Class CoalesceFunctionNode

java.lang.Object

org.apache.derby.impl.sql.compile.QueryTreeNode

org.apache.derby.impl.sql.compile.ValueNode

org.apache.derby.impl.sql.compile.CoalesceFunctionNode

All Implemented Interfaces:

Visitable

class CoalesceFunctionNode
extends ValueNode

This node represents coalesce/value function which returns the first argument that is not null. The arguments are evaluated in the order in which they are specified, and the result of the function is the first argument that is not null. The result can be null only if all the arguments can be null. The selected argument is converted, if necessary, to the attributes of the result. SQL Reference Guide for DB2 has section titled "Rules for result data types" at the following url http://publib.boulder.ibm.com/infocenter/db2help/index.jsp?topic=/com.ibm.db2.udb.doc/admin/r0008480.htm I have constructed following table based on various tables and information under "Rules for result data types" This table has FOR BIT DATA TYPES broken out into separate columns for clarity Note that are few differences between Derby and DB2 1)there are few differences between what data types are considered compatible In DB2, CHAR FOR BIT DATA data types are compatible with CHAR data types ie in addition to following table, CHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA ie in addition to following table, VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA ie in addition to following table, LONG VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA ie in addition to following table, CHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP ie in addition to following table, VARCHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP 2)few data types do not have matching precision in Derby and DB2 In DB2, precision of TIME is 8. In Derby, precision of TIME is 0. In DB2, precision,scale of TIMESTAMP is 26,6. In Derby, precision of TIMESTAMP is 0,0. In DB2, precision of DOUBLE is 15. In Derby, precision of DOUBLE is 52. In DB2, precision of REAL is 23. In Derby, precision of REAL is 7. In DB2, precision calculation equation is incorrect when we have int and decimal arguments. The equation should be p=x+max(w-x,10) since precision of integer is 10 in both DB2 and Derby. Instead, DB2 has p=x+max(w-x,11) Types. S I B D R D C V L C V L C D T T B M N I E E O H A O H A O L A I I L A T G C A U A R N A R N O T M M O L E I I L B R C G R C G B E E E B L G N M L H V . H V S I E T A E A A B A A T N R L R R I R R A T C T . . M H B B P A I I R T T SMALLINT { "SMALLINT", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, INTEGER { "INTEGER", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, BIGINT { "BIGINT", "BIGINT", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, DECIMAL { "DECIMAL", "DECIMAL", "DECIMAL", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, REAL { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "REAL", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, DOUBLE { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, CHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CHAR", "VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" }, VARCHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "VARCHAR", "VARCHAR","LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" }, LONGVARCHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG VARCHAR", "LONG VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" }, CHAR FOR BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, VARCH. BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT VARYING", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, LONGVAR. BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG BIT VARYING", "LONG BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" }, CLOB { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CLOB", "CLOB", "CLOB", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" }, DATE { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "DATE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "ERROR", "ERROR", "ERROR" }, TIME { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "TIME", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "ERROR", "ERROR" }, TIMESTAMP { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "TIMESTAMP", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "ERROR" }, BLOB { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BLOB" }

Field Summary

Fields

Modifier and Type	Field	Description
(package private) ValueNodeList	argumentsList
private int	firstNonParameterNodeIdx	The generated method will generate code to call coalesce on this non-parameter argument.
(package private) String	functionName

Fields inherited from class ValueNode

transformed

Fields inherited from class QueryTreeNode

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Constructor Summary

Constructors

Constructor	Description
CoalesceFunctionNode(String functionName, ValueNodeList argumentsList, ContextManager cm)	Constructor for a CoalesceFunctionNode

Method Summary

Modifier and Type	Method	Description
(package private) void	acceptChildren(Visitor v)	Accept the visitor for all visitable children of this node.
(package private) ValueNode	bindExpression(FromList fromList, SubqueryList subqueryList, List<AggregateNode> aggregates)	Binding this expression means setting the result DataTypeServices.
boolean	categorize(JBitSet referencedTabs, boolean simplePredsOnly)	Categorize this predicate.
(package private) void	generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)	Do code generation for coalesce/value
(package private) boolean	isEquivalent(ValueNode o)	Tests if this node is equivalent to the specified ValueNode.
(package private) ValueNode	preprocess(int numTables, FromList outerFromList, SubqueryList outerSubqueryList, PredicateList outerPredicateList)	Preprocess an expression tree.
(package private) void	printSubNodes(int depth)	Prints the sub-nodes of this object.
ValueNode	remapColumnReferencesToExpressions()	Remap all the ColumnReferences in this tree to be clones of the underlying expression.
String	toString()	Convert this object to a String.

Methods inherited from class ValueNode

bindExpression, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getOrderableVariantType, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeKind, optimizableEqualityNode, putAndsOnTop, requiresTypeFromContext, selectivity, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

Methods inherited from class QueryTreeNode

accept, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContext, getContextManager, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getLongProperty, getNullNode, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, getUDTDesc, isAtomic, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, optimizerTracingIsOn, orReliability, parseSearchCondition, parseStatement, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

functionName

String functionName

argumentsList

ValueNodeList argumentsList

firstNonParameterNodeIdx

private int firstNonParameterNodeIdx

The generated method will generate code to call coalesce on this non-parameter argument.

Constructor Details

CoalesceFunctionNode

CoalesceFunctionNode(String functionName,
 ValueNodeList argumentsList,
 ContextManager cm)

Constructor for a CoalesceFunctionNode

Parameters:

functionName - Tells if the function was called with name COALESCE or with name VALUE

argumentsList - The list of arguments to the coalesce/value function

cm - The context manager

Method Details

bindExpression

ValueNode bindExpression(FromList fromList,
 SubqueryList subqueryList,
 List<AggregateNode> aggregates)
                  throws StandardException

Binding this expression means setting the result DataTypeServices. In this case, the result type is based on the rules in the table listed earlier.

Overrides:

bindExpression in class ValueNode

Parameters:

fromList - The FROM list for the statement.

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

generateExpression

void generateExpression(ExpressionClassBuilder acb,
 MethodBuilder mb)
                 throws StandardException

Do code generation for coalesce/value

Overrides:

generateExpression in class ValueNode

Parameters:

acb - The ExpressionClassBuilder for the class we're generating

mb - The method the expression will go into

Throws:

StandardException - Thrown on error

toString

public String toString()

Description copied from class: ValueNode

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

isEquivalent

boolean isEquivalent(ValueNode o)
              throws StandardException

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

acceptChildren

void acceptChildren(Visitor v)
             throws StandardException

Accept the visitor for all visitable children of this node.

Overrides:

acceptChildren in class QueryTreeNode

Parameters:

v - the visitor

Throws:

StandardException - on error in the visitor

categorize

public boolean categorize(JBitSet referencedTabs,
 boolean simplePredsOnly)
                   throws StandardException

Categorize this predicate.

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.

Throws:

StandardException - Thrown on error

See Also:

• ValueNode.categorize(JBitSet, boolean)

preprocess

ValueNode preprocess(int numTables,
 FromList outerFromList,
 SubqueryList outerSubqueryList,
 PredicateList outerPredicateList)
              throws StandardException

Preprocess an expression tree. We do a number of transformations here (including subqueries, IN lists, LIKE and BETWEEN) plus subquery flattening. NOTE: This is done before the outer ResultSetNode is preprocessed.

Overrides:

preprocess in class ValueNode

Parameters:

numTables - Number of tables in the DML Statement

outerFromList - FromList from outer query block

outerSubqueryList - SubqueryList from outer query block

outerPredicateList - PredicateList from outer query block

Returns:

The modified expression

Throws:

StandardException - Thrown on error

remapColumnReferencesToExpressions

public ValueNode remapColumnReferencesToExpressions()
                                             throws StandardException

Remap all the ColumnReferences in this tree to be clones of the underlying expression.

Overrides:

remapColumnReferencesToExpressions in class ValueNode

Returns:

the remapped tree

Throws:

StandardException - if an error occurs