Multistage Queries
In non-mirror mode, the DAH supports multistage querying. You can configure the stage information for multistage querying in the DAH configuration file. A multistage query is processed in stages across specified VDBs. The specified VDBs serve the query in stages, until they find the required number of results.
You enable multistage querying by using the MultiStage
or MultiStageMinResults
action parameters with Query
or SuggestOnText
actions. For details of multistage action parameters, refer to the IDOL Server Reference.
-
Open the DAH configuration file in a text editor.
-
Find the
[MultiStageQuery]
section. -
Add the
Stages
option to specify the total number of stages to use for a multistage query. For example:[MultiStageQuery] Stages=3
-
For each stage, use the
N
option to specify a comma-separated list of VDBs to use for that stage, starting with stage0
(zero). The DAH processes the query stage by stage, in order. For example:[MultiStageQuery] Stages=3 0=db0 1=db1 2=db2,db3
-
Save and close the configuration file.
-
Restart the DAH for your changes to take effect.
NOTE: If you specify the total number of stages and VDBs to use at each stage by using parameters in the Query
or SuggestOnText
action, these settings override the DAH configuration settings for multistage querying.