org.apache.derby.impl.sql.compile

Class FromList

java.lang.Object

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

org.apache.derby.impl.sql.compile.QueryTreeNodeVector<ResultSetNode>

org.apache.derby.impl.sql.compile.FromList

All Implemented Interfaces:

java.lang.Iterable<ResultSetNode>, OptimizableList, Visitable

class FromList
extends QueryTreeNodeVector<ResultSetNode>
implements OptimizableList

A FromList represents the list of tables in a FROM clause in a DML statement. It extends QueryTreeNodeVector.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) boolean	fixedJoinOrder
private boolean	isTransparent
(package private) java.util.Properties	properties
private boolean	referencesSessionSchema
(package private) boolean	useStatistics
private WindowList	windows Window definitions used for resolving window functions not containing in-line window specifications, but referring window definitions

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNodeVector

eltClass

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Constructor Summary

Constructors

Constructor and Description
FromList(boolean optimizeJoinOrder, ContextManager cm) Constructor for a FromList
FromList(boolean optimizeJoinOrder, FromTable fromTable, ContextManager cm) Constructor for a FromList
FromList(ContextManager cm) Does not change the default for join order optimization, i.e.

Method Summary

Modifier and Type	Method and Description
(package private) void	addFromTable(FromTable fromTable) Add a table to the FROM list.
(package private) ResultColumn	bindColumnReference(ColumnReference columnReference) Bind a column reference to one of the tables in this FromList.
(package private) void	bindExpressions(FromList fromListParam) Bind the expressions in this FromList.
(package private) void	bindResultColumns(FromList fromListParam) Bind the result columns of the ResultSetNodes in this FromList when there is no base table to bind them to.
(package private) void	bindTables(DataDictionary dataDictionary, FromList fromListParam)
(package private) void	bindUntypedNullsToResultColumns(ResultColumnList bindingRCL) Bind any untyped null nodes to the types in the given ResultColumnList.
private void	constructorMinion(boolean optimizeJoinOrder)
(package private) void	decrementLevel(int decrement) Decrement (query block) level (0-based) for all of the tables in this from list.
(package private) ResultColumnList	expandAll(TableName allTableName) Expand a "*" into the appropriate ResultColumnList.
(package private) void	flattenFromTables(ResultColumnList rcl, PredicateList predicateList, SubqueryList sql, GroupByList gbl, ValueNode havingClause) Flatten all the FromTables that are flattenable.
(package private) void	genExistsBaseTables(JBitSet referencedTableMap, FromList outerFromList, boolean isNotExists) Mark all of the FromBaseTables in the list as EXISTS FBTs.
(package private) FromTable	getFromTableByName(java.lang.String name, java.lang.String schemaName, boolean exactMatch) Determine whether or not the specified name is an exposed name in the current query block.
(package private) FromTable	getFromTableByResultColumn(ResultColumn rc) Get the FromTable from this list which has the specified ResultColumn in its RCL.
Optimizable	getOptimizable(int index) Return the nth Optimizable in the list.
(package private) int[]	getTableNumbers()
(package private) WindowList	getWindows()
(package private) boolean	hashJoinSpecified() Return whether or not the user specified a hash join for any of the tables in this list.
void	initAccessPaths(Optimizer optimizer) Init the access paths for these optimizables.
(package private) void	isJoinColumnForRightOuterJoin(ResultColumn rc) Go through the list of the tables and see if the passed ResultColumn is a join column for a right outer join with USING/NATURAL clause.
boolean	legalJoinOrder(int numTablesInQuery) Tell whether the join order is legal.
(package private) boolean	LOJ_reorderable(int numTables)
(package private) void	markAsTransparent() Indicate that this FromList is "transparent", which means that its FromTables should be bound to tables from an outer query.
boolean	optimizeJoinOrder() Tell whether the join order should be optimized.
(package private) void	preprocess(int numTables, GroupByList gbl, ValueNode predicateTree) Preprocess the query tree - this currently means: o Generating a referenced table map for each ResultSetNode.
(package private) void	pushPredicates(PredicateList predicateList) Categorize and push the predicates that are pushable.
boolean	referencesSessionSchema() Return true if the node references SESSION schema tables (temporary or permanent)
(package private) boolean	referencesTarget(java.lang.String name, boolean baseTable) Search to see if a query references the specifed table name.
(package private) void	rejectParameters() Check for (and reject) all ?
void	reOrder(int[] joinOrder) Set the join order for this list of optimizables.
(package private) boolean	returnsAtMostSingleRow(ResultColumnList rcl, ValueNode whereClause, PredicateList wherePredicates, DataDictionary dd) This method is used for both subquery flattening and distinct elimination based on a uniqueness condition.
(package private) void	setLevel(int level) Set the (query block) level (0-based) for the FromTables in this FromList.
void	setOptimizable(int index, Optimizable optimizable) Set the nth Optimizable to the specified Optimizable.
(package private) void	setProperties(java.util.Properties props) Set the Properties list for this FromList.
(package private) void	setWindows(WindowList windows) Set windows field to the supplied value.
(package private) boolean	tableNumberIsNotExists(int tableNumber) determine whether this table is NOT EXISTS.
(package private) int	updateTargetLockMode() Get the lock mode for the target of an update statement (a delete or update).
boolean	useStatistics() user can specify that s/he doesn't want statistics to be considered when optimizing the query.
void	verifyProperties(DataDictionary dDictionary) Verify that the Properties list with optimizer overrides, if specified, is valid

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNodeVector

acceptChildren, addElement, destructiveAppend, elementAt, indexOf, insertElementAt, iterator, nondestructiveAppend, printSubNodes, removeAllElements, removeElement, removeElementAt, setElementAt, size

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

accept, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generate, 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, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, toString, treePrint, treePrint, verifyClassExist

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.derby.iapi.sql.compile.OptimizableList

size

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

properties

java.util.Properties properties

fixedJoinOrder

boolean fixedJoinOrder

useStatistics

boolean useStatistics

referencesSessionSchema

private boolean referencesSessionSchema

isTransparent

private boolean isTransparent

windows

private WindowList windows

Window definitions used for resolving window functions not containing in-line window specifications, but referring window definitions

Constructor Detail

FromList

FromList(ContextManager cm)

Does not change the default for join order optimization, i.e. false.

Parameters:

cm - context manager

FromList

FromList(boolean optimizeJoinOrder,
         ContextManager cm)

Constructor for a FromList

Parameters:

optimizeJoinOrder - true if join order optimization is to be performed

cm - context manager

FromList

FromList(boolean optimizeJoinOrder,
         FromTable fromTable,
         ContextManager cm)
  throws StandardException

Constructor for a FromList

Parameters:

optimizeJoinOrder - true if join order optimization is to be performed

fromTable - initialize list with this table

cm - context manager

Throws:

StandardException - Thrown on error

Method Detail

constructorMinion

private void constructorMinion(boolean optimizeJoinOrder)

getOptimizable

public Optimizable getOptimizable(int index)

Description copied from interface: OptimizableList

Return the nth Optimizable in the list.

Specified by:

getOptimizable in interface OptimizableList

Parameters:

index - "index" (0 based) into the list.

Returns:

Optimizable The nth Optimizables in the list.

See Also:

OptimizableList.getOptimizable(int)

setOptimizable

public void setOptimizable(int index,
                           Optimizable optimizable)

Description copied from interface: OptimizableList

Set the nth Optimizable to the specified Optimizable.

Specified by:

setOptimizable in interface OptimizableList

Parameters:

index - "index" (0 based) into the list.

optimizable - New nth Optimizable.

See Also:

OptimizableList.setOptimizable(int, org.apache.derby.iapi.sql.compile.Optimizable)

verifyProperties

public void verifyProperties(DataDictionary dDictionary)
                      throws StandardException

Description copied from interface: OptimizableList

Verify that the Properties list with optimizer overrides, if specified, is valid

Specified by:

verifyProperties in interface OptimizableList

Parameters:

dDictionary - The DataDictionary to use.

Throws:

StandardException - Thrown on error

See Also:

OptimizableList.verifyProperties(org.apache.derby.iapi.sql.dictionary.DataDictionary)

addFromTable

final void addFromTable(FromTable fromTable)
                 throws StandardException

Add a table to the FROM list.

Parameters:

fromTable - A FromTable to add to the list

Throws:

StandardException - Thrown on error

referencesTarget

boolean referencesTarget(java.lang.String name,
                         boolean baseTable)
                  throws StandardException

Search to see if a query references the specifed table name.

Parameters:

name - Table name (String) to search for.

baseTable - Whether or not name is for a base table

Returns:

true if found, else false

Throws:

StandardException - Thrown on error

referencesSessionSchema

public boolean referencesSessionSchema()
                                throws StandardException

Return true if the node references SESSION schema tables (temporary or permanent)

Overrides:

referencesSessionSchema in class QueryTreeNode

Returns:

true if references SESSION schema tables, else false

Throws:

StandardException - Thrown on error

getFromTableByName

FromTable getFromTableByName(java.lang.String name,
                             java.lang.String schemaName,
                             boolean exactMatch)
                      throws StandardException

Determine whether or not the specified name is an exposed name in the current query block.

Parameters:

name - The specified name to search for as an exposed name.

schemaName - Schema name, if non-null.

exactMatch - Whether or not we need an exact match on specified schema and table names or match on table id.

Returns:

The FromTable, if any, with the exposed name.

Throws:

StandardException - Thrown on error

isJoinColumnForRightOuterJoin

void isJoinColumnForRightOuterJoin(ResultColumn rc)

Go through the list of the tables and see if the passed ResultColumn is a join column for a right outer join with USING/NATURAL clause.

See Also:

HalfOuterJoinNode.isJoinColumnForRightOuterJoin(org.apache.derby.impl.sql.compile.ResultColumn)

bindTables

void bindTables(DataDictionary dataDictionary,
                FromList fromListParam)
         throws StandardException

Throws:

StandardException

bindExpressions

void bindExpressions(FromList fromListParam)
              throws StandardException

Bind the expressions in this FromList. This means binding the sub-expressions, as well as figuring out what the return type is for each expression.

Throws:

StandardException - Thrown on error

bindResultColumns

void bindResultColumns(FromList fromListParam)
                throws StandardException

Bind the result columns of the ResultSetNodes in this FromList when there is no base table to bind them to. This is useful for SELECT statements, where the result columns get their types from the expressions that live under them.

Parameters:

fromListParam - FromList to use/append to.

Throws:

StandardException - Thrown on error

expandAll

ResultColumnList expandAll(TableName allTableName)
                    throws StandardException

Expand a "*" into the appropriate ResultColumnList. If the "*" is unqualified it will expand into a list of all columns in all of the base tables in the from list at the current nesting level; otherwise it will expand into a list of all of the columns in the base table that matches the qualification. NOTE: Callers are responsible for ordering the FromList by nesting level, with tables at the deepest (current) nesting level first. We will expand the "*" into a list of all columns from all tables having the same nesting level as the first FromTable in this list. The check for nesting level exists because it's possible that this FromList includes FromTables from an outer query, which can happen if there is a "transparent" FromList above this one in the query tree. Ex: select j from onerow where exists (select 1 from somerow union select * from diffrow where onerow.j < diffrow.k) If "this" is the FromList for the right child of the UNION then it will contain both "diffrow" and "onerow", the latter of which was passed down via a transparent FromList (to allow binding of the WHERE clause). In that case the "*" should only expand the result columns of "diffrow"; it should not expand the result columns of "onerow" because that table is from an outer query. We can achieve this selective expansion by looking at nesting levels.

Parameters:

allTableName - The qualification on the "*" as a String.

Returns:

ResultColumnList representing expansion

Throws:

StandardException - Thrown on error

bindColumnReference

ResultColumn bindColumnReference(ColumnReference columnReference)
                          throws StandardException

Bind a column reference to one of the tables in this FromList. The column name must be unique within the tables in the FromList. An exception is thrown if a column name is not unique. This method fills in various fields in the column reference.

NOTE: Callers are responsible for ordering the FromList by nesting level, with tables at the deepest (current) nesting level first. We will try to match against all FromTables at a given nesting level. If no match is found at a nesting level, then we proceed to the next level. We stop walking the list when the nesting level changes and we have found a match.

NOTE: If the ColumnReference is qualified, then we will stop the search at the first nesting level where there is a match on the exposed table name. For example,

s (a, b, c), t (d, e, f)
                select * from s where exists (select * from t s where s.c = a)
 

will not find a match for s.c, which is the expected ANSI behavior.

bindTables() must have already been called on this FromList before calling this method.

Parameters:

columnReference - The ColumnReference describing the column to bind

Returns:

ResultColumn The matching ResultColumn, or null if there is no matching column

Throws:

StandardException - Thrown on error

rejectParameters

void rejectParameters()
               throws StandardException

Check for (and reject) all ? parameters directly under the ResultColumns. This is done for SELECT statements.

Throws:

StandardException - Thrown if a ? parameter found directly under a ResultColumn

LOJ_reorderable

boolean LOJ_reorderable(int numTables)
                 throws StandardException

Throws:

StandardException

preprocess

void preprocess(int numTables,
                GroupByList gbl,
                ValueNode predicateTree)
         throws StandardException

Preprocess the query tree - this currently means: o Generating a referenced table map for each ResultSetNode. o Putting the WHERE and HAVING clauses in conjunctive normal form (CNF). o Converting the WHERE and HAVING clauses into PredicateLists and classifying them. o Flatten those FromSubqueries which can be flattened. o Ensuring that a ProjectRestrictNode is generated on top of every FromBaseTable and generated in place of every FromSubquery which could not be flattened. o Pushing single table predicates down to the new ProjectRestrictNodes.

Parameters:

numTables - The number of tables in the DML Statement

gbl - The group by list, if any

Throws:

StandardException - Thrown on error

flattenFromTables

void flattenFromTables(ResultColumnList rcl,
                       PredicateList predicateList,
                       SubqueryList sql,
                       GroupByList gbl,
                       ValueNode havingClause)
                throws StandardException

Flatten all the FromTables that are flattenable. RESOLVE - right now we just flatten FromSubqueries. We should also flatten flattenable JoinNodes here.

Parameters:

rcl - The RCL from the outer query

predicateList - The PredicateList from the outer query

sql - The SubqueryList from the outer query

gbl - The group by list, if any

havingClause - The HAVING clause, if any

Throws:

StandardException - Thrown on error

pushPredicates

void pushPredicates(PredicateList predicateList)
             throws StandardException

Categorize and push the predicates that are pushable.

Parameters:

predicateList - The query's PredicateList

Throws:

StandardException - Thrown on error

setLevel

void setLevel(int level)

Set the (query block) level (0-based) for the FromTables in this FromList.

Parameters:

level - The query block level for this table.

getFromTableByResultColumn

FromTable getFromTableByResultColumn(ResultColumn rc)

Get the FromTable from this list which has the specified ResultColumn in its RCL.

Parameters:

rc - The ResultColumn match on.

Returns:

FromTable The matching FromTable.

setProperties

void setProperties(java.util.Properties props)
            throws StandardException

Set the Properties list for this FromList.

Throws:

StandardException - Thrown on error

reOrder

public void reOrder(int[] joinOrder)

Description copied from interface: OptimizableList

Set the join order for this list of optimizables. The join order is represented as an array of integers - each entry in the array stands for the order of the corresponding element in the list. For example, a joinOrder of {2, 0, 1} means that the 3rd Optimizable in the list (element 2, since we are zero-based) is the first one in the join order, followed by the 1st element in the list, and finally by the 2nd element in the list. This method shuffles this OptimizableList to match the join order. Obviously, the size of the array must equal the number of elements in the array, and the values in the array must be between 0 and the number of elements in the array minus 1, and the values in the array must be unique.

Specified by:

reOrder in interface OptimizableList

See Also:

OptimizableList.reOrder(int[])

useStatistics

public boolean useStatistics()

Description copied from interface: OptimizableList

user can specify that s/he doesn't want statistics to be considered when optimizing the query.

Specified by:

useStatistics in interface OptimizableList

See Also:

OptimizableList.useStatistics()

optimizeJoinOrder

public boolean optimizeJoinOrder()

Description copied from interface: OptimizableList

Tell whether the join order should be optimized.

Specified by:

optimizeJoinOrder in interface OptimizableList

See Also:

OptimizableList.optimizeJoinOrder()

legalJoinOrder

public boolean legalJoinOrder(int numTablesInQuery)

Description copied from interface: OptimizableList

Tell whether the join order is legal.

Specified by:

legalJoinOrder in interface OptimizableList

See Also:

OptimizableList.legalJoinOrder(int)

initAccessPaths

public void initAccessPaths(Optimizer optimizer)

Description copied from interface: OptimizableList

Init the access paths for these optimizables.

Specified by:

initAccessPaths in interface OptimizableList

Parameters:

optimizer - The optimizer being used.

See Also:

OptimizableList.initAccessPaths(org.apache.derby.iapi.sql.compile.Optimizer)

bindUntypedNullsToResultColumns

void bindUntypedNullsToResultColumns(ResultColumnList bindingRCL)
                              throws StandardException

Bind any untyped null nodes to the types in the given ResultColumnList.

Parameters:

bindingRCL - The ResultColumnList with the types to bind to.

Throws:

StandardException - Thrown on error

decrementLevel

void decrementLevel(int decrement)

Decrement (query block) level (0-based) for all of the tables in this from list. This is useful when flattening a subquery.

Parameters:

decrement - The amount to decrement by.

returnsAtMostSingleRow

boolean returnsAtMostSingleRow(ResultColumnList rcl,
                               ValueNode whereClause,
                               PredicateList wherePredicates,
                               DataDictionary dd)
                        throws StandardException

This method is used for both subquery flattening and distinct elimination based on a uniqueness condition. For subquery flattening we want to make sure that the query block will return at most 1 row. For distinct elimination we want to make sure that the query block will not return any duplicates. This is true if every table in the from list is (a base table and the set of columns from the table that are in equality comparisons with expressions that do not include columns from the same table is a superset of any unique index on the table) or an EXISTS FBT. In addition, at least 1 of the tables in the list has a set of columns in equality comparisons with expressions that do not include column references from the same query block is a superset of a unique index on that table. (This ensures that the query block will onlyr return a single row.) This method is expected to be called after normalization and after the from list has been preprocessed. It can be called both before and after the predicates have been pulled from the where clause. The algorithm for this is as follows If any table in the query block is not a base table, give up. For each table in the query Ignore exists table since they can only produce one row create a matrix of tables and columns from the table (tableColMap) (this is used to keep track of the join columns and constants that can be used to figure out whether the rows from a join or in a select list are distinct based on unique indexes) create an array of columns from the table(eqOuterCol) (this is used to determine that only one row will be returned from a join) if the current table is the table for the result columns set the result columns in the eqOuterCol and tableColMap (if these columns are a superset of a unique index and all joining tables result in only one row, the results will be distinct) go through all the predicates and update tableColMap and eqOuterCol with join columns and correlation variables, parameters and constants since setting constants, correlation variables and parameters, reduces the number of columns required for uniqueness in a multi-column index, they are set for all the tables (if the table is not the result table, in this case only the column of the result table is set) join columns are just updated for the column in the row of the joining table. check if the marked columns in tableColMap are a superset of a unique index (This means that the join will only produce 1 row when joined with 1 row of another table) check that there is a least one table for which the columns in eqOuterCol(i.e. constant values) are a superset of a unique index (This quarantees that there will be only one row selected from this table). Once all tables have been evaluated, check that all the tables can be joined by unique index or will have only one row

Parameters:

rcl - If non-null, the RCL from the query block. If non-null for subqueries, then entry can be considered as part of an = comparison.

whereClause - The WHERE clause to consider.

wherePredicates - The predicates that have already been pulled from the WHERE clause.

dd - The DataDictionary to use.

Returns:

Whether or not query block will return at most 1 row for a subquery, no duplicates for a distinct.

Throws:

StandardException - Thrown on error

getTableNumbers

int[] getTableNumbers()

genExistsBaseTables

void genExistsBaseTables(JBitSet referencedTableMap,
                         FromList outerFromList,
                         boolean isNotExists)
                  throws StandardException

Mark all of the FromBaseTables in the list as EXISTS FBTs. Each EBT has the same dependency list - those tables that are referenced minus the tables in the from list.

Parameters:

referencedTableMap - The referenced table map.

outerFromList - FromList from outer query block

isNotExists - Whether or not for NOT EXISTS

Throws:

StandardException - Thrown on error

tableNumberIsNotExists

boolean tableNumberIsNotExists(int tableNumber)
                        throws StandardException

determine whether this table is NOT EXISTS. This routine searches for the indicated table number in the fromlist and returns TRUE if the table is present in the from list and is marked NOT EXISTS, false otherwise. A table may be present in the from list for NOT EXISTS if it is used as a correlated NOT EXISTS subquery. In such a situation, when the subquery is flattened, it is important that we remember that this is a NOT EXISTS subquery, because the join semantics are different (we're looking for rows that do NOT match, rather than rows that do). And since the join semantics are different, we cannot include this table into a transitive closure of equijoins (See DERBY-3033 for a situation where this occurs).

Parameters:

tableNumber - which table to check

Returns:

true if this table is in the from list as NOT EXISTS

Throws:

StandardException

updateTargetLockMode

int updateTargetLockMode()

Get the lock mode for the target of an update statement (a delete or update). The update mode will always be row for CurrentOfNodes. It will be table if there is no where clause.

Returns:

The lock mode

hashJoinSpecified

boolean hashJoinSpecified()

Return whether or not the user specified a hash join for any of the tables in this list.

Returns:

Whether or not the user specified a hash join for any of the tables in this list.

markAsTransparent

void markAsTransparent()

Indicate that this FromList is "transparent", which means that its FromTables should be bound to tables from an outer query. Generally this is not allowed, but there are exceptions. See SetOperatorNode.setResultToBooleanTrueNode() for more.

setWindows

void setWindows(WindowList windows)

Set windows field to the supplied value.

Parameters:

windows - list of window definitions associated with a SELECT.

getWindows

WindowList getWindows()

Returns:

list of window definitions associated with a SELECT.