HBase coprocessor coprocessor

is divided into two types

1. Observer observers are equivalent to triggers
   

2. Endpoint terminal equivalent to stored procedure

The following observer implements the query before replacing the row key with Jack's KeyValue

Import java.io.ioexception;import java.util.list;import org.apache.hadoop.hbase.keyvalue;import  org.apache.hadoop.hbase.client.Get;import org.apache.hadoop.hbase.coprocessor.BaseRegionObserver; import org.apache.hadoop.hbase.coprocessor.observercontext;import  org.apache.hadoop.hbase.coprocessor.regioncoprocessorenvironment;import  org.apache.hadoop.hbase.util.bytes;public class regionobservertest extends  baseregionobserver {    private static byte[] fixed_rowkey =   "Jack". GetBytes ();     @Override     public void postget (observercontext<regioncoprocessorenvironment> c,             get get, list<keyvalue> result)  throws IOException  {        if  (Bytes.equals (Get.getrow (),  fixed_rowkEY))  {            keyvalue kv =  new keyvalue (Get.getrow (),  bytes.tobytes ("Time"),                     bytes.tobytes ("Time"),  Bytes.tobytes (system                             .currenttimemillis ()));             result.add (KV);         }    }}

Load coprocessor Command

Disable ' students ' alter ' students ', ' coprocessor ' = ' hdfs://ns1/coprocessor.jar|com.hbase.regionobservertest| | ' Enable ' Students '

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HBase coprocessor coprocessor