Package com.yahoo.search.federation

Class FederationSearcher

java.lang.Object
com.yahoo.component.AbstractComponent
com.yahoo.component.chain.ChainedComponent
com.yahoo.processing.Processor
com.yahoo.search.Searcher
com.yahoo.search.searchchain.ForkingSearcher
com.yahoo.search.federation.FederationSearcher
All Implemented Interfaces:
com.yahoo.component.Component, com.yahoo.component.Deconstructable, Comparable<com.yahoo.component.Component>
public class FederationSearcher extends ForkingSearcher
This searcher takes a set of sources, looks them up in config and fire off the correct searchchains.
Author:
Arne Bergene Fossaa, Tony Vaagenes, bratseth

  • Field Details

    • SOURCENAME

      public static final com.yahoo.processing.request.CompoundName SOURCENAME
      The name of the query property containing the source name added to the query to each source by this

    • PROVIDERNAME

      public static final com.yahoo.processing.request.CompoundName PROVIDERNAME

    • FEDERATION

      public static final String FEDERATION
      See Also:

    • LOG_COUNT_PREFIX

      public static final String LOG_COUNT_PREFIX
      See Also:

  • Constructor Details

    • FederationSearcher

      @Inject public FederationSearcher(FederationConfig config, com.yahoo.component.provider.ComponentRegistry<TargetSelector> targetSelectors)

    • FederationSearcher

      public FederationSearcher(com.yahoo.component.ComponentId id, SearchChainResolver searchChainResolver)

  • Method Details

    • search

      public Result search(Query query, Execution execution)
      Description copied from class: Searcher
      Override this to implement your searcher.

      Searcher implementation subclasses will, depending on their type of logic, do one of the following:

      • Query processors: Access the query, then call execution.search and return the result
      • Result processors: Call execution.search to get the result, access it and return
      • Sources (which produces results): Create a result, add the desired hits and return it.
      • Federators (which forwards the search to multiple subchains): Call search on the desired subchains in parallel and get the results. Combine the results to one and return it.
      • Workflows: Call execution.search as many times as desired, using different queries. Eventually return a result.

      Hits come in two kinds - concrete hits are actual content of the kind requested by the user, meta hits are hits which provides information about the collection of hits, on the query, the service and so on.

      The query specifies a window into a larger result list that must be returned from the searcher through hits and offset; Searchers which returns list of hits in the top level in the result must return at least hits number of hits (or if impossible; all that are available), starting at the given offset. In addition, searchers are allowed to return any number of meta hits (although this number is expected to be low). For hits contained in nested hit groups, the concept of a window defined by hits and offset is not well defined and does not apply.

      Error handling in searchers:

      • Unexpected events: Throw any RuntimeException. This query will fail with the exception message, and the error will be logged
      • Expected events: Create (new Result(Query, ErrorMessage) or add result.setErrorIfNoOtherErrors(ErrorMessage) an error message to the Result.
      • Recoverable user errors: Add a FeedbackHit explaining the condition and how to correct it.
      Specified by:
      search in class Searcher
      Parameters:
      query - the query
      Returns:
      the result of making this query

    • getSearchChainsForwarded

      public Collection<ForkingSearcher.CommentedSearchChain> getSearchChainsForwarded(SearchChainRegistry registry)
      Description copied from class: ForkingSearcher
      Returns which searchers this searcher may forward to, for debugging and tracing
      Specified by:
      getSearchChainsForwarded in class ForkingSearcher

    • fill

      public void fill(Result result, String summaryClass, Execution execution)
      Description copied from class: Searcher
      Fill hit properties with data using the given summary class. Calling this on already filled results has no cost.

      This needs to be overridden by federating searchers to contact search sources again by propagating the fill call down through the search chain, and by source searchers which talks to fill capable backends to request the data to be filled. Other searchers do not need to override this.

      Overrides:
      fill in class Searcher
      Parameters:
      result - the result to fill
      summaryClass - the name of the collection of fields to fetch the values of, or null to use the default

    • defaultSearchChains

      public com.yahoo.errorhandling.Results<SearchChainInvocationSpec,UnresolvedSearchChainException> defaultSearchChains(Properties sourceToProviderMap)