What is IMAGECOPY ?
It is full backup of a DB2 table which can be used in recovery. Read more »
Archive for March, 2008
What is REORG? When is it used?
REORG reorganizes data on physical storage to reclutser rows, positioning overflowed rows in their proper sequence, to reclaim space, to restore free space. It... Read more »
Give some example of statistics collected during RUNSTATS ?
Number of rows in the table, Percent of rows in clustering sequence, Number of distinct values of indexed column, Number of rows moved to a nearby/fairway page... Read more »
When will you chose to run RUNSTATS ?
After a load, or after mass updates, inserts, deletes, or after REORG. Read more »
What is RUNSTATS ?
A DB2 utility used to collect statistics about the data values in tables which can be used by the optimizer to decide the access path. It also collects statistics... Read more »
How do you insert a record with a nullable column ?
To insert a NULL, move -1 to the null indicator, To insert a valid value, move 0 to the null indicator Read more »
What does it mean if the null indicator has -1, 0, -2 ?
-1 : the field is null; 0 : the field is not null; -2 : the field value is truncated Read more »
How do you retrieve the data from a nullable column ?
Use null indicators. Syntax … INTO :HOSTVAR:NULLIND Read more »
How does DB2 store NULL physically ?
As an extra-byte prefix to the column value. Physically, the null prefix is Hex ‘00′ if the value is present and Hex ‘FF’ if it is not. Read more »
When is the access path determined for dynamic SQL ?
At run time, when the PREPARE statement is issued. Read more »
What is dynamic SQL ?
Dynamic SQL is a SQL statement created at program execution time. Read more »
Lot of updates have been done on a table due to which indexes have gone haywire. What do you do ?
Looks like index page split has occurred. DO a REORG of the indexes. Read more »
How would you print the output of an SQL statement from SPUFI ?
Print the output dataset. Read more »
In SPUFI suppose you want to select maximum of 1000 rows, but the select returns only 200 rows. What are the 2 SQLCODEs that are returned ?
+100 (for successful completion of the query), 0 (for successful COMMIT if AUTOCOMMIT is set to Yes). Read more »