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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-3572) Support FETCH NEXT| n ROWS from Cursor
Date Wed, 05 Apr 2017 18:49:41 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-3572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15957427#comment-15957427
] 

ASF GitHub Bot commented on PHOENIX-3572:
-----------------------------------------

Github user JamesRTaylor commented on a diff in the pull request:

    https://github.com/apache/phoenix/pull/229#discussion_r109997991
  
    --- Diff: phoenix-core/src/main/java/org/apache/phoenix/iterate/CursorResultIterator.java
---
    @@ -0,0 +1,75 @@
    +/*
    + * 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 org.apache.phoenix.schema.tuple.Tuple;
    +import org.apache.phoenix.util.CursorUtil;
    +
    +import java.sql.SQLException;
    +import java.util.List;
    +
    +public class CursorResultIterator implements ResultIterator {
    +    private String cursorName;
    +    private PeekingResultIterator delegate;
    +    //TODO Configure fetch size from FETCH call
    +    private int fetchSize = 0;
    +    private int rowsRead = 0;
    +    public CursorResultIterator(PeekingResultIterator delegate, String cursorName) {
    +        this.delegate = delegate;
    +        this.cursorName = cursorName;
    +    }
    +
    +    @Override
    +    public Tuple next() throws SQLException {
    +    	if(!CursorUtil.moreValues(cursorName)){
    +    	    return null;
    +        } else if (fetchSize == rowsRead) {
    +            return null;
    +    	}
    +
    +        Tuple next = delegate.next();
    +        CursorUtil.updateCursor(cursorName,next, delegate.peek());
    +        rowsRead++;
    +        return next;
    +    }
    +    
    +    @Override
    +    public void explain(List<String> planSteps) {
    +        delegate.explain(planSteps);
    +        planSteps.add("CLIENT CURSOR " + cursorName);
    +    }
    +
    +    @Override
    +    public String toString() {
    +        return "CursorResultIterator [cursor=" + cursorName + "]";
    +    }
    +
    +    @Override
    +    public void close() throws SQLException {
    +        //NOP
    --- End diff --
    
    Does this need to call delegate.close()? If not, what closes the underlying query?


> Support FETCH NEXT| n ROWS from Cursor
> --------------------------------------
>
>                 Key: PHOENIX-3572
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-3572
>             Project: Phoenix
>          Issue Type: Sub-task
>            Reporter: Biju Nair
>            Assignee: Biju Nair
>
> Implement required changes to support 
> - {{DECLARE}} and {{OPEN}} a cursor
> - query {{FETCH NEXT | n ROWS}} from the cursor
> - {{CLOSE}} the cursor
> Based on the feedback in [PR #192|https://github.com/apache/phoenix/pull/192], implement
the changes using {{ResultSet}}.



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