elasticsearch里的search_type
elasticsearch里面的search_type共有如下几种:
The type of the search operation to perform. Can be
dfs_query_then_fetch,
dfs_query_and_fetch,
query_then_fetch,
query_and_fetch.
public enum SearchType { /** * Same as {@link #QUERY_THEN_FETCH}, except for an initial scatter phase which goes and computes the distributed * term frequencies for more accurate scoring. */ DFS_QUERY_THEN_FETCH((byte) 0), /** * The query is executed against all shards, but only enough information is returned (not the document content). * The results are then sorted and ranked, and based on it, only the relevant shards are asked for the actual * document content. The return number of hits is exactly as specified in size, since they are the only ones that * are fetched. This is very handy when the index has a lot of shards (not replicas, shard id groups). */ QUERY_THEN_FETCH((byte) 1), /** * Same as {@link #QUERY_AND_FETCH}, except for an initial scatter phase which goes and computes the distributed * term frequencies for more accurate scoring. */ DFS_QUERY_AND_FETCH((byte) 2), /** * The most naive (and possibly fastest) implementation is to simply execute the query on all relevant shards * and return the results. Each shard returns size results. Since each shard already returns size hits, this * type actually returns size times number of shards results back to the caller. */ QUERY_AND_FETCH((byte) 3), /** * Performs scanning of the results which executes the search without any sorting. * It will automatically start scrolling the result set. */ SCAN((byte) 4), /** * Only counts the results, will still execute facets and the like. */ COUNT((byte) 5); /** * The default search type ({@link #QUERY_THEN_FETCH}. */ public static final SearchType DEFAULT = QUERY_THEN_FETCH; } |
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