org.teiid.query.rewriter
Class QueryRewriter

java.lang.Object
  org.teiid.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 Query	createInlineViewQuery(GroupSymbol group, Command nested, QueryMetadataInterface metadata, java.util.List<SingleElementSymbol> actualSymbols)
static Command	evaluateAndRewrite(Command command, Evaluator eval, CommandContext context, QueryMetadataInterface metadata)
static boolean	isDistinctWithGroupBy(Query query)
static boolean	isNull(Expression expr)
static void	makeSelectUnique(Select select, boolean expressionSymbolsOnly)
static Criteria	optimizeCriteria(CompoundCriteria criteria, QueryMetadataInterface metadata) Performs simple expression flattening
static Command	rewrite(Command command, CreateUpdateProcedureCommand procCommand, QueryMetadataInterface metadata, CommandContext context, java.util.Map variableValues, int commandType)
static Command	rewrite(Command command, QueryMetadataInterface metadata, CommandContext context)
static Criteria	rewriteCriteria(Criteria criteria, CreateUpdateProcedureCommand procCommand, CommandContext context, QueryMetadataInterface metadata) Rewrite the criteria by evaluating some trivial cases.
static Expression	rewriteExpression(Expression expression, CreateUpdateProcedureCommand procCommand, CommandContext context, QueryMetadataInterface metadata)
QueryCommand	rewriteOrderBy(QueryCommand queryCommand) Rewrite the order by clause.
static boolean	rewriteOrderBy(QueryCommand queryCommand, OrderBy orderBy, java.util.List projectedSymbols, java.util.LinkedList<OrderByItem> unrelatedItems)

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

evaluateAndRewrite

public static Command evaluateAndRewrite(Command command,
                                         Evaluator eval,
                                         CommandContext context,
                                         QueryMetadataInterface metadata)
                                  throws TeiidProcessingException,
                                         TeiidComponentException

Throws:

TeiidProcessingException

TeiidComponentException

rewrite

public static Command rewrite(Command command,
                              CreateUpdateProcedureCommand procCommand,
                              QueryMetadataInterface metadata,
                              CommandContext context,
                              java.util.Map variableValues,
                              int commandType)
                       throws TeiidComponentException,
                              TeiidProcessingException

Throws:

TeiidComponentException

TeiidProcessingException

rewrite

public static Command rewrite(Command command,
                              QueryMetadataInterface metadata,
                              CommandContext context)
                       throws TeiidComponentException,
                              TeiidProcessingException

Throws:

TeiidComponentException

TeiidProcessingException

isDistinctWithGroupBy

public static boolean isDistinctWithGroupBy(Query query)

rewriteOrderBy

public QueryCommand rewriteOrderBy(QueryCommand queryCommand)
                            throws TeiidComponentException

Rewrite the order by clause. Unrelated order by expressions will cause the creation of nested inline views.

Parameters:

query -

Throws:

TeiidComponentException, - MetaMatrixProcessingException

TeiidComponentException

rewriteOrderBy

public static boolean rewriteOrderBy(QueryCommand queryCommand,
                                     OrderBy orderBy,
                                     java.util.List projectedSymbols,
                                     java.util.LinkedList<OrderByItem> unrelatedItems)

rewriteCriteria

public static Criteria rewriteCriteria(Criteria criteria,
                                       CreateUpdateProcedureCommand procCommand,
                                       CommandContext context,
                                       QueryMetadataInterface metadata)
                                throws TeiidComponentException,
                                       TeiidProcessingException

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:

TeiidComponentException

TeiidProcessingException

optimizeCriteria

public static Criteria optimizeCriteria(CompoundCriteria criteria,
                                        QueryMetadataInterface metadata)

Performs simple expression flattening

Parameters:

criteria -

Returns:

isNull

public static boolean isNull(Expression expr)

rewriteExpression

public static Expression rewriteExpression(Expression expression,
                                           CreateUpdateProcedureCommand procCommand,
                                           CommandContext context,
                                           QueryMetadataInterface metadata)
                                    throws TeiidComponentException,
                                           TeiidProcessingException

Throws:

TeiidComponentException

TeiidProcessingException

createInlineViewQuery

public static Query createInlineViewQuery(GroupSymbol group,
                                          Command nested,
                                          QueryMetadataInterface metadata,
                                          java.util.List<SingleElementSymbol> actualSymbols)
                                   throws QueryMetadataException,
                                          QueryResolverException,
                                          TeiidComponentException

Throws:

QueryMetadataException

QueryResolverException

TeiidComponentException

makeSelectUnique

public static void makeSelectUnique(Select select,
                                    boolean expressionSymbolsOnly)