IBM 000-8697 Manual Do Utilizador

IBM Informix OnLine Database Server Administrator’s Guide

A byte lock is only generated if you are using

VARCHAR

data types. The byte

lock exists solely for rollforward and rollback execution, so you must be
working in a database that uses logging. Byte locks only appear in tbstat -k
output if you are using row-level locking; otherwise, they are merged with
the page lock.

The upper limit for the maximum number of locks (specified as

LOCKS

in the

configuration file) is 256,000. The lower boundary for

LOCKS

 is the number

of user processes (the current value of

USERS

) multiplied by 20.

The number of entries in the lock hash table is based on the number of entries
in the locks table (specified as

LOCKS

in the configuration file). The maximum

number of hash values is the largest power of 2 that is less than the value
specified by the expression (

LOCKS

 divided by 16). Each entry in the lock

hash table occupies 12 bytes.

The page-cleaner table tracks the state and location of each of the page-
cleaner daemons, tbpgcl, that was specified during configuration.

The page-cleaner table always contains 32 entries, regardless of the number
of page cleaners specified by

CLEANERS

 in your configuration file.

Each entry in the page-cleaner table occupies 20 bytes.

The upper limit for the maximum number of page cleaners (specified as

CLEANERS

in the configuration file) is 32. The lower boundary for

CLEANERS

is 0.

When

CLEANERS

 is set to 0, the tbinit daemon assumes responsibility for

page cleaning. When

CLEANERS

is set to any value greater than 0, that is the

number of tbpgcl daemon processes managed by tbinit.

The tblspace table tracks all active tblspaces in the OnLine system. An active
tblspace is currently open to any OnLine user process. The count of active
tblspaces includes database tables, temporary tables, and internal control
tables, such as system catalog tables. Each active table receives one entry in
the active tblspace table. Entries in the tblspace table are tracked in an
associated hash table.