Class DeleteNode

  • All Implemented Interfaces:
    Visitable

    class DeleteNode
    extends DMLModStatementNode
    A DeleteNode represents a DELETE statement. It is the top-level node for the statement. For positioned delete, there may be no from table specified. The from table will be derived from the cursor specification of the named cursor.
    • Field Detail

      • deferred

        private boolean deferred
      • dependentConstantActions

        private ConstantAction[] dependentConstantActions
      • cascadeDelete

        private boolean cascadeDelete
    • Constructor Detail

      • DeleteNode

        DeleteNode​(TableName targetTableName,
                   ResultSetNode queryExpression,
                   MatchingClauseNode matchingClause,
                   ContextManager cm)
        Constructor for a DeleteNode.
        Parameters:
        targetTableName - The name of the table to delete from
        queryExpression - The query expression that will generate the rows to delete from the given table
        matchingClause - Non-null if this DML is part of a MATCHED clause of a MERGE statement.
        cm - The context manager
    • Method Detail

      • bindStatement

        public void bindStatement()
                           throws StandardException
        Bind this DeleteNode. This means looking up tables and columns and getting their types, and figuring out the result types of all expressions, as well as doing view resolution, permissions checking, etc.

        If any indexes need to be updated, we add all the columns in the base table to the result column list, so that we can use the column values as look-up keys for the index rows to be deleted. Binding a delete will also massage the tree so that the ResultSetNode has column containing the RowLocation of the base row.

        Overrides:
        bindStatement in class StatementNode
        Throws:
        StandardException - Thrown on error
      • getPrivType

        int getPrivType()
        Description copied from class: DMLStatementNode
        Return default privilege needed for this node. Other DML nodes can override this method to set their own default privilege.
        Overrides:
        getPrivType in class DMLStatementNode
        Returns:
        true if the statement is atomic
      • generate

        void generate​(ActivationClassBuilder acb,
                      MethodBuilder mb)
               throws StandardException
        Code generation for delete. The generated code will contain: o A static member for the (xxx)ResultSet with the RowLocations o The static member will be assigned the appropriate ResultSet within the nested calls to get the ResultSets. (The appropriate cast to the (xxx)ResultSet will be generated.) o The CurrentRowLocation() in SelectNode's select list will generate a new method for returning the RowLocation as well as a call to that method which will be stuffed in the call to the ProjectRestrictResultSet. o In case of referential actions, this function generate an array of resultsets on its dependent tables.
        Overrides:
        generate in class QueryTreeNode
        Parameters:
        acb - The ActivationClassBuilder for the class being built
        mb - The execute() method to be built
        Throws:
        StandardException - Thrown on error
      • getStatementType

        protected final int getStatementType()
        Return the type of statement, something from StatementType.
        Overrides:
        getStatementType in class QueryTreeNode
        Returns:
        the type of statement
      • getReadMap

        public FormatableBitSet getReadMap​(DataDictionary dd,
                                           TableDescriptor baseTable)
                                    throws StandardException
        Gets the map of all columns which must be read out of the base table. These are the columns needed to: o maintain indices o maintain foreign keys The returned map is a FormatableBitSet with 1 bit for each column in the table plus an extra, unsued 0-bit. If a 1-based column id must be read from the base table, then the corresponding 1-based bit is turned ON in the returned FormatableBitSet.
        Parameters:
        dd - the data dictionary to look in
        baseTable - the base table descriptor
        Returns:
        a FormatableBitSet of columns to be read out of the base table
        Throws:
        StandardException - Thrown on error
      • getDependentTableNode

        private StatementNode getDependentTableNode​(java.lang.String schemaName,
                                                    java.lang.String tableName,
                                                    int refAction,
                                                    ColumnDescriptorList cdl)
                                             throws StandardException
        In case of referential actions, we require to perform DML (UPDATE or DELETE) on the dependent tables. Following function returns the DML Node for the dependent table.
        Throws:
        StandardException
      • optimizeStatement

        public void optimizeStatement()
                               throws StandardException
        Description copied from class: DMLModStatementNode
        Generate an optimized QueryTree from a bound QueryTree. Actually, it can annotate the tree in place rather than generate a new tree, but this interface allows the root node of the optimized QueryTree to be different from the root node of the bound QueryTree. For non-optimizable statements, this method is a no-op. Throws an exception if the tree is not bound, or if the binding is out of date.
        Overrides:
        optimizeStatement in class DMLModStatementNode
        Throws:
        StandardException - Thrown on failure
      • getDeleteReadMap

        private static FormatableBitSet getDeleteReadMap​(TableDescriptor baseTable,
                                                         java.util.List<ConglomerateDescriptor> conglomerates,
                                                         TriggerDescriptorList relevantTriggers,
                                                         boolean[] needsDeferredProcessing)
                                                  throws StandardException
        Builds a bitmap of all columns which should be read from the Store in order to satisfy an DELETE statement. 1) finds all indices on this table 2) adds the index columns to a bitmap of affected columns 3) adds the index descriptors to a list of conglomerate descriptors. 4) finds all DELETE triggers on the table 5) if there are any DELETE triggers, then do one of the following a)If all of the triggers have MISSING referencing clause, then that means that the trigger actions do not have access to before and after values. In that case, there is no need to blanketly decide to include all the columns in the read map just because there are triggers defined on the table. b)Since one/more triggers have REFERENCING clause on them, get all the columns because we don't know what the user will ultimately reference. 6) adds the triggers to an evolving list of triggers
        Parameters:
        conglomerates - OUT: list of affected indices
        relevantTriggers - IN/OUT. Passed in as an empty list. Filled in as we go.
        needsDeferredProcessing - IN/OUT. true if the statement already needs deferred processing. set while evaluating this routine if a trigger requires deferred processing
        Returns:
        a FormatableBitSet of columns to be read out of the base table
        Throws:
        StandardException - Thrown on error