Improving the responsiveness of Lifecycle Query Engine queries

When the query activity is high, the load on the server can affect the responsiveness of the queries. As an administrator, you can take several measures to improve the resiliency of Lifecycle Query Engine and the responsiveness of queries. For example, you can define limits for running queries, enable query caching, or enable load shedding.

Query configuration

The Lifecycle Query Engine query service runs queries on the indexed data. You can define the properties for the service that apply to all queries that are run against index. By default, the query service is enabled, and the values are applied to all the nodes.

One way that you can manage query performance is to define limits for queries by specifying the following properties:

Screen capture of the Query properties on the Query Service page.

If LQE is performing intensive work, such as creating an index for a new data source or backing up the data, you might improve performance by temporarily disabling the query service.

Query caching

When you enable query caching, query results are cached in the central database and are shared across all users who belong to the same access groups. Information about the groups that the query touches and the subset of those groups that the user belongs to is stored in the cache with the query results.

LQE provides two types of caching: HTTP Response and Query result. HTTP query caching is complementary to query result caching. When a system is under load, both caching operations can help reduce the load. You can select the type of caching to use and specify how long query results are cached.
Note: If your users want access to the most recent data in the LQE index, do not enable either type of caching.
Screen capture of the Query Caching properties on the Query Service page.
  • HTTP Response Caching Enabled: Query results are cached on the client.
  • HTTP Response Max Age (seconds): The amount of time in seconds that cached query results are available on the client. The default is 120.
  • Query Result Caching Enabled: Query results are cached on the server.
  • Query Result Cache Expiration (seconds): The amount of time in seconds that cached query results are available on the server. The default is 120.

How it works: Two users, User 1 and User 2, are in the same resource group. User 1 runs Query A. If User 2 runs Query A within 120 seconds, he will get cached query results. If User 2 runs Query A after 120 seconds, the query runs again and he gets updated results. If you enable query load shedding, this behavior changes when the warning and critical thresholds are reached. See Query load shedding.

Query load shedding

By defining query load shedding threshold values, you can control how Lifecycle Query Engine behaves when the query load is heavy and the thresholds are reached.

Screen capture of the Load Shedding properties on the Query Service page.

When load shedding is disabled, query results are cached and expire based on the Query result cache expiration value. However, when load shedding is enabled, LQE has three operating conditions:
  • Normal: The query runs and the results are cached for 120 seconds (or the Query result cache expiration value.) If a user with exact permissions runs the same query within 120 seconds, the cached results are returned, otherwise the query is run and the results are cached for 120 seconds. Normal operating conditions apply whether load shedding is enabled or disabled.
  • Warning: If the queries historically run in less time than the Max time of a fast query value, the query runs and the results are cached. Otherwise, cached results are returned - even if they have expired.
  • Critical: When the critical threshold values are reached, no new queries are run and you see only the cached results.
Note: The threshold values that you define on the Query Service page apply to all nodes. You can specify threshold values for individual nodes on the LQE Nodes page. See Managing Lifecycle Query Engine nodes.
Tip: You can monitor the performance of Lifecycle Query Engine on the Home page, or on the Statistics page. You can also configure LQE to notify you when the thresholds are exceeded.

Feedback