{"id":200872,"date":"2024-11-21T02:05:48","date_gmt":"2024-11-21T02:05:48","guid":{"rendered":"https:\/\/namso-gen.co\/blog\/how-to-change-plan-hash-value-in-oracle\/"},"modified":"2024-11-21T02:05:48","modified_gmt":"2024-11-21T02:05:48","slug":"how-to-change-plan-hash-value-in-oracle","status":"publish","type":"post","link":"https:\/\/namso-gen.co\/blog\/how-to-change-plan-hash-value-in-oracle\/","title":{"rendered":"How to change PLAN HASH value in Oracle?"},"content":{"rendered":"

In Oracle, the PLAN HASH value is a unique identifier used to represent a specific execution plan for a SQL statement. It is calculated based on the contents of the execution plan and is used by the query optimizer to determine if a cached plan can be reused. Changing the PLAN HASH value in Oracle can be useful in situations where you want to force Oracle to generate a new execution plan for a particular SQL statement.<\/p>\n

One way to change the PLAN HASH value in Oracle is to use the DBMS shared pool package. By altering the SQL statement slightly, you can force Oracle to recalculate the PLAN HASH value and generate a new execution plan. Here’s how you can do it:<\/p>\n

1. Query the current PLAN HASH value for the SQL statement you want to change:
\n“`sql
\nSELECT PHV, ADDRESS
\nFROM V$SQL
\nWHERE SQL_ID = ‘your_sql_id’;
\n“`<\/p>\n

2. Use the DBMS shared pool package to flush the SQL statement from the shared pool:
\n“`sql
\nDECLARE
\n l_address VARCHAR2(16);
\nBEGIN
\n SELECT ADDRESS INTO l_address
\n FROM V$SQL
\n WHERE SQL_ID = ‘your_sql_id’;
\n DBMS_SHARED_POOL.PURGE(l_address, ‘C’);
\nEND;
\n“`<\/p>\n

3. Execute the SQL statement again to force Oracle to generate a new execution plan:
\n“`sql
\nSELECT * FROM your_table WHERE your_condition;
\n“`<\/p>\n

4. Query the new PLAN HASH value to verify that it has changed:
\n“`sql
\nSELECT PHV
\nFROM V$SQL
\nWHERE SQL_ID = ‘your_sql_id’;
\n“`<\/p>\n

By following these steps, you can effectively change the PLAN HASH value in Oracle and force the query optimizer to generate a new execution plan for a SQL statement.<\/p>\n

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