The newest ES 5.0 routing algorithm underlying implementation

Http://www.cnblogs.com/bonelee/p/6078947.html analyzes the implementation of ES bulk, where the routing code:

Shardid Shardid = Clusterservice. operationrouting (). Indexshards (clusterstate, concreteindex, Request . ID (), request. Routing ()). Shardid ();

Its implementation: https://github.com/elastic/elasticsearch/blob/master/core/src/main/java/org/elasticsearch/cluster/routing/ Operationrouting.java

Public Sharditerator indexshards (clusterstate clusterstate, string index, string id, @Nullable string Routing) {return  shards (clusterstate, index, id, routing). shardsit ();        } protected  indexshardroutingtable shards (clusterstate clusterstate, string index, string id, string Routing) {        int shardid =  generateshardid (indexmetadata (clusterstate, index), id, routing);    return  clusterstate.getroutingtable (). shardroutingtable (index, shardid); } static int  generateshardid (indexmetadata indexmetadata, string id, @Nullable string Routing) {final int  Hash if (routing = = null ) {hash =  murmur3hashfunction.hash (id);} else  {hash =  murmur3hashfunction.ha SH (routing); }//we don ' t use imd#getnumberofshards since the index might has been shrunk such that we need to use the size//of the Ori Ginal Index to hash documents return Math.floormod (hash, indexmetadata.getroutingnumshards ())/ Indexmetadata.getroutingfactor (); }

You can see that the latest ES code implementation routes Are:

Math.floormod (hash, indexmetadata.getroutingnumshards ())/indexmetadata.getroutingfactor ();

In https://github.com/elastic/elasticsearch/blob/master/core/src/main/java/org/elasticsearch/cluster/metadata/ Indexmetadata.java can be seen in Getroutingfactor implementations:

    /**     * Returns The routing factor for this Index. The default is <tt>1</tt>.     *     * @see #getRoutingFactor (indexmetadata, int) for details     */public    int getroutingfactor () {        return routingfactor;    } 

In the constructor are:

        Assert numberofshards * Routingfactor = = routingnumshards:  routingnumshards + "must Be a multiple of" + NUMBEROFSH Ards

anyway, The default is 1, that is, all shard nodes will be responsible for routing!

beware, the ES2.4 version of the routing implementation: https://github.com/elastic/elasticsearch/blob/2.4/core/src/main/java/org/elasticsearch/cluster/routing/

@SuppressForbidden (reason = "math#abs is trappy")    Private intgenerateshardid (clusterstate clusterstate, string index, string type, string id, @Nullable string Routing) {I Ndexmetadata Indexmetadata=clusterstate.metadata (). Index (index); if(indexmetadata = =NULL) {            Throw Newindexnotfoundexception (index); }        FinalVersion createdversion =indexmetadata.getcreationversion (); FinalHashfunction hashfunction =indexmetadata.getroutinghashfunction (); Final BooleanUsetype =Indexmetadata.getroutingusetype (); Final inthash; if(routing = =NULL) {            if(!Usetype) {hash=Hash (hashfunction, id); } Else{hash=Hash (hashfunction, type, id); }        } Else{hash=Hash (hashfunction, routing); }        if(createdversion.onorafter (version.v_2_0_0_beta1)) {returnmathutils.mod (hash, indexmetadata.getnumberofshards ()); } Else {            returnMath.Abs (hash%Indexmetadata.getnumberofshards ()); }    }

    @Deprecated    protectedint  hash (hashfunction hashfunction, String type, String id) {        ifnull | | "_all". Equals (type)) {            thrownew illegalargumentexception ("Can ' t route an Operation with no type and have type part of the routing (for backward Comp);        }         return hashfunction.hash (type, id);    }

And the hash function is implemented by:

Djbhashfunction.java

Simplehashfunction.java

Murmur3hashfunction.java

Three KINDS.

Murmur3hashfunction.java

The newest ES 5.0 routing algorithm underlying implementation