The following query parameters are use by Solr for all requests...
Parameters That Affect Processing
If a request uses the /select URL, and no SolrRequestHandler has been configured with /select as its name, then Solr uses the qt parameter to determine which Query Handler should be used to process the request. Valid values are any of the names specified by <requestHandler ... /> declarations in solrconfig.xml
"qt" doesn't really have a default, but the default request handler to dispatch to is "/select".
The wt (writer type) parameter is used by Solr to determine which QueryResponseWriter should be used to process the request. Valid values are any of the names specified by <queryResponseWriter... /> declarations in solrconfig.xml
The default value is "standard" (xml).
The NOW parameter is used internally by Solr to set a fixed time for evaluating Date based expresions -- notably for usages of DateField and "Date Math" parsing (ie: date range queries and range faceting). It's primary usage is in intra-node requests during distributed search, to ensure a uniform value is used across all nodes regardless of any slight inconsistencies/delays between when requests are recieved for each shard; but it may also be explicitly specified by clients to override the default behavior.
The value of the TZ param is expressed in milliseconds since epoch.
The TZ parameter can be specified to override the default TimeZone (UTC) used for the purposes of adding and rounding in date math. The local rules for the specified TimeZone (including the start/end of DST if any) determine when each arbitrary day starts -- which affects not only rounding/adding of DAYs, but also cascades to rounding of HOUR, MIN, MONTH, YEAR as well.
For example "2013-03-10T12:34:56Z/YEAR" using the default TZ would be 2013-01-01T00:00:00Z but with TZ=America/Los_Angeles, the result is 2013-01-01T08:00:00Z. Likewise, 2013-03-10T08:00:00Z+1DAY evaluates to 2013-03-11T08:00:00Z by default, but with TZ=America/Los_Angeles the local DST rules result in 2013-03-11T07:00:00Z
The value of the TZ param can be any zone ID supported by The java TimeZone class.
Parameters That Produce Debugging Info
If the echoHandler parameter is true, Solr places the name of the handle used in the response to the client for debugging purposes.
The echoParams parameter tells Solr what kinds of Request parameters should be included in the response for debugging purposes, legal values include:
- none - don't include any request parameters for debugging
- explicit - include the parameters explicitly specified by the client in the request
- all - include all parameters involved in this request, either specified explicitly by the client, or implicit because of the request handler configuration.