com.metamatrix.query.rewriter
Class QueryRewriter

java.lang.Object
  com.metamatrix.query.rewriter.QueryRewriter

public class QueryRewriter
extends java.lang.Object

Rewrites commands and command fragments to a form that is better for planning and execution. There is a current limitation that command objects themselves cannot change type, since the same object is always used.

Field Summary

static CompareCriteria	FALSE_CRITERIA
static CompareCriteria	TRUE_CRITERIA
static CompareCriteria	UNKNOWN_CRITERIA

Method Summary

static java.lang.String	convertString(java.lang.String string)
static Query	createInlineViewQuery(GroupSymbol group, QueryCommand nested, QueryMetadataInterface metadata, java.util.List actualSymbols)
static boolean	isNull(Expression expr)
static void	makeSelectUnique(Query query, boolean expressionSymbolsOnly)
static Criteria	optimizeCriteria(CompoundCriteria criteria) Performs simple expression flattening
static Command	rewrite(Command command, Command procCommand, QueryMetadataInterface metadata, CommandContext context)
static Criteria	rewriteCriteria(Criteria criteria, Command procCommand, CommandContext context, QueryMetadataInterface metadata) Rewrite the criteria by evaluating some trivial cases.
static Expression	rewriteExpression(Expression expression, Command procCommand, CommandContext context, QueryMetadataInterface metadata)
static void	rewriteOrderBy(QueryCommand query, Command procCommand, QueryMetadataInterface metadata, CommandContext context) Rewrite the order by clause.

Methods inherited from class java.lang.Object

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

Field Detail

TRUE_CRITERIA

public static final CompareCriteria TRUE_CRITERIA

FALSE_CRITERIA

public static final CompareCriteria FALSE_CRITERIA

UNKNOWN_CRITERIA

public static final CompareCriteria UNKNOWN_CRITERIA

Method Detail

rewrite

public static Command rewrite(Command command,
                              Command procCommand,
                              QueryMetadataInterface metadata,
                              CommandContext context)
                       throws QueryValidatorException

Throws:

QueryValidatorException

rewriteOrderBy

public static void rewriteOrderBy(QueryCommand query,
                                  Command procCommand,
                                  QueryMetadataInterface metadata,
                                  CommandContext context)
                           throws QueryValidatorException

Rewrite the order by clause.

Parameters:

query -

Throws:

QueryValidatorException

rewriteCriteria

public static Criteria rewriteCriteria(Criteria criteria,
                                       Command procCommand,
                                       CommandContext context,
                                       QueryMetadataInterface metadata)
                                throws QueryValidatorException

Rewrite the criteria by evaluating some trivial cases.

Parameters:

criteria - The criteria to rewrite

metadata -

userCriteria - The criteria on user's command, used in rewriting HasCriteria in the procedural language.

Returns:

The re-written criteria

Throws:

QueryValidatorException

optimizeCriteria

public static Criteria optimizeCriteria(CompoundCriteria criteria)

Performs simple expression flattening

Parameters:

criteria -

Returns:

isNull

public static boolean isNull(Expression expr)

rewriteExpression

public static Expression rewriteExpression(Expression expression,
                                           Command procCommand,
                                           CommandContext context,
                                           QueryMetadataInterface metadata)
                                    throws QueryValidatorException

Throws:

QueryValidatorException

convertString

public static java.lang.String convertString(java.lang.String string)

createInlineViewQuery

public static Query createInlineViewQuery(GroupSymbol group,
                                          QueryCommand nested,
                                          QueryMetadataInterface metadata,
                                          java.util.List actualSymbols)
                                   throws QueryMetadataException,
                                          QueryResolverException,
                                          MetaMatrixComponentException

Throws:

QueryMetadataException

QueryResolverException

MetaMatrixComponentException

makeSelectUnique

public static void makeSelectUnique(Query query,
                                    boolean expressionSymbolsOnly)