What is selectivity? Selectivity is the estimated proportion of the rows that will return from our query based on the total rows of that table.…
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Enable or Disable Table Locks in Oracle Database
Table Locks are an important part of Oracle Working Mechanism as they provide security from unwanted deletion or modification of table’s data which can sometimes…
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Column Histograms in Oracle 11g
Data skew in a column can make it difficult for the optimizer to accurately estimate the cardinality of an operation. Without a histogram it will…
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Oracle Text Index
With Oracle text indexes (or Domain index), we can index text documents and search it based on contents using text patterns with specialized text query operators. Oracle…
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Export Import statistics with dbms_stats in Oracle
You can use the Oracle dbms_stats and export utilities to migrate schema statistics from your PROD instance to your TEST instance, so that your developers…
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Oracle Version Numbers
Something that always comes up when discussing Oracle versions is that I am not always sure which number is the Major Database Release and which is the Database…
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Find password for database link (<= 11.2.0.2)!
when we need to recreate a database link for some reason and we do not happen to have the password handy, weβre usually stuck. However,…
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How to check progress of a long running statistics gathering job
If you have a long-running statistics job running, you can check it from v$session_longops: For example, you execute: Check progress with:
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Gather Schema Stats using DBMS_STATS.GATHER_SCHEMA_STATS
DBMS_STATS package was introduced in Oracle 8i and used to gather Database,table,Schema,dictionary and fixed object statistic in Oracle database. Statistic of objects should be up…
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