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A question about huge difference in cardinality of a query with 3 predicates

edited Oct 23, 2017 6:37AM in SQL Performance (MOSC) 4 commentsAnswered

Hi All,

I am having an issue of a query getting a bad plan  -which I have narrowed down to major mismatch between estimated and actual cardinality of one of the tables involved in the query. I need 

help from experts on understanding why the cardinality estimate is wrong and what can be done to rectify.  For this purpose I have created a test table with required columns and tried to

create same situation (of cardinality mismatch) and following are the details on it. (Oracle version is : 11.2.0.4 on Linux.)

Table structure: CREATE TABLE processes

(

process_id    NUMBER (12) NOT NULL PRIMARY KEY,

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