Asynchronous log service (ALS) increases scalability in Adaptive Server and provides higher throughput in logging subsystems for high-end symmetric multiprocessor systems.
You cannot use ALS if you have fewer than four engines; if you attempt to do so, with fewer than 4 online engines an error message appears.
You can enable, disable, or configure ALS using the sp_dboption stored procedure:
sp_dboption <db Name>, "async log service", "true|false"
After issuing sp_dboption, you must issue a checkpoint in the database for which you are setting the ALS option:
sp_dboption "mydb", "async log service", "true" use mydb
checkpoint
You can use the checkpoint to identify the one or more databases or use an all clause:
checkpoint [all | [dbname[, dbname[, dbname.....]]]
To disable ALS, enter:
sp_dboption "mydb", "async log service", "false" use mydb
checkpoint -------------
Before you disable ALS, make sure there are no active users in the database. If there are active users in the database when you disable ALS, you see this error message:
Error 3647: Cannot put database in single-user mode. Wait until all users have logged out of the database and issue a CHECKPOINT to disable "async log service".
Use sp_helpdb to see whether ALS is enabled in a specified database:
sp_helpdb "mydb" ---------- mydb 3.0 MB sa 2 July 09, 2002 select into/bulkcopy/pllsort, trunc log on chkpt,
async log service
For more information on these stored procedures, see the Adaptive Server Reference Manual: Procedures.
