Adaptive Cursor Sharing

Adaptive Cursor Sharing:   This document will explain step by step to analyze adaptive cursor sharing. Let’s start with the basics. Let’s create a table as a copy of dba_objects.   SQL> create table t as select * from dba_objects; Now, if we run a query like ‘select object_name from t where object_id=1027’, then it must go through the full […]

Comparison between exadata and non-exadata executions test case

First we need to load data SQL> alter session set tracefile_identifier=’ABC’; Session altered. Elapsed: 00:00:00.01 SQL> alter system set events ‘10046 trace name context forever, level 12′; System altered. Elapsed: 00:00:00.18 SQL> create table t1(c1 number,c2 char(2000)); Table created. Elapsed: 00:00:00.03 SQL> set autotrace on; SQL> set autotrace traceonly; SQL> insert into t1 select rownum,’A’ from dual connect by rownum<100000; […]

Oracle 12c gather statistics oracle deep dive

I referred some reference from my favorite Tim Hall blog (ORACLE_BASE) A.Basic of optimizer statistics: – The optimizer cost model relies on statistics collected about the objects involved in a query, and the database and host where the query runs. Statistics are critical to the optimizer’s ability to pick the best execution plan for a SQL statement. Object What influences […]