NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
C-85
Considerations—CONTROL TABLE
To disable VSBB for INSERT operations, use this directive:
CONTROL TABLE * SEQUENTIAL INSERT OFF
•
Buffered INSERT or UPDATE operations on nonaudited tables
SQL buffers INSERT or UPDATE operations on nonaudited tables only if the
SEQUENTIAL option is ON and SYNCDEPTH is 0. (You can specify both these
options with CONTROL TABLE.) For INSERT operations, you must also set the
TABLELOCK option to ON (again, with CONTROL TABLE), or use a LOCK
TABLE statement that specifies IN EXCLUSIVE MODE. For an INSERT
operation, specify FOR REPEATABLE ACCESS also.
To ensure data integrity you must use the FREE RESOURCES statement to flush
buffers for nonaudited tables before you exit SQLCI or the host program. For host
programs, any flush errors are returned to the SQLCA.
•
Conditions that flush or invalidate the buffer
The conditions listed in the following table trigger flushing the INSERT/UPDATE
buffer or invalidating the READ buffers. If a problem such as a path error or disk
full error occurs during the flush, the disk process returns the error.
Condition
Flushes Buffer
for INSERTs
and UPDATEs
Invalidates
Buffer for
READs
A DML operation occurs
on a table, interrupting a
sequential operation that
has already begun.
XX
The buffer is full. X N.A.
A cursor is opened or
closed on a table or view
with a sequential operation
running.
XN.A.
A TMF transaction
completes on an audited
table.
XX
A server replies to a
requester.
XX
A FREE RESOURCES
statement is executed by
the current process.
XX
The table is closed. X X
The current TMF
transaction is not the same
as the TMF transaction
corresponding to the active
INSERT or UPDATE
operations.
XX