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-- #############################################################################################---- %Purpose: Flush Shared Pool when it reaches 60-70% of it's capacity---- Use: SYS-User---- #############################################################################################---- On a recent project we had a problem where performance would start-- acceptable at the beginning of the day and by mid-day would be-- totally unacceptable. Investigation showed that the third party-- application that ran on top of the Oracle database was generating-- ad hoc SQL without using bind variables. This generation of ad hoc-- SQL and non-use of bind variables was resulting in proliferation of-- non-reusable code fragments in the shared pool, one user had over-- 90 shared pool segments assigned for queries that differed only by-- the selection parameter (for example "where last_name='SMITH'"-- instead of "where last_name='JONES'"). This proliferation of multiple-- nearly identical SQL statements meant that for each query issued-- the time to scan the shared pool for identical statements was increasing-- for each non-reusable statement generated.--

-- A flush of the shared pool was the only solution to solve this performance-- problem, resulting that all other query returned again in less than a second.---- It was determined that an automatic procedure was needed to monitor-- the shared pool and flush it when it reached 60-70% of capacity.

---- The following procedue was created:--

CREATE OR REPLACE VIEW sys.sql_summaryAS SELECT username,

sharable_mem, persistent_mem, runtime_mem FROM sys.v_$sqlarea a, dba_users b WHERE a.parsing_user_id = b.user_id;

CREATE OR REPLACE PROCEDURE flush_itAS CURSOR get_share IS SELECT SUM (sharable_mem) FROM sys.sql_summary;

CURSOR get_var

IS SELECT VALUE FROM v$sga WHERE name LIKE 'Var%';

CURSOR get_time IS SELECT SYSDATE FROM DUAL;

todays_date DATE;

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mem_ratio NUMBER; share_mem NUMBER; variable_mem NUMBER; cur INTEGER; sql_com VARCHAR2 (60); row_proc NUMBER;BEGIN OPEN get_share;

OPEN get_var;

FETCH get_share INTO share_mem;

DBMS_OUTPUT.PUT_LINE ('share_mem: ' || TO_CHAR (share_mem));

FETCH get_var INTO variable_mem;

DBMS_OUTPUT.PUT_LINE ('variable_mem: ' || TO_CHAR (variable_mem));

mem_ratio := share_mem / variable_mem; DBMS_OUTPUT.PUT_LINE ('mem_ratio: ' || TO_CHAR (mem_ratio));

IF (mem_ratio > 0.3) THEN

DBMS_OUTPUT.PUT_LINE ('Flushing Shared Pool ...'); cur := DBMS_SQL.open_cursor; sql_com := 'ALTER SYSTEM FLUSH SHARED_POOL'; DBMS_SQL.PARSE (cur, sql_com, DBMS_SQL.v7); row_proc := DBMS_SQL.EXECUTE (cur); DBMS_SQL.CLOSE_CURSOR (cur); END IF;END;/

-- This procedure was then loaded into the job queue and scheduled to run-- every hour using the following commands:

DECLARE job NUMBER;BEGIN DBMS_JOB.SUBMIT (job, 'flush_it;', SYSDATE, 'sysdate+1/24');END;/