This command executes a query in a certain language. This might be, for example Procedural Query Language (PQL) or Continuous Query Language (CQL). There are three different commands to execute such a query: #QUERY, #ADDQUERY and #RUNQUERY. While #QUERY and #ADDQUERY (they are one and the same) only passes the definied query to Odysseus, the #RUNQUERY additionally starts the query. This means, a query that was added with #QUERY or #ADDQUERY is inactive and not started until it is explicetely started. The #RUNQUERY in contrast immediatly starts a query after it is added, e.g. by using #STARTQUERIES .
The query command is dependent on the current parser (which is set by #PARSER) and the current transformation configuration (which is set by #TRANSCFG). Therefore, it is necessary to run these two commands before. Furthermore, you can switch to other parsers / transformation within one script by using #PARSER or #TRANSCFG again. Thus, if you want to run a query in CQL that last #PARSER command before should set the parser to "CQL".
If #QName is defined before, the query will get this name.
The example shows four queries after the parser is set to CQL and the transformation configuration is set to Standard. The first one uses #QUERY and it is executed as a CQL-Query, but not started. The second query is equal to the first one (it still uses CQL and is not started). The third query also uses CQL and the Standard transformation configuration, but is (in contrast to the first and second) started (it is directly running). Then, the parser is switched to PQL, so that the fourth query is parsed by the PQL-Parser and not by the CQL-Parser anymore.
This command installs a query and starts it immediately. See #QUERY for parameters, examples and details.
Query can be modified via Odysseus script. For this, the queries must be named. A query can be named with #QNAME:
This command can be used to start a named query.
This command can be used to stop a nazmed query.
This comand can be used to pause a query. Remark: received elements are stored, so this can lead to a memory problem.
This comand can be used to reduce load of a query by throwing away some received elements. The factor is a number between 0 and 100 where 0 means keep every element and 100 throw away every element
A suspended query can be resumed by this.
Remove a query from the system. Cannot be undone.
With this comand, the execution of a Odysseus Script can be paused until a query is stopped or removed. period in ms states in which time intervals the query should be checked (default is 1000). maxwaitingtime states how should be waited for the query at maxium (default wait forever).
This command starts all installed queries that are not running at the moment.
This command is used to control how buffers are (automatically) placed within the query plan if a query is transformed (e.g. by #QUERY).
Adds a buffer before each operator:
Adds a buffer after each source:
Adds a buffer for each query:
This command switches the query sharing (which tries to optimize a query be reusing parts of already installed query plans) on or off.
This command switches the rewriting (tries to optimize a query plan by switching, deleting, splitting or merging operators without changing the query's semantics) on or off.
In the default processing scenario, all elements in Odysseus are tagged with time stamp meta data. This command can be used to define the meta data.
Hint: This flag overwrites the standard configuration so you must provide all metadata that should be used!
Remark: There are some combined metadata elements available: e.g. IntervalLatency or IntervalLatencyPriority
Enable predicate optimization for the current query. The optimizer tries to simplify the predicates used in select operations and transforms the predicate into its conjunctive normal form to move clauses in the expression down to the sources.
The parser: Which parsers are available strongly depends on the current system setting and installed features. Normally in the default product, there is "PQL" for Procedural Query Language (PQL) and "CQL" for Continuous Query Language (CQL).
Set the name of the following query.
Some special processing could require query specific processing.This command can be used to set these parameters as key value pairs.
Set the priority of the next following query