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From ankitsinghal <...@git.apache.org>
Subject [GitHub] phoenix pull request: PHOENIX-2722 support mysql limit,offset clau...
Date Wed, 06 Apr 2016 09:45:10 GMT
Github user ankitsinghal commented on a diff in the pull request:

    https://github.com/apache/phoenix/pull/154#discussion_r58678464
  
    --- Diff: phoenix-core/src/main/java/org/apache/phoenix/iterate/OffsetScanGrouper.java
---
    @@ -0,0 +1,44 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + * http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.phoenix.iterate;
    +
    +import java.util.List;
    +
    +import org.apache.hadoop.hbase.client.Scan;
    +import org.apache.phoenix.compile.QueryPlan;
    +
    +/**
    + * Default implementation that creates a scan group if a plan is row key ordered (which
requires a merge sort),
    + * or if a scan crosses a region boundary and the table is salted or a local index. 
 
    + */
    +public class OffsetScanGrouper implements ParallelScanGrouper {
    --- End diff --
    
    It seems for serialIterators also , we use DefaultParallelScanGrouper for splitting scans
in groups by condition `(isSalted || table.getIndexType() == IndexType.LOCAL) && ScanUtil.shouldRowsBeInRowKeyOrder(orderBy,
context)` and run each group in one thread.
    
    Anyways, I have modified the plan to run offset on server by including this condition
and re-use the DefaultParallelScanGrouper


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