Query Splitter

Query Splitter Output

$ java -cp fdb-sql-parser-1.2.0.jar:. QuerySplitter "select * from a,b where (a.name='xyz' or a.id>5 ) and (b.name='abc' or b.id=5)"
original: select * from a,b where (a.name='xyz' or a.id>5 ) and (b.name='abc' or b.id=5)
unparsed: SELECT * FROM a, b WHERE ((a.name = 'xyz') OR (a.id > 5)) AND ((b.name = 'abc') OR (b.id = 5))
table a: SELECT * FROM a WHERE ((a.name = 'xyz') OR (a.id > 5)) AND (TRUE OR TRUE)
table b: SELECT * FROM b WHERE (TRUE OR TRUE) AND ((b.name = 'abc') OR (b.id = 5))

QuerySplitter.java

import com.foundationdb.sql.*;
import com.foundationdb.sql.parser.*;
import com.foundationdb.sql.unparser.*;

import java.util.*;

public class QuerySplitter
{
    public static void main(String[] args) throws Exception {
        SQLParser parser = new SQLParser();
        NodeToString nodeToString = new NodeToString();
        for(String s : args) {
            StatementNode stmt = parser.parseStatement(s);
            System.out.println("original: " + s);
            System.out.println("unparsed: " + nodeToString.toString(stmt));
            TableFinder finder = new TableFinder();
            stmt.accept(finder);
            for(TableName tn : finder.tableNames) {
                QueryTreeNode copy = parser.getNodeFactory().copyNode(stmt, parser);
                copy.accept(new TableKeeper(tn));
                System.out.println("table " + tn + ": " + nodeToString.toString(copy));
            }
        }
    }

    private static class TableFinder implements Visitor
    {
        public List<TableName> tableNames = new ArrayList<>();

        public Visitable visit(Visitable node) throws StandardException {
            if(node instanceof FromList) {
                FromList fl = (FromList)node;
                for(int i = 0; i < fl.size(); ++i) {
                    tableNames.add(fl.get(i).getTableName());
                }
            }
            return node;
        }

        public boolean visitChildrenFirst(Visitable node) {
            return false;
        }

        public boolean stopTraversal() {
            return false;
        }

        public boolean skipChildren(Visitable node) throws StandardException {
            return false;
        }
    }

    private static class TableKeeper implements Visitor
    {
        private final TableName keepTable;

        public TableKeeper(TableName keepTable) {
            this.keepTable = keepTable;
        }

        private boolean eliminate(ValueNode valueNode) {
            if(valueNode instanceof ColumnReference) {
                return !keepTable.equals(((ColumnReference)valueNode).getTableNameNode());
            }
            return false;
        }

        private ValueNode newTrueNode() throws StandardException {
            BooleanConstantNode boolNode = new BooleanConstantNode();
            boolNode.setNodeType(NodeTypes.BOOLEAN_CONSTANT_NODE);
            boolNode.init(Boolean.TRUE);
            return boolNode;
        }

        public Visitable visit(Visitable node) throws StandardException {
            if(node instanceof FromList) {
                FromList fl = (FromList)node;
                Iterator<FromTable> it = fl.iterator();
                while(it.hasNext()) {
                    FromTable ft = it.next();
                    if(!keepTable.equals(ft.getTableName())) {
                        it.remove();
                    }
                }
            }
            else if(node instanceof BinaryRelationalOperatorNode) {
                BinaryRelationalOperatorNode relNode = (BinaryRelationalOperatorNode)node;
                if(eliminate(relNode.getLeftOperand()) || eliminate(relNode.getRightOperand())) {
                    node = newTrueNode();
                }
            }
            return node;
        }

        public boolean visitChildrenFirst(Visitable node) {
            return false;
        }

        public boolean stopTraversal() {
            return false;
        }

        public boolean skipChildren(Visitable node) throws StandardException {
            return false;
        }
    }
}