Also referred to as the
ACC block, this is
the access control and lock management module. It is also
responsible for storing primary key and unique key hash indexes
are stored. This block is found in
contains the following files:
Dbacc.hpp: Defines the
Dbaccclass, along with structures for operation, scan, table, and other records.
Dbaccclass constructor and destructor; methods for initialising data and records.
ACC block handles database index
structures, which are stored in 8K pages. Database locks are
also handled in the
When a new tuple is inserted, the
stores the tuple in a suitable space and returns an index (a
reference to the address of the tuple in memory).
ACC stores both the primary key and this
tuple index of the tuple in a hash table.
TUP block, the
ACC block implements part of the checkpoint
protocol. It also performs undo logging. It is implemented by
Dbacc class, which is defined in
See also Section 8.4.10, “The DBTUP Block”.