Package org.apache.druid.query

Class LookupDataSource

java.lang.Object
org.apache.druid.query.LeafDataSource
org.apache.druid.query.LookupDataSource
All Implemented Interfaces:
Cacheable, DataSource
public class LookupDataSource extends LeafDataSource
Represents a lookup.

Currently, this datasource is not actually queryable, and attempts to do so will lead to errors. It is here as a placeholder for a future time in which it will become queryable.

The "lookupName" referred to here should be provided by a LookupExtractorFactoryContainerProvider.

  • Constructor Details

    • LookupDataSource

      public LookupDataSource(String lookupName)

  • Method Details

    • getTableNames

      public Set<String> getTableNames()
      Description copied from interface: DataSource
      Returns the names of all table datasources involved in this query. Does not include names for non-tables, like lookups or inline datasources.

    • getLookupName

      public String getLookupName()

    • isCacheable

      public boolean isCacheable(boolean isBroker)
      Description copied from interface: DataSource
      Returns true if queries on this dataSource are cacheable at both the result level and per-segment level. Currently, dataSources that do not actually reference segments (like 'inline'), are not cacheable since cache keys are always based on segment identifiers.

    • isGlobal

      public boolean isGlobal()
      Description copied from interface: DataSource
      Decides if this datasource can be accessed globally.

      This means that all servers have a full copy of this datasource.

      Examples: inline table, lookup.

    • isProcessable

      public boolean isProcessable()
      Description copied from interface: DataSource
      Communicates that this DataSource can be directly used to run a Query.

      A Processable datasource must pack the necessary logic into the DataSource.createSegmentMapFunction(Query).

      Processable examples are: TableDataSource, InlineDataSource, FilteredDataSource. Non-processable ones are those which need further pre-processing before running them. examples are: QueryDataSource and join which are not supported directly.

    • getCacheKey

      public byte[] getCacheKey()
      Description copied from interface: DataSource
      Compute a cache key prefix for a data source. This includes the data sources that participate in the RHS of a join as well as any query specific constructs associated with join data source such as base table filter. This key prefix can be used in segment level cache or result level cache. The function can return following - Non-empty byte array - If there is join datasource involved and caching is possible. The result includes join condition expression, join type and cache key returned by joinable factory for each PreJoinableClause - NULL - There is a join but caching is not possible. It may happen if one of the participating datasource in the JOIN is not cacheable.
      Returns:
      the cache key to be used as part of query cache key

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object