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Frequently asked questions on comdb2

Setting the Log Location

The default comdb2 root directory is configured at build-time, but can be overridden at runtime via the $COMDB2_ROOT environmental variable. In the absence of an override, the default logfile directory will be:


The logfile directory can be overridden in a database's lrl file via the location logs /path/to/logs/ directive.

A simple example: consider a database named customerdb. If the $COMDB2_ROOT environmental variable is set to /opt/comdb2, then the database will create the following three logfiles upon starting:


If a user wishes to change the location of these logfiles to /var/logs/comdb2, they should add the following directive to the customerdb database's lrl file:

location logs /var/logs/comdb2

This will create the following three logfiles:


[//]: <> ## stdout/stderr [//]: <> TODO - i don't know if we are going to redirect to stdout / stderr [//]: <> after opensource.

Long Requests

Long requests are collected under comdb2's request-logging subsystem and reported in the database's <dbname>.longreqs file. SQL statements which take longer than the threshold to complete are reported in the long-requests file. The long-requests file additionally reports other information which may have impacted the request. The default long-request reporting threshold is 5000 milliseconds. This value can be changed dynamically at runtime via the cdb2api, or the cdb2sql command line utility:

cdb2sql customerdb local "exec procedure sys.cmd.send('reql longsqlrequest 0')"

Will set the long-request threshold to 0 milliseconds, which will have the effect of logging all of the incoming sql requests.

Status Log

Comdb2 records global request status information for a database in its <dbname>.statreqs file. Unlike the long requests file, which reports its information per-request, the statreqs file is updated every minute with global information (i.e., the number of new requests, the number of additional log bytes, IO information, etc).