比开源快30倍的自研SQL Parser设计与实践

selECT c1 From T1;
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public interface Replaceable {
    boolean replace(Node expr, Node target);
}


public class BetweenNode implements Replaceable {
    public Node            beginExpr;
    public Node            endExpr;
    
    @Override
    public int hashCode(){...}
    @Override
    public boolean equals(Object obj) {...}
    
    @Override
    public boolean replace(SQLExpr expr, SQLExpr target) {
        if (expr == beginExpr) {
            setBeginExpr(target);
            return true;
        }


        if (expr == endExpr) {
            setEndExpr(target);
            return true;
        }


        return false;
    }
}
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public abstract class Node {
    public abstract List<Node> getChildren()
}


public class BetweenNode extends Node {
    public Node            beginExpr;
    public Node            endExpr;
    
    @Override
    public List<Node> getChildren() {
        return Arrays.<Node>asList(beginExpr, this.endExpr);
    }
    
    @Override
    public BetweenNode clone() {
        BetweenNode x = new BetweenNode();
        if (beginExpr != null) {
            x.setBeginExpr(beginExpr.clone());
        }
        if (endExpr != null) {
            x.setEndExpr(endExpr.clone());
        }
        return x;
    }
    
    public void setBeginExpr(Node beginExpr) {
        if (beginExpr != null) {
            beginExpr.setParent(this);
        }
        this.beginExpr = beginExpr;
    }
    
    public void setEndExpr(Node endExpr) {
        if (endExpr != null) {
            endExpr.setParent(this);
        }
        this.endExpr = endExpr;
    }
}
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public interface InsertValueHandler {
    Object newRow() throws SQLException;
    void processInteger(Object row, int index, Number value);
    void processString(Object row, int index, String value);
    void processDate(Object row, int index, String value);
    void processDate(Object row, int index, java.util.Date value);
    void processTimestamp(Object row, int index, String value);
    void processTimestamp(Object row, int index, java.util.Date value);
    void processTime(Object row, int index, String value);
    void processDecimal(Object row, int index, BigDecimal value);
    void processBoolean(Object row, int index, boolean value);
    void processNull(Object row, int index);
    void processFunction(Object row, int index, String funcName, Object... values);
    void processRow(Object row);
    void processComplete();
}


public class BatchInsertHandler implements InsertValueHandler {
    ...
}


public class Application {
    BatchInsertHandler handler = new BatchInsertHandler();
    parser.parseInsertHeader(); // 头部：解析 insert into xxx values 部分
    parser.parseValues(handler); // 批量值：values (xxx), (xxx), (xxx) 部分
}
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-- 常量折叠示例
SELECT * FROM T1
WHERE c_week
  BETWEEN CAST(date_format(date_add('day', -day_of_week('20180605'),
                                   date('20180605')), '%Y%m&d') as bigint)
  AND CAST(date_format(date_add('day', -day_of_week('20180606'),
                                   date('20180606')), '%Y%m&d') as bigint)
                                   
------------折叠后-----------
SELECT * from T1
WHERE c_week BETWEEN 20180602 and 20180603
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-- 函数转换示例
SELECT * FROM T1
WHERE DATE_FORMAT(t1."pay_time", '%Y%m%d') >= '20180529'
    AND DATE_FORMAT(t1."pay_time", '%Y%m%d') <= '20180529'
    
-----------转化后, 更好利用索引------------
SELECT * FROM T1
WHERE t1."pay_time" >= '2018-05-29 00:00:00'
  AND t1."pay_time" < '2018-05-30 00:00:00'
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