Statistics
How to lock or unlock table statistics in Oracle
Lock a table statistics so gathering skips it, or unlock to resume normal gathering, with DBMS_STATS.LOCK_TABLE_STATS.
How to restore table statistics to an earlier time in Oracle
Roll a table statistics back to an earlier version with DBMS_STATS.RESTORE_TABLE_STATS, the quickest fix when fresh stats caused a bad plan.
How to gather dictionary and fixed object statistics in Oracle
Refresh data dictionary and fixed object (X$/V$) statistics with DBMS_STATS, recommended after big changes or an upgrade.
How to delete table statistics in Oracle
Delete the optimizer statistics on a table with DBMS_STATS.DELETE_TABLE_STATS, with a note on why locking is usually safer.
How to gather statistics for a schema in Oracle
Gather optimizer statistics for every object in a schema with DBMS_STATS.GATHER_SCHEMA_STATS, using GATHER AUTO to refresh only stale data.
How to gather statistics on a table in Oracle
Gather fresh optimizer statistics for a table and its indexes with DBMS_STATS.GATHER_TABLE_STATS, then verify the new row count.
How to check optimizer statistics on a table in Oracle
Check a table optimizer statistics: row count, blocks, sample size, when they were last gathered, and whether they are locked.
How to find tables with stale optimizer statistics in Oracle
List Oracle tables, partitions, and subpartitions whose optimizer statistics are marked stale in DBA_TAB_STATISTICS.