SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
C-84
CONTROL TABLE Directive
For an example, see information about local autonomy under Considerations—
CONTROL TABLE on page C-85.
SYNCDEPTH { 0 | 1 }
controls the method of writing to the disk process for nonaudited tables and views:
The default SYNCDEPTH for a table or protection view is 1.
(For audited tables, or views with audited underlying tables, SYNCDEPTH is
always 1; directives to change it are ignored.)
TABLELOCK { OFF | ON | ENABLE }
specifies whether to use table locks for subsequently compiled DML statements
that access the table or view:
ENABLE SQL decides whether to use table locks.
TABLELOCK ENABLE is the default.
If you want to increase access performance and are not concerned with
concurrency, use TABLELOCK ON.
If TABLELOCK OFF is in effect and SQLCI or a host language program attempts to
acquire more row locks than allowed, the file system issues error 35 (Lock limit has
been reached).
Note that for nonaudited tables, locking protocol enforced by DP2 is not available.
Therefore, if sequential block buffering (either RSBB or VSBB) is used to access a
nonaudited table, SQL always acquires a table lock, regardless of the setting of the
TABLELOCK option and access option.
TIMEOUT { value | DEFAULT } [ SECOND[S] ]
specifies the number of seconds allowed to complete file-system requests in DML
operations.
0 prevents the disk process from sending checkpoint messages. Might
slightly improve performance but makes modifications less reliable
because an error during an update that modifies several rows halts
processing of the statement.
1 enables retry of a message to the disk process, if necessary. Each time
data is written to a disk process, the primary disk process sends a
checkpoint message to the backup disk process with a description of the
operation. This is the preferred option for nonaudited tables, although it
is not as safe as auditing.
OFF never use table locks
ON always use table locks