io.druid.query.select

Class SelectQueryQueryToolChest

java.lang.Object

io.druid.query.QueryToolChest<Result<SelectResultValue>,SelectQuery>

io.druid.query.select.SelectQueryQueryToolChest

public class SelectQueryQueryToolChest
extends QueryToolChest<Result<SelectResultValue>,SelectQuery>

Constructor Summary

Constructors

Constructor and Description
SelectQueryQueryToolChest(com.fasterxml.jackson.databind.ObjectMapper jsonMapper, IntervalChunkingQueryRunnerDecorator intervalChunkingQueryRunnerDecorator, com.google.common.base.Supplier<SelectQueryConfig> configSupplier)

Method Summary

Modifier and Type	Method and Description
<T extends LogicalSegment> List<T>	filterSegments(SelectQuery query, List<T> segments) This method is called to allow the query to prune segments that it does not believe need to actually be queried.
CacheStrategy<Result<SelectResultValue>,Object,SelectQuery>	getCacheStrategy(SelectQuery query) Returns a CacheStrategy to be used to load data into the cache and remove it from the cache.
com.fasterxml.jackson.core.type.TypeReference<Result<SelectResultValue>>	getResultTypeReference() Returns a TypeReference object that is just passed through to Jackson in order to deserialize the results of this type of query.
com.metamx.emitter.service.ServiceMetricEvent.Builder	makeMetricBuilder(SelectQuery query) Creates a builder that is used to generate a metric for this specific query type.
com.google.common.base.Function<Result<SelectResultValue>,Result<SelectResultValue>>	makePreComputeManipulatorFn(SelectQuery query, MetricManipulationFn fn) Creates a Function that can take in a ResultType and return a new ResultType having applied the MetricManipulatorFn to each of the metrics.
QueryRunner<Result<SelectResultValue>>	mergeResults(QueryRunner<Result<SelectResultValue>> queryRunner) This method wraps a QueryRunner.
QueryRunner<Result<SelectResultValue>>	preMergeQueryDecoration(QueryRunner<Result<SelectResultValue>> runner) Wraps a QueryRunner.

Methods inherited from class io.druid.query.QueryToolChest

makePostComputeManipulatorFn, postMergeQueryDecoration

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SelectQueryQueryToolChest

@Inject
public SelectQueryQueryToolChest(com.fasterxml.jackson.databind.ObjectMapper jsonMapper,
                                         IntervalChunkingQueryRunnerDecorator intervalChunkingQueryRunnerDecorator,
                                         com.google.common.base.Supplier<SelectQueryConfig> configSupplier)

Method Detail

mergeResults

public QueryRunner<Result<SelectResultValue>> mergeResults(QueryRunner<Result<SelectResultValue>> queryRunner)

Description copied from class: QueryToolChest

This method wraps a QueryRunner. The input QueryRunner, by contract, will provide a series of ResultType objects in time order (ascending or descending). This method should return a new QueryRunner that potentially merges the stream of ordered ResultType objects.

Specified by:

mergeResults in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Parameters:

queryRunner - A QueryRunner that provides a series of ResultType objects in time order (ascending or descending)

Returns:

a QueryRunner that potentially merges the stream of ordered ResultType objects

makeMetricBuilder

public com.metamx.emitter.service.ServiceMetricEvent.Builder makeMetricBuilder(SelectQuery query)

Description copied from class: QueryToolChest

Creates a builder that is used to generate a metric for this specific query type. This exists to allow for query-specific dimensions on metrics. That is, the ToolChest is expected to set some meaningful dimensions for metrics given this query type. Examples might be the topN threshold for a TopN query or the number of dimensions included for a groupBy query.

Specified by:

makeMetricBuilder in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Parameters:

query - The query that is being processed

Returns:

A MetricEvent.Builder that can be used to make metrics for the provided query

makePreComputeManipulatorFn

public com.google.common.base.Function<Result<SelectResultValue>,Result<SelectResultValue>> makePreComputeManipulatorFn(SelectQuery query,
                                                                                                                        MetricManipulationFn fn)

Description copied from class: QueryToolChest

Creates a Function that can take in a ResultType and return a new ResultType having applied the MetricManipulatorFn to each of the metrics.

This exists because the QueryToolChest is the only thing that understands the internal serialization format of ResultType, so it's primary responsibility is to "decompose" that structure and apply the given function to all metrics.

This function is called very early in the processing pipeline on the Broker.

Specified by:

makePreComputeManipulatorFn in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Parameters:

query - The Query that is currently being processed

fn - The function that should be applied to all metrics in the results

Returns:

A function that will apply the provided fn to all metrics in the input ResultType object

getResultTypeReference

public com.fasterxml.jackson.core.type.TypeReference<Result<SelectResultValue>> getResultTypeReference()

Description copied from class: QueryToolChest

Returns a TypeReference object that is just passed through to Jackson in order to deserialize the results of this type of query.

Specified by:

getResultTypeReference in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Returns:

A TypeReference to indicate to Jackson what type of data will exist for this query

getCacheStrategy

public CacheStrategy<Result<SelectResultValue>,Object,SelectQuery> getCacheStrategy(SelectQuery query)

Description copied from class: QueryToolChest

Returns a CacheStrategy to be used to load data into the cache and remove it from the cache.

This is optional. If it returns null, caching is effectively disabled for the query.

Overrides:

getCacheStrategy in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Parameters:

query - The query whose results might be cached

Returns:

A CacheStrategy that can be used to populate and read from the Cache

preMergeQueryDecoration

public QueryRunner<Result<SelectResultValue>> preMergeQueryDecoration(QueryRunner<Result<SelectResultValue>> runner)

Description copied from class: QueryToolChest

Wraps a QueryRunner. The input QueryRunner is the QueryRunner as it exists *before* being passed to mergeResults().

In fact, the return value of this method is always passed to mergeResults, so it is equivalent to just implement this functionality as extra decoration on the QueryRunner during mergeResults().

In the interests of potentially simplifying these interfaces, the recommendation is to actually not override this method and instead apply anything that might be needed here in the mergeResults() call.

Overrides:

preMergeQueryDecoration in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Parameters:

runner - The runner to be wrapped

Returns:

The wrapped runner

filterSegments

public <T extends LogicalSegment> List<T> filterSegments(SelectQuery query,
                                                         List<T> segments)

Description copied from class: QueryToolChest

This method is called to allow the query to prune segments that it does not believe need to actually be queried. It can use whatever criteria it wants in order to do the pruning, it just needs to return the list of Segments it actually wants to see queried.

Overrides:

filterSegments in class QueryToolChest<Result<SelectResultValue>,SelectQuery>

Type Parameters:

T - A Generic parameter because Java is cool

Parameters:

query - The query being processed

segments - The list of candidate segments to be queried

Returns:

The list of segments to actually query