alter session set hash_area_size : Session variable « SQL Plus « Oracle PL / SQL






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

alter session set hash_area_size

    
SQL> create table myTable
  2  as
  3  select rownum id, a.*
  4    from all_objects a
  5   where 1=0
  6  /
SQL>
SQL>
SQL>
SQL> set autotrace traceonly explain
SQL>
SQL> alter session set sort_area_size = 102400000;
SQL>
SQL> alter session set hash_area_size = 204800000;
SQL>
SQL> select a.object_type, b.object_name
  2    from myTable a, myTable b
  3   where a.last_ddl_time = b.last_ddl_time;

Execution Plan
----------------------------------------------------------
Plan hash value: 2666611345

--------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost  |
--------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |    67 |  3082 |     3 |
|*  1 |  HASH JOIN         |         |    67 |  3082 |     3 |
|   2 |   TABLE ACCESS FULL| MYTABLE |    82 |  1640 |     1 |
|   3 |   TABLE ACCESS FULL| MYTABLE |    82 |  2132 |     1 |
--------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - access("A"."LAST_DDL_TIME"="B"."LAST_DDL_TIME")

Note
-----
   - cpu costing is off (consider enabling it)

SQL>
SQL> alter session set sort_area_size = 65536;
SQL>
SQL> alter session set hash_area_size = 131072;
SQL>
SQL> select a.object_type, b.object_name
  2    from myTable a, myTable b
  3   where a.last_ddl_time = b.last_ddl_time;

Execution Plan
----------------------------------------------------------
Plan hash value: 2666611345

--------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost  |
--------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |    67 |  3082 |     3 |
|*  1 |  HASH JOIN         |         |    67 |  3082 |     3 |
|   2 |   TABLE ACCESS FULL| MYTABLE |    82 |  1640 |     1 |
|   3 |   TABLE ACCESS FULL| MYTABLE |    82 |  2132 |     1 |
--------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - access("A"."LAST_DDL_TIME"="B"."LAST_DDL_TIME")

Note
-----
   - cpu costing is off (consider enabling it)

SQL>
SQL> set autotrace off
SQL>
SQL>
SQL> drop table myTable;








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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';
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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
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8.event-based call and exception tracing.
9.SQL trace
10.uses dynamic SQL to issue an ALTER SESSION statement.
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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
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20.interaction between ALTER SESSION and autonomous transactions.
21.ALTER SESSION SET SQL_TRACE = TRUE
22.ALTER SESSION SET optimizer_dynamic_sampling
23.alter session set NLS_DATE_FORMAT='DD-MM-YYYY'
24.alter session set current_schema=Smart
25.alter session set db_file_multiblock_read_count
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: