NET/MASTER Network Control Language (NCL) Programmer's Guide

Controlling Access to UDBs by NonStop NET/MASTER MS
Working With Files
12–14 106160 Tandem Computers Incorporated
Performing a RESET Operation on a Single UDB. To perform a RESET operation on a single
UDB before you open it, use the UDBCTL RESET command. The following example
performs a RESET operation on MYFILE:
UDBCTL RESET=$DATA.SUBVOL.MYFILE
To perform a RESET operation on a single UDB when you open it, use the RESET
operand of the UDBCTL OPEN command. The following example performs a RESET
operation on MYFILE:
UDBCTL OPEN=$DATA.SUBVOL.MYFILE ID=UDBID1 RESET
Performing a RESET Operation on the First File in a UDB Pair. To perform a RESET operation
on the first file in a UDB pair, use the RESET operand of the UDBCTL OPEN
command. The following example performs a RESET operation on MYFILE1 in the
UDB pair:
UDBCTL OPEN=($DATA.SUBVOL.MYFILE1,$DATA.SUBVOL.MYFILE2) RESET
The second file in the UDB pair is not affected.
Buffer Management Options
The Enscribe access method includes two buffer management options for handling
UDBs: cache buffering and sequential block buffering. When you open a UDB or
UDB pair with UDBCTL OPEN, you can specify the buffer management options that
you want the Enscribe access method to use on the UDB or UDB pair with three
operands: BUFFERED, ACCESS, and SEQUENTIALBUFFERING.
These operands affect the performance of the Enscribe access method as it processes a
UDB; they do not affect how NCL processes a UDB. Accordingly, this section does not
describe how to use the operands, but simply provides some examples.
The following example opens the UDB MYFILE, assigns it the identifier of UDBID1,
performs a PURGEDATA operation, and specifies that records are to be buffered in
cache memory before being transferred to the disk:
UDBCTL OPEN=$DATA.SUBVOL.MYFILE ID=UDBID1 RESET BUFFERED
The following example opens the UDB MYFILE, assigns it the identifier of UDBID1,
and specifies shared sequential buffering:
UDBCTL OPEN=$DATA.SUBVOL.MYFILE ID=UDBID1 BUFFERED
ACCESS=SEQUENTIAL
The following example opens the UDB MYFILE, assigns it the identifier of UDBID1,
and specifies shared access to the disk cache:
UDBCTL OPEN=$DATA.SUBVOL.MYFILE ID=UDBID1
SEQUENTIALBUFFERING=SHARED
Refer to the Enscribe Programmer's Guide for additional information on buffering
strategies.