|
71) 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.
72) What is dynamic SQL? –
Dynamic SQL is a SQL statement created at program execution time.
73) When is the access path determined for dynamic SQL? –
At run time, when the PREPARE statement is issued.
74) Suppose I have a program which uses a dynamic SQL and it has been
performing well till now. Off late, I find that the performance has
deteriorated. What happened? –
Probably RUN STATS is not done and the program is using a wrong index due to
incorrect stats.
Probably RUNSTATS is done and optimizer has chosen a wrong access path based
on the latest statistics.
75) How does DB2 store NULL physically?
as an extra-byte prefix to the column value. physically, the nul prefix is
Hex ’00’ if the value is present and Hex ‘FF’ if it is not.
|
