full table scan based on the Index statistics. The statistics allow the optimizer to calculate the effectiveness of using one index over another. Let’s check out how to find the index statistics How to check Index statistics for …
Many times, we might want to check if gather stats ran on the table and when it ran last time. We can find this query dba_tables or user_tables view. let’s see a few queries related to this How to check gather stats on a table/how to check last gather stats on table in Oracle The …
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