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Query Context
The query context is used for various query configuration parameters. The following parameters apply to all queries.
| property | default | description |
|---|---|---|
| timeout | 0 (no timeout) |
Query timeout in milliseconds, beyond which unfinished queries will be cancelled. |
| priority | 0 |
Query Priority. Queries with higher priority get precedence for computational resources. |
| queryId | auto-generated | Unique identifier given to this query. If a query ID is set or known, this can be used to cancel the query |
| useCache | true |
Flag indicating whether to leverage the query cache for this query. This may be overridden in the broker or historical node configuration |
| populateCache | true |
Flag indicating whether to save the results of the query to the query cache. Primarily used for debugging. This may be overriden in the broker or historical node configuration |
| bySegment | false |
Return "by segment" results. Primarily used for debugging, setting it to true returns results associated with the data segment they came from |
| finalize | true |
Flag indicating whether to "finalize" aggregation results. Primarily used for debugging. For instance, the hyperUnique aggregator will return the full HyperLogLog sketch instead of the estimated cardinality when this flag is set to false |
| chunkPeriod | P0D (off) |
At the broker node level, long interval queries (of any type) may be broken into shorter interval queries to parallelize merging more than normal. Broken up queries will use a larger share of cluster resources, but may be able to complete faster as a result. Use ISO 8601 periods. For example, if this property is set to P1M (one month), then a query covering a year would be broken into 12 smaller queries. The broker uses its query processing executor service to initiate processing for query chunks, so make sure "druid.processing.numThreads" is configured appropriately on the broker. groupBy queries do not support chunkPeriod by default, although they do if using the legacy "v1" engine. |
In addition, some query types offer context parameters specific to that query type.
TopN queries
| property | default | description |
|---|---|---|
| minTopNThreshold | 1000 |
The top minTopNThreshold local results from each segment are returned for merging to determine the global topN. |
Timeseries queries
| property | default | description |
|---|---|---|
| skipEmptyBuckets | false |
Disable timeseries zero-filling behavior, so only buckets with results will be returned. |