I will explain dbms_stats.gather_table_stats tips in Oracle in this post.
dbms_stats.gather_table_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 to date in Oracle database for Oracle optimizer. Because Oracle optimizer uses database statistics to generate lots of execution plans in same time and If statistics are up to date ,then Optimizer decide correct execution plans.
Gather Table Stats
Syntax of gather_table_stats is as follows.
DBMS_STATS.GATHER_TABLE_STATS (
ownname VARCHAR2,
tabname VARCHAR2,
partname VARCHAR2 DEFAULT NULL,
estimate_percent NUMBER DEFAULT to_estimate_percent_type
(get_param('ESTIMATE_PERCENT')),
block_sample BOOLEAN DEFAULT FALSE,
method_opt VARCHAR2 DEFAULT get_param('METHOD_OPT'),
degree NUMBER DEFAULT to_degree_type(get_param('DEGREE')),
granularity VARCHAR2 DEFAULT GET_PARAM('GRANULARITY'),
cascade BOOLEAN DEFAULT to_cascade_type(get_param('CASCADE')),
stattab VARCHAR2 DEFAULT NULL,
statid VARCHAR2 DEFAULT NULL,
statown VARCHAR2 DEFAULT NULL,
no_invalidate BOOLEAN DEFAULT to_no_invalidate_type (
get_param('NO_INVALIDATE')),
force BOOLEAN DEFAULT FALSE);
EXEC DBMS_STATS.GATHER_TABLE_STATS('SCHEMA_OWNER', 'TABLE_NAME', method_opt => 'FOR COLUMNS (empno, deptno)');
To gather table stats, use following script.
EXEC DBMS_STATS.gather_table_stats('MEHMET', 'DEVECI', estimate_percent => 25, cascade => TRUE);
Read the following post to learn more details about DBMS_STATS.
Do you want to learn Oracle Database for Beginners, then read the following articles.
https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/