List of DB2 Interview Questions & Answers

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What are leaf pages? [ 29 ]

They are the opposite of root pages. Leaf pages are the lowest level index pages - the pages that contain index entries and information to the corresponding table rows.

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.What is an asychronous write? [ 18 ]

It is a write to disk that may occur before or long after a commit. The write is controlled by the buffer manager.

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What is the difference between IN subselects and EXISTS subselect? [ 13 ]

If there is an index on the attributes tested an IN is more efficient since DB2 uses the index for the IN. (IN for index is the mnemonic)

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Compare a subselect to a join. [ 25 ]

Any subselect can be rewritten as a join, but not vice versa. Joins are usually more efficient as join rows can be returned immediately, subselects require a temporary work area for inner selects results while processing the outer select.

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DB2 can implement a join in three ways using a merge join, a nested join or a hybrid join. Explain the differences. [ 13 ]

"Answer not available"

What is the purpose of the WHENEVER statement? [ 17 ]

The WHENEVER statement is coded once in the host program to control program actions depending on the SQL-CODE returned by each sql statement within the program.

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.What is the significance of the CURSOR WITH HOLD clause in a cursor declaration? [ 11 ]

The clause avoids closing the cursor and repositioning it to the last row processed when the cursor is reopened.

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What is cursor stability? [ 18 ]

Cursor stability means that DB2 takes a lock on the page the cursor is accessing and releases the lock when the cursor moves to another page.

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What is the difference between static and dynamic sql? [ 15 ]

Static sql is hard-coded in a program when the programmer knows the statements to be executed. For dynamic sql the program must dynamically allocate memory to receive the query results.

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What is an intent lock? [ 14 ]

An intent lock is at the table level for a segmented tablespace or at the tablespace level for a nonsegmented tablespace. They indicate at the table or tablespace level the kinds of locks at lower levels.

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