1、以前开过optimizer_capture_sql_plan_baseline=true？

2、参数解释

OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES=false

For any repeatable SQL statement that does not already exist in the plan history, the database does not automatically create an initial SQL plan baseline for the statement.

我理解optimizer_capture_sql_plan_baseline=false，只是控制以前没有baseline的sql不再生成baseline，以前有baseline的sql会根据统计信息变化等原因，继续生成新的baseline

3、可以删除某条SQL的现有baseline，以后一不会生成新的了

DECLARE
v_dropped_plans number;
BEGIN
v_dropped_plans := DBMS_SPM.DROP_SQL_PLAN_BASELINE (
sql_handle => 'SQL_1f842bf5e900a2f2'
);
DBMS_OUTPUT.PUT_LINE('dropped ' || v_dropped_plans || ' plans');
END;
/
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