Class ColumnReference

  • All Implemented Interfaces:
    Visitable

    public class ColumnReference
    extends ValueNode
    A ColumnReference represents a column in the query tree. The parser generates a ColumnReference for each column reference. A column reference could be a column in a base table, a column in a view (which could expand into a complex expression), or a column in a subquery in the FROM clause.
    • Field Detail

      • _columnName

        private java.lang.String _columnName
      • _qualifiedTableName

        private TableName _qualifiedTableName
      • tableNumber

        private int tableNumber
        The FromTable this column reference is bound to.
      • columnNumber

        private int columnNumber
        The column number in the underlying FromTable. But note source.
        See Also:
        source
      • origName

        private java.lang.String origName
      • _origTableNumber

        private int _origTableNumber
      • _origColumnNumber

        private int _origColumnNumber
      • tableNumberBeforeFlattening

        private int tableNumberBeforeFlattening
      • columnNumberBeforeFlattening

        private int columnNumberBeforeFlattening
      • replacesAggregate

        private boolean replacesAggregate
      • replacesWindowFunctionCall

        private boolean replacesWindowFunctionCall
      • nestingLevel

        private int nestingLevel
      • sourceLevel

        private int sourceLevel
      • scoped

        private boolean scoped
      • _mergeTableID

        private int _mergeTableID
        Columns mentioned by MERGE statements need to be associated the SOURCE or TARGET table
    • Constructor Detail

      • ColumnReference

        ColumnReference​(java.lang.String columnName,
                        TableName tableName,
                        int tokBeginOffset,
                        int tokEndOffset,
                        ContextManager cm)
        Constructor. This one is called by the parser where we could be dealing with delimited identifiers.
        Parameters:
        columnName - The name of the column being referenced
        tableName - The qualification for the column
        tokBeginOffset - begin position of token for the column name identifier from parser.
        tokEndOffset - end position of token for the column name identifier from parser.
        cm - The context manager
      • ColumnReference

        ColumnReference​(java.lang.String columnName,
                        TableName tableName,
                        ContextManager cm)
        Constructor.
        Parameters:
        columnName - The name of the column being referenced
        tableName - The qualification for the column
        cm - The context manager
    • Method Detail

      • toString

        public java.lang.String toString()
        Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.
        Overrides:
        toString in class ValueNode
        Returns:
        This object as a String
      • printSubNodes

        void printSubNodes​(int depth)
        Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.
        Overrides:
        printSubNodes in class QueryTreeNode
        Parameters:
        depth - The depth of this node in the tree
      • getCorrelated

        boolean getCorrelated()
        Return whether or not this CR is correlated.
        Returns:
        Whether or not this CR is correlated.
      • setNestingLevel

        void setNestingLevel​(int nestingLevel)
        Set the nesting level for this CR. (The nesting level at which the CR appears.)
        Parameters:
        nestingLevel - The Nesting level at which the CR appears.
      • getNestingLevel

        private int getNestingLevel()
        Get the nesting level for this CR.
        Returns:
        The nesting level for this CR.
      • setSourceLevel

        void setSourceLevel​(int sourceLevel)
        Set the source level for this CR. (The nesting level of the source of the CR.)
        Parameters:
        sourceLevel - The Nesting level of the source of the CR.
      • getSourceLevel

        int getSourceLevel()
        Get the source level for this CR.
        Returns:
        The source level for this CR.
      • markGeneratedToReplaceAggregate

        void markGeneratedToReplaceAggregate()
        Mark this node as being generated to replace an aggregate. (Useful for replacing aggregates in the HAVING clause with column references to the matching aggregate in the user's SELECT.
      • markGeneratedToReplaceWindowFunctionCall

        void markGeneratedToReplaceWindowFunctionCall()
        Mark this node as being generated to replace a window function call.
      • getGeneratedToReplaceAggregate

        boolean getGeneratedToReplaceAggregate()
        Determine whether or not this node was generated to replace an aggregate in the user's SELECT.
        Returns:
        boolean Whether or not this node was generated to replace an aggregate in the user's SELECT.
      • getGeneratedToReplaceWindowFunctionCall

        boolean getGeneratedToReplaceWindowFunctionCall()
        Determine whether or not this node was generated to replace a window function call in the user's SELECT.
        Returns:
        boolean Whether or not this node was generated to replace a window function call in the user's SELECT.
      • bindExpression

        ColumnReference bindExpression​(FromList fromList,
                                       SubqueryList subqueryList,
                                       java.util.List<AggregateNode> aggregates)
                                throws StandardException
        Bind this expression. This means binding the sub-expressions, as well as figuring out what the return type is for this expression. NOTE: We must explicitly check for a null FromList here, column reference without a FROM list, as the grammar allows the following: insert into t1 values(c1)
        Overrides:
        bindExpression in class ValueNode
        Parameters:
        fromList - The FROM list for the query this expression is in, for binding columns.
        subqueryList - The subquery list being built as we find SubqueryNodes
        aggregates - The aggregate list being built as we find AggregateNodes
        Returns:
        The new top of the expression tree.
        Throws:
        StandardException - Thrown on error
      • getSQLColumnName

        java.lang.String getSQLColumnName()
        Get the column name for purposes of error messages or debugging. This returns the column name as used in the SQL statement. Thus if it was qualified with a table, alias name that will be included.
        Returns:
        The column name in the form [[schema.]table.]column
      • getColumnName

        public java.lang.String getColumnName()
        Get the name of this column
        Overrides:
        getColumnName in class ValueNode
        Returns:
        The name of this column
      • getTableNumber

        int getTableNumber()
        Get the table number for this ColumnReference.
        Returns:
        int The table number for this ColumnReference
      • setTableNumber

        void setTableNumber​(int tableNumber)
        Set this ColumnReference to refer to the given table number.
        Parameters:
        tableNumber - The table number this ColumnReference will refer to
      • getTableName

        java.lang.String getTableName()
        Get the user-supplied table name of this column. This will be null if the user did not supply a name (for example, select a from t). The method will return B for this example, select b.a from t as b The method will return T for this example, select t.a from t
        Overrides:
        getTableName in class ValueNode
        Returns:
        The user-supplied name of this column. Null if no user- supplied name.
      • getSourceTableName

        java.lang.String getSourceTableName()
        Get the name of the underlying(base) table this column comes from, if any. Following example queries will all return T select a from t select b.a from t as b select t.a from t
        Returns:
        The name of the base table that this column comes from. Null if not a ColumnReference.
      • getSourceSchemaName

        java.lang.String getSourceSchemaName()
                                      throws StandardException
        Get the name of the schema for the Column's base table, if any. Following example queries will all return APP (assuming user is in schema APP) select t.a from t select b.a from t as b select app.t.a from t
        Returns:
        The name of the schema for Column's base table. If the column is not in a schema (i.e. is a derived column), it returns NULL.
        Throws:
        StandardException
      • updatableByCursor

        public boolean updatableByCursor()
        Is the column wirtable by the cursor or not. (ie, is it in the list of FOR UPDATE columns list)
        Overrides:
        updatableByCursor in class ValueNode
        Returns:
        TRUE, if the column is a base column of a table and is writable by cursor.
      • getQualifiedTableName

        public TableName getQualifiedTableName()
        Return the table name as the node it is.
        Returns:
        the column's table name.
      • setQualifiedTableName

        void setQualifiedTableName​(TableName tableName)
      • getColumnNumber

        int getColumnNumber()
        Get the column number for this ColumnReference.
        Returns:
        int The column number for this ColumnReference
      • setColumnNumber

        void setColumnNumber​(int colNum)
        Set the column number for this ColumnReference. This is used when scoping predicates for pushdown.
        Parameters:
        colNum - The new column number.
      • getSource

        ResultColumn getSource()
        Get the source this columnReference
        Returns:
        The source of this columnReference
      • setSource

        void setSource​(ResultColumn source)
        Set the source this columnReference
        Parameters:
        source - The source of this columnReference
      • putAndsOnTop

        ValueNode putAndsOnTop()
                        throws StandardException
        Do the 1st step in putting an expression into conjunctive normal form. This step ensures that the top level of the expression is a chain of AndNodes.
        Overrides:
        putAndsOnTop in class ValueNode
        Returns:
        The modified expression
        Throws:
        StandardException - Thrown on error
      • categorize

        boolean categorize​(JBitSet referencedTabs,
                           boolean simplePredsOnly)
        Categorize this predicate. Initially, this means building a bit map of the referenced tables for each predicate. If the source of this ColumnReference (at the next underlying level) is not a ColumnReference or a VirtualColumnNode then this predicate will not be pushed down. For example, in: select * from (select 1 from s) a (x) where x = 1 we will not push down x = 1. NOTE: It would be easy to handle the case of a constant, but if the inner SELECT returns an arbitrary expression, then we would have to copy that tree into the pushed predicate, and that tree could contain subqueries and method calls. Also, don't allow a predicate to be pushed down if it contains a ColumnReference that replaces an aggregate. This can happen if the aggregate is in the HAVING clause. In this case, we would be pushing the predicate into the SelectNode that evaluates the aggregate, which doesn't make sense, since the having clause is supposed to be applied to the result of the SelectNode. This also goes for column references that replaces a window function. RESOLVE - revisit this issue once we have views.
        Overrides:
        categorize in class ValueNode
        Parameters:
        referencedTabs - JBitSet with bit map of referenced FromTables
        simplePredsOnly - Whether or not to consider method calls, field references and conditional nodes when building bit map
        Returns:
        boolean Whether or not source.expression is a ColumnReference or a VirtualColumnNode or a ConstantNode.
      • remapColumnReferences

        void remapColumnReferences()
        Remap all of the ColumnReferences in this expression tree to point to the ResultColumn that is 1 level under their current source ResultColumn. This is useful for pushing down single table predicates. RESOLVE: Once we start pushing join clauses, we will need to walk the ResultColumn/VirtualColumnNode chain for them to remap the references.
      • unRemapColumnReferences

        void unRemapColumnReferences()
      • hasBeenRemapped

        protected boolean hasBeenRemapped()
        Returns true if this ColumnReference has been remapped; false otherwise.
        Returns:
        Whether or not this ColumnReference has been remapped.
      • getSourceResultColumn

        ResultColumn getSourceResultColumn()
        Description copied from class: ValueNode
        Get the source for this ValueNode.
        Overrides:
        getSourceResultColumn in class ValueNode
        Returns:
        The source of this ValueNode, null if this node is not sourced by a column.
      • getTablesReferenced

        void getTablesReferenced​(JBitSet refs)
        Update the table map to reflect the source of this CR.
        Parameters:
        refs - The table map.
      • isCloneable

        boolean isCloneable()
        Return whether or not this expression tree is cloneable.
        Overrides:
        isCloneable in class ValueNode
        Returns:
        boolean Whether or not this expression tree is cloneable.
      • generateExpression

        void generateExpression​(ExpressionClassBuilder acb,
                                MethodBuilder mb)
                         throws StandardException
        ColumnReference's are to the current row in the system. This lets us generate a faster get that simply returns the column from the current row, rather than getting the value out and returning that, only to have the caller (in the situations needed) stuffing it back into a new column holder object. We will assume the general generate() path is for getting the value out, and use generateColumn() when we want to keep the column wrapped.
        Overrides:
        generateExpression in class ValueNode
        Parameters:
        acb - The ExpressionClassBuilder for the class being built
        mb - The method the expression will go into
        Throws:
        StandardException - Thrown on error
      • getSchemaName

        java.lang.String getSchemaName()
        Get the user-supplied schema name of this column. This will be null if the user did not supply a name (for example, select t.a from t). Another example for null return value (for example, select b.a from t as b). But for following query select app.t.a from t, this will return APP Code generation of aggregate functions relies on this method
        Overrides:
        getSchemaName in class ValueNode
        Returns:
        The user-supplied schema name of this column. Null if no user- supplied name.
      • getOrderableVariantType

        protected int getOrderableVariantType()
        Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)
        Overrides:
        getOrderableVariantType in class ValueNode
        Returns:
        The variant type for the underlying expression.
      • pointsToColumnReference

        boolean pointsToColumnReference()
        Return whether or not the source of this ColumnReference is itself a ColumnReference.
        Returns:
        Whether or not the source of this ColumnReference is itself a ColumnReference.
      • getTypeServices

        DataTypeDescriptor getTypeServices()
        The type of a ColumnReference is the type of its source unless the source is null then it is the type that has been set on this node.
        Overrides:
        getTypeServices in class ValueNode
        Returns:
        The DataTypeServices from this ValueNode. This may be null if the node isn't bound yet.
      • getSourceResultSet

        protected ResultSetNode getSourceResultSet​(int[] colNum)
                                            throws StandardException
        Find the source result set for this ColumnReference and return it. Also, when the source result set is found, return the position (within the source result set's RCL) of the column referenced by this ColumnReference. The position is returned vai the colNum parameter.
        Parameters:
        colNum - Place to store the position of the column to which this ColumnReference points (position is w.r.t the source result set).
        Returns:
        The source result set for this ColumnReference; null if there is no source result set.
        Throws:
        StandardException
      • isEquivalent

        boolean isEquivalent​(ValueNode o)
                      throws StandardException
        Description copied from class: ValueNode
        Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

        This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

        Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

        One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

        SELECT c1+c2 FROM t1 GROUP BY c1+c2

        In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

        • The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
        • If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
        • If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
        • When comparing SQL NULLs in this context, they are considered to be equivalent.
        • If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.
        Specified by:
        isEquivalent in class ValueNode
        Parameters:
        o - the node to compare this ValueNode against.
        Returns:
        true if the two nodes are equivalent, false otherwise.
        Throws:
        StandardException
      • markAsScoped

        protected void markAsScoped()
        Mark this column reference as "scoped", which means that it was created (as a clone of another ColumnReference) to serve as the left or right operand of a scoped predicate.
      • isScoped

        protected boolean isScoped()
        Return whether or not this ColumnReference is scoped.
      • setMergeTableID

        void setMergeTableID​(int mergeTableID)
        Associate this column with a SOURCE or TARGET table of a MERGE statement
      • prettyPrintMergeTableID

        private java.lang.String prettyPrintMergeTableID​(int mergeTableID)
      • getMergeTableID

        int getMergeTableID()
        Get the MERGE table (SOURCE or TARGET) associated with this column
      • acceptChildren

        void acceptChildren​(Visitor v)
                     throws StandardException
        Description copied from class: QueryTreeNode
        Accept a visitor on all child nodes. All sub-classes that add fields that should be visited, should override this method and call accept(v) on all visitable fields, as well as super.acceptChildren(v) to make sure all visitable fields defined by the super-class are accepted too.
        Overrides:
        acceptChildren in class QueryTreeNode
        Parameters:
        v - the visitor
        Throws:
        StandardException - on errors raised by the visitor