6. QUEL and EQUEL Statements : Copy Statement—Copy Data : WITH Clause for COPY : Fillfactor, Minpages, and Maxpages Options
 
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Fillfactor, Minpages, and Maxpages Options
Fillfactor specifies the percentage (from 1 to 100) of each primary data page that must be filled with rows, under ideal conditions. For example, if you specify a fillfactor of 40, the DBMS Server fills 40% of each of the primary data pages in the restructured table with rows. You can specify this option with the isam, hash, or btree structures. Take care when specifying large fillfactors because a nonuniform distribution of key values can later result in overflow pages and thus degrade access performance for the table.
Minpages specifies the minimum number of primary pages a hash table must have. Maxpages specifies the maximum number of primary pages a hash table can have. Minpages and maxpages must be at least 1. If both minpages and maxpages are specified in a modify statement, minpages must not exceed maxpages.
For best performance, the values that you choose for minpages and maxpages must be a power of 2. If you choose a number other than a power of 2, the DBMS Server can change the number to the nearest power of 2 when the modify executes. If you want to ensure that the number you specify is not changed, set both minpages and maxpages to that number.
Default values for fillfactor, minpages and maxpages are listed in the following table:
Storage Structure
Fillfactor
Minpages
Maxpages
hash
50
16
no limit
compressed hash
75
1
no limit
isam
80
n/a
n/a
compressed isam
100
n/a
n/a
btree
80
n/a
n/a
compressed btree
100
n/a
n/a