这篇文章主要介绍了数据库中如何验证SQL ID与SQL HASH VALUE转换,具有一定借鉴价值,感兴趣的朋友可以参考下,希望大家阅读完这篇文章之后大有收获,下面让小编带着大家一起了解一下。

实验目的:验证SQL ID与SQL HASH VALUE转换

SQL> set linesize 1000

SQL> select count(1) from tab_01;

COUNT(1)

----------

85128

SQL> select * from table(dbms_xplan.display_cursor( null,null,'advanced'));

PLAN_TABLE_OUTPUT

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

SQL_ID6mhbq2s7z9ydn, child number 0

-------------------------------------

select count(1) from tab_01

Plan hash value: 4218700832

---------------------------------------------------------------------

| Id| Operation| Name| Rows| Cost (%CPU)| Time|

---------------------------------------------------------------------

|0 | SELECT STATEMENT|||342 (100)||

|1 |SORT AGGREGATE||1 |||

PLAN_TABLE_OUTPUT

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|2 |TABLE ACCESS FULL| TAB_01 | 85128 |342(1)| 00:00:01 |

---------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):

-------------------------------------------------------------

1 - SEL$1

2 - SEL$1 / TAB_01@SEL$1

Outline Data

-------------

PLAN_TABLE_OUTPUT

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

/*+

BEGIN_OUTLINE_DATA

IGNORE_OPTIM_EMBEDDED_HINTS

OPTIMIZER_FEATURES_ENABLE('11.2.0.4')

DB_VERSION('11.2.0.4')

ALL_ROWS

OUTLINE_LEAF(@"SEL$1")

FULL(@"SEL$1" "TAB_01"@"SEL$1")

END_OUTLINE_DATA

*/

PLAN_TABLE_OUTPUT

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Column Projection Information (identified by operation id):

-----------------------------------------------------------

1 - (#keys=0) COUNT(*)[22]

已选择39行。

SQL> select sql_text,sql_id,hash_value,child_number from v$sql where sql_text like 'select count(1) from tab_01%';

SQL_TEXT

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

SQL_IDHASH_VALUE CHILD_NUMBER

-------------------------- ---------- ------------

select count(1) from tab_01

6mhbq2s7z9ydn2677129480

SQL> select lower(trim('6mhbq2s7z9ydn')) sql_id,trunc(mod(sum((instr('0123456789abcdfghjkmnpqrstuvwxyz',substr(lower(trim('6mhbq2s7z9ydn ')), level, 1)) - 1) *

2 power(32, length(trim('6mhbq2s7z9ydn ')) - level)),power(2, 32))) hash_valuefrom dual connect by level <= length(trim('6mhbq2s7z9ydn'));

SQL_IDHASH_VALUE

-------------------------- ----------

6mhbq2s7z9ydn267712948

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