Filter
Top Products
2-52 IBM Informix OnLine Database Server Administrator’s Guide
Shared-Memory Internal Tables
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 thelocks 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.
OnLine Page-Cleaner Table
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.
OnLine Tblspace Table
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.