DBUPSPACE

The DBUPSPACE environment variable lets you specify and constrain the amount of system disk space that the UPDATE STATISTICS statement can use when trying to simultaneously construct multiple column distributions.

>>-setenv--DBUPSPACE-- max-- :-- default-----------------------><
 

max

is a positive integer, specifying the maximum disk space (in kilobytes) to allocate for sorting in UPDATE STATISTICS operations.

default

is a positive integer, specifying the maximum amount of memory (in kilobytes) to allocate.

For example, to set DBUPSPACE to 2,500 kilobytes of disk space and 1,000 kilobytes of memory, enter this command:

setenv DBUPSPACE 2500:1 

After you set this value, the database server can use no more than 2,500 kilobytes of disk space during the execution of an UPDATE STATISTICS statement. If a table requires 5 megabytes of disk space for sorting, then UPDATE STATISTICS accomplishes the task in two passes; the distributions for one half of the columns are constructed with each pass.

If you do not set DBUPSPACE, the default is a megabyte (1,024 kilobytes) for max, and the maximum amount of memory that is available without using PDQ for default. If you attempt to set DBUPSPACE to any value less than 1,024 kilobytes, it is automatically set to 1,024 kilobytes, but no error message is returned. If this value is not large enough to allow more than one distribution to be constructed at a time, at least one distribution is done, even if the amount of disk space required to do this is more than what DBUPSPACE specifies.