ALTER SESSION SET optimizer_dynamic_sampling : Session variable « SQL Plus « Oracle PL / SQL






  1. Oracle PL / SQL
  2. SQL Plus
  3. Session variable

ALTER SESSION SET optimizer_dynamic_sampling

    

SQL>
SQL> ALTER SESSION SET optimizer_dynamic_sampling = 0;

Session altered.

SQL>
SQL>
SQL> CREATE TABLE myTable AS SELECT * FROM all_objects;

Table created.

SQL>
SQL>
SQL> CREATE TABLE myTable2 AS SELECT object_id, object_name FROM myTable;

Table created.

SQL>
SQL> ALTER TABLE myTable2 ADD object_application VARCHAR2(12);

Table altered.

SQL>
SQL> UPDATE myTable2 SET object_application = 'WORKSHOP';

12597 rows updated.

SQL>
SQL> COMMIT;

Commit complete.

SQL>
SQL> SET AUTOTRACE TRACEONLY EXPLAIN;
SQL>
SQL>
SQL> ALTER SESSION SET optimizer_dynamic_sampling = 1;

Session altered.

SQL>
SQL>
SQL> SET AUTOTRACE OFF;
SQL>
SQL> DROP TABLE myTable2;

Table dropped.

SQL>
SQL> DROP TABLE myTable;

Table dropped.

SQL>








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1.alter the session with the ALTER SESSION statement and set the session's time zone forward
2.alter session set nls_date_format = 'dd-MON-yyyy hh24:mi:ss';
3.alter session set OPTIMIZER_MODE = RULE
4.Adjust your session time zone to -08:00, display the contents of your time table.
5.alter session set cursor_sharing = force
6.alter session set use_stored_outlines
7.Event-based call and exception tracing
8.event-based call and exception tracing.
9.SQL trace
10.uses dynamic SQL to issue an ALTER SESSION statement.
11.ALTER SESSION SET QUERY_REWRITE_ENABLED
12.alter session set sql_trace=true
13.sql_trace a stored procedure
14.Set the following session parameters to enable query rewrite:
15.If your session time zone is not US/Central (-06:00), alter your session to Central time:
16.alter session set nls_date_format = 'DD-MON-YYYY HH24:MI:SS'
17.Alter time_zone
18.sessiontimezone, current_timestamp
19.demonstrates the use of DBMS_SQL to execute an ALTER SESSION statement.
20.interaction between ALTER SESSION and autonomous transactions.
21.ALTER SESSION SET SQL_TRACE = TRUE
22.alter session set NLS_DATE_FORMAT='DD-MM-YYYY'
23.alter session set current_schema=Smart
24.alter session set db_file_multiblock_read_count
25.alter session set hash_area_size
26.alter session set nls_date_format='dd-mm-yyyy', nls_language=Dutch, nls_currency='Eur'
27.alter session set optimizer_index_cost_adj, alter session set optimizer_index_caching
28.alter session set optimizer_max_permutations=80000
29.alter session set optimizer_mode=all_rows
30.alter session set optimizer_mode=first_rows
31.alter session set query_rewrite_integrity=enforced
32.alter session set sort_area_size = 102400000
33.alter session set workarea_size_policy=manual
34.alter system flush shared_pool
35.alter system quiesce restricted
36.alter system resume
37.alter system suspend
38.set optimizer_features_enable = '8.1.5' scope = spfile
39.show filestat
40.show parameter optimizer_features
41.show verify
42.If your session time zone is not US/Central Standard Time (-06:00), alter your session to Central Standard time: