net.sf.saffron.sql2rel
Class SqlToRelConverter

java.lang.Object
  |
  +--net.sf.saffron.sql2rel.SqlToRelConverter

public class SqlToRelConverter

extends Object

Converts a SQL parse tree (consisting of SqlNode objects) into a relational algebra expression (consisting of SaffronRel objects).

This class accomplishes in one step what you could accomplish in two steps using a SqlToOpenjavaConverter followed by a OJQueryExpander.

Since:

Oct 10, 2003

Version:

$Id: //open/saffron/src/net/sf/saffron/sql2rel/SqlToRelConverter.java#12 $

Author:

jhyde

Nested Class Summary

private class	SqlToRelConverter.Blackboard Workspace for translating an individual SELECT statement (or sub-SELECT).
(package private) static class	SqlToRelConverter.DeferredLookup Contains the information necessary to repeat a call to Blackboard#lookup.
(package private) class	SqlToRelConverter.NullDefaultValueFactory An implementation of DefaultValueFactory which always supplies NULL.
static class	SqlToRelConverter.SchemaCatalogReader A SchemaCatalogReader looks up catalog information from a saffron schema object.

Field Summary

private static HashMap	binaryMap Maps an operator name to an operator.
private VolcanoCluster	cluster
private SaffronConnection	connection
private DefaultValueFactory	defaultValueFactory
private static HashMap	functionMap Maps a function name to an operator.
(package private) ArrayList	leaves
private HashMap	mapScopeToRel
private static HashMap	postfixMap Maps an operator name to an operator.
private static HashMap	prefixMap Maps an operator name to an operator.
private boolean	producingFlatReferences
private RexBuilder	rexBuilder
private SaffronSchema	schema
private SqlValidator	validator

Constructor Summary

SqlToRelConverter(SqlValidator validator, SaffronSchema schema, Environment env, SaffronConnection connection)
Creates a converter

Method Summary

private static boolean	contains(String[] names, int length, String s)
private SaffronRel	convertDelete(SqlDelete call)
private SaffronRel	convertExists(SqlToRelConverter.Blackboard bb, SqlNode seek, SqlNode condition, RexLiteral extraExpr, String extraName) Converts a query into a join with an indicator variable.
RexNode	convertExpression(SqlToRelConverter.Blackboard bb, SqlNode node) Converts an expression from SqlNode to RexNode format.
private RexNode[]	convertExpressionList(SqlToRelConverter.Blackboard bb, SqlNode[] nodes)
private void	convertFrom(SqlToRelConverter.Blackboard bb, SqlNode from) Converts a FROM clause into a relational expression.
private void	convertGroup(SqlToRelConverter.Blackboard bb, SqlNodeList groupList) Converts a GROUP BY clause.
private void	convertHaving(SqlToRelConverter.Blackboard bb, SqlNode having)
private RexNode	convertIdentifier(SqlToRelConverter.Blackboard bb, SqlIdentifier identifier) Converts an identifier into an expression in a given scope.
private SaffronRel	convertInsert(SqlInsert call)
private RexNode	convertJoinCondition(SqlToRelConverter.Blackboard bb, SqlNode condition, SqlJoinOperator.ConditionType conditionType, SaffronRel leftRel, SaffronRel rightRel)
private static int	convertJoinType(SqlJoinOperator.JoinType joinType)
private RexLiteral	convertLiteral(SqlLiteral literal)
private void	convertOrder(SqlToRelConverter.Blackboard bb, SqlNodeList orderList) Converts an ORDER BY clause.
SaffronRel	convertQuery(SqlNode query) Converts a query's parse tree into a relational expression.
private SaffronRel	convertQueryOrInList(SqlToRelConverter.Blackboard bb, SqlNode seek)
private SaffronRel	convertQueryRecursive(SqlNode query)
private SaffronRel	convertRowConstructor(SqlToRelConverter.Blackboard bb, SqlCall rowConstructor) Converts a row constructor into a relational expression.
SaffronRel	convertSelect(SqlSelect query) Converts a SELECT statement's parse tree into a relational expression.
private void	convertSelectList(SqlToRelConverter.Blackboard bb, SqlNodeList selectList)
private void	convertValues(SqlToRelConverter.Blackboard bb, SqlCall values) Converts a values clause (as in "INSERT INTO T(x,y) VALUES (1,2)") into a relational expression.
private void	convertWhere(SqlToRelConverter.Blackboard bb, SqlNode where)
static HashMap	createBinaryMap()
(package private) VolcanoCluster	createCluster(Environment env)
static HashMap	createFunctionMap()
private JoinRel	createJoin(SqlToRelConverter.Blackboard bb, SaffronRel leftRel, SaffronRel rightRel, SqlNode condition, SqlJoinOperator.ConditionType conditionType, int joinType)
static HashMap	createPostfixMap()
static HashMap	createPrefixMap()
private void	findSubqueries(SqlToRelConverter.Blackboard bb, SqlNode node) Builds a list of all IN or EXISTS operators inside SQL parse tree.
RexBuilder	getRexBuilder() Returns the row-expression builder.
static SaffronTable	getSaffronTable(SqlValidator.Scope scope, SaffronSchema schema) Converts a scope into a SaffronTable.
private boolean	isRowConstructor(SqlNode node)
private static RexKind	mapSqlFunToRex(SqlFunction op)
private void	replaceSubqueries(SqlToRelConverter.Blackboard bb, SqlNode expr)
void	requestFlatReferences() Request that references to join outputs be produced as "flat" FieldAccesses rather than preserving the structure of the join.
void	setDefaultValueFactory(DefaultValueFactory factory) Set a new DefaultValueFactory.
private void	substituteSubqueries(SqlToRelConverter.Blackboard bb)
static Test	suite() Standard method recognised by JUnit.
private static String	uniqueFieldName(String[] names, int length, String s) Generates a unique name

Methods inherited from class java.lang.Object

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

Field Detail

binaryMap

private static final HashMap binaryMap

Maps an operator name to an operator. For example, binaryMap.get("/") yields RexKind.Divide.

prefixMap

private static final HashMap prefixMap

Maps an operator name to an operator. For example, binaryMap.get("-") yields RexKind.MinusPrefix.

postfixMap

private static final HashMap postfixMap

Maps an operator name to an operator.

functionMap

private static final HashMap functionMap

Maps a function name to an operator.

validator

private final SqlValidator validator

rexBuilder

private RexBuilder rexBuilder

connection

private SaffronConnection connection

schema

private SaffronSchema schema

cluster

private VolcanoCluster cluster

mapScopeToRel

private HashMap mapScopeToRel

defaultValueFactory

private DefaultValueFactory defaultValueFactory

producingFlatReferences

private boolean producingFlatReferences

leaves

final ArrayList leaves

Constructor Detail

SqlToRelConverter

public SqlToRelConverter(SqlValidator validator,
                         SaffronSchema schema,
                         Environment env,
                         SaffronConnection connection)

Creates a converter

Parameters:

validator -

schema -

env -

connection -

Pre-condition:

connection != null

Method Detail

getRexBuilder

public RexBuilder getRexBuilder()

Returns the row-expression builder.

setDefaultValueFactory

public void setDefaultValueFactory(DefaultValueFactory factory)

Set a new DefaultValueFactory. To have any effect, this must be called before any convert method.

Parameters:

factory - new DefaultValueFactory

requestFlatReferences

public void requestFlatReferences()

Request that references to join outputs be produced as "flat" FieldAccesses rather than preserving the structure of the join.

convertQuery

public SaffronRel convertQuery(SqlNode query)

Converts a query's parse tree into a relational expression.

convertSelect

public SaffronRel convertSelect(SqlSelect query)

Converts a SELECT statement's parse tree into a relational expression.

convertHaving

private void convertHaving(SqlToRelConverter.Blackboard bb,
                           SqlNode having)

convertWhere

private void convertWhere(SqlToRelConverter.Blackboard bb,
                          SqlNode where)

replaceSubqueries

private void replaceSubqueries(SqlToRelConverter.Blackboard bb,
                               SqlNode expr)

substituteSubqueries

private void substituteSubqueries(SqlToRelConverter.Blackboard bb)

convertExists

private SaffronRel convertExists(SqlToRelConverter.Blackboard bb,
                                 SqlNode seek,
                                 SqlNode condition,
                                 RexLiteral extraExpr,
                                 String extraName)

Converts a query into a join with an indicator variable. The result is a relational expression which outer joins a boolean condition column to the original query. After performing the outer join, the condition will be TRUE if the EXISTS condition holds, NULL otherwise.

Parameters:

bb -

seek - A query, for example 'select * from emp' or 'values (1,2,3)' or '('Foo', 34)'.

condition - May be null, or a node, or a node list

extraExpr - Column expression to add. "TRUE" for EXISTS and IN

extraName - Name of expression to add.

Returns:

relational expression which outer joins a boolean condition column

Pre-condition:

extraExpr == null || extraName != null

convertQueryOrInList

private SaffronRel convertQueryOrInList(SqlToRelConverter.Blackboard bb,
                                        SqlNode seek)

isRowConstructor

private boolean isRowConstructor(SqlNode node)

uniqueFieldName

private static String uniqueFieldName(String[] names,
                                      int length,
                                      String s)

Generates a unique name

Parameters:

names - Array of existing names

length - Number of existing names

s - Suggested name

Returns:

Name which does not match any of the names in the first length positions of the names array.

contains

private static boolean contains(String[] names,
                                int length,
                                String s)

findSubqueries

private void findSubqueries(SqlToRelConverter.Blackboard bb,
                            SqlNode node)

Builds a list of all IN or EXISTS operators inside SQL parse tree. Does not traverse inside queries.

suite

public static Test suite()

Standard method recognised by JUnit.

convertExpression

public RexNode convertExpression(SqlToRelConverter.Blackboard bb,
                                 SqlNode node)

Converts an expression from SqlNode to RexNode format.

Parameters:

bb - Workspace

node - Expression to translate

Returns:

Converted expression

mapSqlFunToRex

private static RexKind mapSqlFunToRex(SqlFunction op)

convertExpressionList

private RexNode[] convertExpressionList(SqlToRelConverter.Blackboard bb,
                                        SqlNode[] nodes)

convertFrom

private void convertFrom(SqlToRelConverter.Blackboard bb,
                         SqlNode from)

Converts a FROM clause into a relational expression.

Parameters:

bb - Scope within which to resolve identifiers

from - FROM clause of a query. Examples include: a single table ("SALES.EMP"), an aliased table ("EMP AS E"), a list of tables ("EMP, DEPT"), an ANSI Join expression ("EMP JOIN DEPT ON EMP.DEPTNO = DEPT.DEPTNO"), a VALUES clause ("VALUES ('Fred', 20)"), a query ("(SELECT * FROM EMP WHERE GENDER = 'F')"), or any combination of the above.

Post-condition:

return != null

createJoin

private JoinRel createJoin(SqlToRelConverter.Blackboard bb,
                           SaffronRel leftRel,
                           SaffronRel rightRel,
                           SqlNode condition,
                           SqlJoinOperator.ConditionType conditionType,
                           int joinType)

convertJoinCondition

private RexNode convertJoinCondition(SqlToRelConverter.Blackboard bb,
                                     SqlNode condition,
                                     SqlJoinOperator.ConditionType conditionType,
                                     SaffronRel leftRel,
                                     SaffronRel rightRel)

convertJoinType

private static int convertJoinType(SqlJoinOperator.JoinType joinType)

convertGroup

private void convertGroup(SqlToRelConverter.Blackboard bb,
                          SqlNodeList groupList)

Converts a GROUP BY clause.

Parameters:

bb - Scope within which to resolve identifiers

groupList - GROUP BY clause, or null

Pre-condition:

child != null

Post-condition:

return != null

convertLiteral

private RexLiteral convertLiteral(SqlLiteral literal)

convertOrder

private void convertOrder(SqlToRelConverter.Blackboard bb,
                          SqlNodeList orderList)

Converts an ORDER BY clause.

Parameters:

bb - Scope within which to resolve identifiers

orderList - Order by clause, or null

Pre-condition:

bb.root != null

Post-condition:

return != null

convertQueryRecursive

private SaffronRel convertQueryRecursive(SqlNode query)

convertInsert

private SaffronRel convertInsert(SqlInsert call)

convertDelete

private SaffronRel convertDelete(SqlDelete call)

convertIdentifier

private RexNode convertIdentifier(SqlToRelConverter.Blackboard bb,
                                  SqlIdentifier identifier)

Converts an identifier into an expression in a given scope. For example, the "empno" in "select empno from emp join dept" becomes "emp.empno".

convertRowConstructor

private SaffronRel convertRowConstructor(SqlToRelConverter.Blackboard bb,
                                         SqlCall rowConstructor)

Converts a row constructor into a relational expression.

Parameters:

bb -

rowConstructor -

Returns:

Relational expression which returns a single row.

Pre-condition:

rowConstructor, isRowConstructor(rowConstructor)

convertSelectList

private void convertSelectList(SqlToRelConverter.Blackboard bb,
                               SqlNodeList selectList)

convertValues

private void convertValues(SqlToRelConverter.Blackboard bb,
                           SqlCall values)

Converts a values clause (as in "INSERT INTO T(x,y) VALUES (1,2)") into a relational expression.

createCluster

VolcanoCluster createCluster(Environment env)

createBinaryMap

public static HashMap createBinaryMap()

createPrefixMap

public static HashMap createPrefixMap()

createPostfixMap

public static HashMap createPostfixMap()

createFunctionMap

public static HashMap createFunctionMap()

getSaffronTable

public static SaffronTable getSaffronTable(SqlValidator.Scope scope,
                                           SaffronSchema schema)

Converts a scope into a SaffronTable. This is only possible if the scope represents an identifier, such as "sales.emp". Otherwise, returns null.