What is EXPLAIN?

DB2 ( IBM Database 2 ) Interview Questions

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What is EXPLAIN?

EXPLAIN is used to display the access path as determined by the optimizer for a SQL statement. It can be used in SPUFI (for single SQL statement ) or in BIND step ( for embedded SQL). The results of EPLAIN is stored in U.PLAN_TABLE where U is the authorization id of the user.

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Other Interview Questions

• How does the processing of a correlated subquery differ from a non correlated subquery ?
• How does DB2 store NULL physically?
• What is the cascade rule and how does it relate to deletions made with a subselect ?
• What is FREEPAGE and PCTFREE in TABLESPACE createion?
• How do you do the EXPLAIN of a dynamic SQL statement ?
• What is Declaration Generator ( DCLGEN )?
• When is the access path determined for dynamic SQL?
• What are the levels of isolation available with DB2V4?
• Can we declare DB2 HOST variable in COBOL COPY book ?
• What is cursor stability?
• More...