Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.sql.compile.CursorNode

Field Summary

Modifier and Type	Field and Description
private boolean	checkIndexStats
private ValueNode	fetchFirst
private boolean	forMergeStatement
private boolean	hasJDBClimitClause
private int	indexOfSessionTableNamesInSavedObjects
private String	name
private boolean	needTarget
private ValueNode	offset
private OrderByList	orderByList
public static final int	READ_ONLY
private String	statementType
private ArrayList<TableDescriptor>	statsToUpdate List of `TableDescriptor`s for base tables whose associated indexes should be checked for stale statistics.
pack-priv static final int	UNSPECIFIED
private List<String>	updatableColumns There can only be a list of updatable columns when FOR UPDATE is specified as part of the cursor specification.
pack-priv static final int	UPDATE
private int	updateMode
private FromTable	updateTable

Inherited from org.apache.derby.impl.sql.compile.DMLStatementNode:: resultSet

Constructor Summary

Access	Constructor and Description
pack-priv	CursorNode(String Type of statement (SELECT, UPDATE, INSERT) statementType, ResultSetNode A ResultSetNode specifying the result set for the cursor resultSet, String The name of the cursor, null if no name name, OrderByList The order by list for the cursor, null if no order by list orderByList, ValueNode The value of a if present offset, ValueNode The value of a if present fetchFirst, boolean True if the offset/fetchFirst clauses come from JDBC limit/offset escape syntax hasJDBClimitClause, int The user-specified update mode for the cursor, for example, CursorNode.READ_ONLY updateMode, String[] The array of updatable columns specified by the user in the FOR UPDATE clause, null if no updatable columns specified. May only be provided if the updateMode parameter is CursorNode.UPDATE. updatableColumns, boolean True if this cursor is the driving left-join of a MERGE statement forMergeStatement, ContextManager The context manager cm) Constructor for a CursorNode

Access

Constructor and Description

pack-priv

CursorNode(String

Type of statement (SELECT, UPDATE, INSERT)

statementType, ResultSetNode

A ResultSetNode specifying the result set for the cursor

resultSet, String

The name of the cursor, null if no name

name, OrderByList

The order by list for the cursor, null if no order by list

orderByList, ValueNode

The value of a if present

offset, ValueNode

The value of a if present

fetchFirst, boolean

True if the offset/fetchFirst clauses come from JDBC limit/offset escape syntax

hasJDBClimitClause, int

The user-specified update mode for the cursor, for example, CursorNode.READ_ONLY

updateMode, String[]

The array of updatable columns specified by the user in the FOR UPDATE clause, null if no updatable columns specified. May only be provided if the updateMode parameter is CursorNode.UPDATE.

updatableColumns, boolean

True if this cursor is the driving left-join of a MERGE statement

forMergeStatement, ContextManager

The context manager

cm)

Constructor for a CursorNode

Method Summary

Modifier and Type	Method and Description
pack-priv void	acceptChildren(Visitor the visitor v) Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.acceptChildren. Accept the visitor for all visitable children of this node.
pack-priv int	Returns: either (NEED_CURSOR_ACTIVATION activationKind() Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.activationKind. Returns the type of activation this class generates.
public void	bindStatement() Overrides org.apache.derby.impl.sql.compile.StatementNode.bindStatement. Bind this CursorNode.
private void	bindUpdateColumns(FromTable The underlying target table targetTable) Bind the update columns by their names to the target table of the cursor specification.
private void	collectTablesWithPossiblyStaleStats() Collects table descriptors for base tables whose index statistics we want to check for staleness (or to create).
private int	Returns: the known update mode for the cursor. determineUpdateMode(DataDictionary dataDictionary) Take a cursor and determine if it is UPDATE or READ_ONLY based on the shape of the cursor specification.
pack-priv void	generate(ActivationClassBuilder The ActivationClassBuilder for the class being built acb, MethodBuilder The method the generated code is to go into mb) Overrides org.apache.derby.impl.sql.compile.QueryTreeNode.generate. Do code generation for this CursorNode
public Object	Returns: the cursor info getCursorInfo() Overrides org.apache.derby.impl.sql.compile.StatementNode.getCursorInfo. Get information about this cursor.
protected ArrayList<String>	getSessionSchemaTableNamesForCursor()
pack-priv String	getUpdateBaseTableName()
pack-priv String	getUpdateExposedTableName()
pack-priv int	getUpdateMode()
pack-priv String	getUpdateSchemaName()
pack-priv String	getXML()
public boolean	Returns: boolean Whether or not this Statement requires a set/clear savepoint needsSavepoint() Overrides org.apache.derby.impl.sql.compile.StatementNode.needsSavepoint. Returns whether or not this Statement requires a set/clear savepoint around its execution.
public void	optimizeStatement() Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.optimizeStatement. Optimize a DML statement (which is the only type of statement that should need optimizing, I think).
pack-priv void	printSubNodes(int The depth of this node in the tree depth) Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.printSubNodes. Prints the sub-nodes of this object.
public boolean	Returns: true if references SESSION schema tables, else false referencesSessionSchema() Overrides org.apache.derby.impl.sql.compile.QueryTreeNode.referencesSessionSchema. Return true if the node references SESSION schema tables (temporary or permanent)
pack-priv String	statementToString() Implements abstract org.apache.derby.impl.sql.compile.StatementNode.statementToString.
public String	Returns: This object as a String toString() Overrides org.apache.derby.impl.sql.compile.StatementNode.toString. Convert this object to a String.
public TableDescriptor[]	Returns: A list of table descriptors (potentially empty). updateIndexStatisticsFor() Overrides org.apache.derby.impl.sql.compile.StatementNode.updateIndexStatisticsFor. Returns a list of base tables for which the index statistics of the associated indexes should be updated.
private static String	Returns: A String representing the update mode. updateModeString(int An updateMode identifier updateMode) Support routine for translating an updateMode identifier to a String

Inherited from org.apache.derby.impl.sql.compile.DMLStatementNode:: bind bindExpressions bindExpressionsWithTables bindResultSetsWithTables bindTables generateParameterValueSet getPrivType getResultSetNode isAtomic makeResultDescription

Field Detail

checkIndexStats	back to summary
private boolean checkIndexStats

fetchFirst	back to summary
private ValueNode fetchFirst

forMergeStatement	back to summary
private boolean forMergeStatement

hasJDBClimitClause	back to summary
private boolean hasJDBClimitClause

indexOfSessionTableNamesInSavedObjects	back to summary
private int indexOfSessionTableNamesInSavedObjects

name	back to summary
private String name

needTarget	back to summary
private boolean needTarget

offset	back to summary
private ValueNode offset

orderByList	back to summary
private OrderByList orderByList

READ_ONLY	back to summary
public static final int READ_ONLY

statementType	back to summary
private String statementType

statsToUpdate	back to summary
private ArrayList<TableDescriptor> statsToUpdate List of `TableDescriptor`s for base tables whose associated indexes should be checked for stale statistics.

UNSPECIFIED	back to summary
pack-priv static final int UNSPECIFIED

updatableColumns	back to summary
private List<String> updatableColumns There can only be a list of updatable columns when FOR UPDATE is specified as part of the cursor specification.

UPDATE	back to summary
pack-priv static final int UPDATE

updateMode	back to summary
private int updateMode

updateTable	back to summary
private FromTable updateTable

Constructor Detail

CursorNode	back to summary
pack-priv CursorNode(String statementType, ResultSetNode resultSet, String name, OrderByList orderByList, ValueNode offset, ValueNode fetchFirst, boolean hasJDBClimitClause, int updateMode, String[] updatableColumns, boolean forMergeStatement, ContextManager cm) Constructor for a CursorNode Parameters statementType:String Type of statement (SELECT, UPDATE, INSERT) resultSet:ResultSetNode A ResultSetNode specifying the result set for the cursor name:String The name of the cursor, null if no name orderByList:OrderByList The order by list for the cursor, null if no order by list offset:ValueNode The value of a if present fetchFirst:ValueNode The value of a if present hasJDBClimitClause:boolean True if the offset/fetchFirst clauses come from JDBC limit/offset escape syntax updateMode:int The user-specified update mode for the cursor, for example, CursorNode.READ_ONLY updatableColumns:String[] The array of updatable columns specified by the user in the FOR UPDATE clause, null if no updatable columns specified. May only be provided if the updateMode parameter is CursorNode.UPDATE. forMergeStatement:boolean True if this cursor is the driving left-join of a MERGE statement cm:ContextManager The context manager

CursorNode

back to summary

pack-priv CursorNode(String statementType, ResultSetNode resultSet, String name, OrderByList orderByList, ValueNode offset, ValueNode fetchFirst, boolean hasJDBClimitClause, int updateMode, String[] updatableColumns, boolean forMergeStatement, ContextManager cm)

Constructor for a CursorNode

Parameters

statementType:String: Type of statement (SELECT, UPDATE, INSERT)
resultSet:ResultSetNode: A ResultSetNode specifying the result set for the cursor
name:String: The name of the cursor, null if no name
orderByList:OrderByList: The order by list for the cursor, null if no order by list
offset:ValueNode: The value of a if present
fetchFirst:ValueNode: The value of a if present
hasJDBClimitClause:boolean: True if the offset/fetchFirst clauses come from JDBC limit/offset escape syntax
updateMode:int: The user-specified update mode for the cursor, for example, CursorNode.READ_ONLY
updatableColumns:String[]: The array of updatable columns specified by the user in the FOR UPDATE clause, null if no updatable columns specified. May only be provided if the updateMode parameter is CursorNode.UPDATE.
forMergeStatement:boolean: True if this cursor is the driving left-join of a MERGE statement
cm:ContextManager: The context manager

Method Detail

acceptChildren	back to summary
pack-priv void acceptChildren(Visitor v) throws StandardException Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.acceptChildren. Accept the visitor for all visitable children of this node. Parameters v:Visitor the visitor Annotations @Override Exceptions StandardException: on error

acceptChildren

back to summary

pack-priv void acceptChildren(Visitor v) throws StandardException

Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.acceptChildren.

Accept the visitor for all visitable children of this node.

Parameters

v:Visitor: the visitor

Annotations

@Override

Exceptions

StandardException:: on error

activationKind	back to summary
pack-priv int activationKind() Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.activationKind. Returns the type of activation this class generates. Returns:int either (NEED_CURSOR_ACTIVATION Annotations @Override Exceptions StandardException: Thrown on error

activationKind

back to summary

pack-priv int activationKind()

Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.activationKind.

Returns the type of activation this class generates.

Returns:int

either (NEED_CURSOR_ACTIVATION

Annotations

@Override

Exceptions

StandardException:: Thrown on error

bindStatement	back to summary
public void bindStatement() throws StandardException Overrides org.apache.derby.impl.sql.compile.StatementNode.bindStatement. Bind this CursorNode. This means looking up tables and columns and getting their types, and figuring out the result types of all expressions, as well as doing view resolution, permissions checking, etc. It also includes determining whether an UNSPECIFIED cursor is updatable or not, and verifying that an UPDATE cursor actually is. Annotations @Override Exceptions StandardException: Thrown on error

bindStatement

back to summary

public void bindStatement() throws StandardException

Overrides org.apache.derby.impl.sql.compile.StatementNode.bindStatement.

Bind this CursorNode. This means looking up tables and columns and getting their types, and figuring out the result types of all expressions, as well as doing view resolution, permissions checking, etc. It also includes determining whether an UNSPECIFIED cursor is updatable or not, and verifying that an UPDATE cursor actually is.

Annotations

@Override

Exceptions

StandardException:: Thrown on error

bindUpdateColumns	back to summary
private void bindUpdateColumns(FromTable targetTable) throws StandardException Bind the update columns by their names to the target table of the cursor specification. Doesn't check for duplicates in the list, although it could... Revisit If the list is empty, should it expand it out? at present, it leaves it empty. Parameters targetTable:FromTable The underlying target table Exceptions StandardException: Thrown on error

bindUpdateColumns

back to summary

private void bindUpdateColumns(FromTable targetTable) throws StandardException

Bind the update columns by their names to the target table of the cursor specification. Doesn't check for duplicates in the list, although it could...

Revisit

If the list is empty, should it expand it out? at present, it leaves it empty.

Parameters

targetTable:FromTable: The underlying target table

Exceptions

StandardException:: Thrown on error

collectTablesWithPossiblyStaleStats	back to summary
private void collectTablesWithPossiblyStaleStats() throws StandardException Collects table descriptors for base tables whose index statistics we want to check for staleness (or to create).

determineUpdateMode	back to summary
private int determineUpdateMode(DataDictionary dataDictionary) throws StandardException Take a cursor and determine if it is UPDATE or READ_ONLY based on the shape of the cursor specification. The following conditions make a cursor read only: if it says FOR READ ONLY if it says ORDER BY if its query specification is not read only. At present this is explicitly tested here, with these conditions. At some future point in time, this checking ought to be moved into the ResultSet nodes themselves. The conditions for a query spec. not to be read only include: if it has a set operation such as UNION or INTERSECT, i.e. does not have a single outermost SELECT if it does not have exactly 1 table in its FROM list; 0 tables would occur if we ever support a SELECT without a FROM e.g., for generating a row without an underlying table (like what we do for an INSERT of a VALUES list); >1 tables occurs when joins are in the tree. if the table in its FROM list is not a base table (REMIND when views/from subqueries are added, this should be relaxed to be that the table is not updatable) if it has a GROUP BY or HAVING (NOTE I am assuming that if and aggregate is detected in a SELECT w/o a GROUP BY, one has been added to show that the whole table is a group) NOTE that cursors are updatable even if none of the columns in the select are updatable -- what they care about is the updatability of the columns of the target table. Returns:int the known update mode for the cursor. Exceptions StandardException: Thrown on error

determineUpdateMode

back to summary

private int determineUpdateMode(DataDictionary dataDictionary) throws StandardException

Take a cursor and determine if it is UPDATE or READ_ONLY based on the shape of the cursor specification.

The following conditions make a cursor read only:

if it says FOR READ ONLY
if it says ORDER BY
if its query specification is not read only. At present this is explicitly tested here, with these conditions. At some future point in time, this checking ought to be moved into the ResultSet nodes themselves. The conditions for a query spec. not to be read only include:
- if it has a set operation such as UNION or INTERSECT, i.e. does not have a single outermost SELECT
- if it does not have exactly 1 table in its FROM list; 0 tables would occur if we ever support a SELECT without a FROM e.g., for generating a row without an underlying table (like what we do for an INSERT of a VALUES list); >1 tables occurs when joins are in the tree.
- if the table in its FROM list is not a base table (REMIND when views/from subqueries are added, this should be relaxed to be that the table is not updatable)
- if it has a GROUP BY or HAVING (NOTE I am assuming that if and aggregate is detected in a SELECT w/o a GROUP BY, one has been added to show that the whole table is a group)
- NOTE that cursors are updatable even if none of the columns in the select are updatable -- what they care about is the updatability of the columns of the target table.

Returns:int

the known update mode for the cursor.

Exceptions

StandardException:: Thrown on error

generate	back to summary
pack-priv void generate(ActivationClassBuilder acb, MethodBuilder mb) throws StandardException Overrides org.apache.derby.impl.sql.compile.QueryTreeNode.generate. Do code generation for this CursorNode Parameters acb:ActivationClassBuilder The ActivationClassBuilder for the class being built mb:MethodBuilder The method the generated code is to go into Annotations @Override Exceptions StandardException: Thrown on error

generate

back to summary

pack-priv void generate(ActivationClassBuilder acb, MethodBuilder mb) throws StandardException

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

Do code generation for this CursorNode

Parameters

acb:ActivationClassBuilder: The ActivationClassBuilder for the class being built
mb:MethodBuilder: The method the generated code is to go into

Annotations

@Override

Exceptions

StandardException:: Thrown on error

getCursorInfo	back to summary
public Object getCursorInfo() throws StandardException Overrides org.apache.derby.impl.sql.compile.StatementNode.getCursorInfo. Get information about this cursor. For sps, this is info saved off of the original query tree (the one for the underlying query). Returns:Object the cursor info Annotations @Override Exceptions StandardException: thrown if generation fails

getCursorInfo

back to summary

public Object getCursorInfo() throws StandardException

Overrides org.apache.derby.impl.sql.compile.StatementNode.getCursorInfo.

Get information about this cursor. For sps, this is info saved off of the original query tree (the one for the underlying query).

Returns:Object

the cursor info

Annotations

@Override

Exceptions

StandardException:: thrown if generation fails

getSessionSchemaTableNamesForCursor	back to summary
protected ArrayList<String> getSessionSchemaTableNamesForCursor() throws StandardException

getUpdateBaseTableName	back to summary
pack-priv String getUpdateBaseTableName()

getUpdateExposedTableName	back to summary
pack-priv String getUpdateExposedTableName() throws StandardException

getUpdateMode	back to summary
pack-priv int getUpdateMode()

getUpdateSchemaName	back to summary
pack-priv String getUpdateSchemaName() throws StandardException

getXML	back to summary
pack-priv String getXML()

needsSavepoint	back to summary
public boolean needsSavepoint() Overrides org.apache.derby.impl.sql.compile.StatementNode.needsSavepoint. Returns whether or not this Statement requires a set/clear savepoint around its execution. The following statement "types" do not require them: Cursor - unnecessary and won't work in a read only environment Xact - savepoint will get blown away underneath us during commit/rollback Returns:boolean boolean Whether or not this Statement requires a set/clear savepoint Annotations @Override

needsSavepoint

back to summary

public boolean needsSavepoint()

Overrides org.apache.derby.impl.sql.compile.StatementNode.needsSavepoint.

Returns whether or not this Statement requires a set/clear savepoint around its execution. The following statement "types" do not require them: Cursor - unnecessary and won't work in a read only environment Xact - savepoint will get blown away underneath us during commit/rollback

Returns:boolean

boolean Whether or not this Statement requires a set/clear savepoint

Annotations

@Override

optimizeStatement	back to summary
public void optimizeStatement() throws StandardException Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.optimizeStatement. Optimize a DML statement (which is the only type of statement that should need optimizing, I think). This method over-rides the one in QueryTreeNode. This method takes a bound tree, and returns an optimized tree. It annotates the bound tree rather than creating an entirely new tree. Throws an exception if the tree is not bound, or if the binding is out of date. Annotations @Override Exceptions StandardException: Thrown on error

optimizeStatement

back to summary

public void optimizeStatement() throws StandardException

Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.optimizeStatement.

Optimize a DML statement (which is the only type of statement that should need optimizing, I think). This method over-rides the one in QueryTreeNode. This method takes a bound tree, and returns an optimized tree. It annotates the bound tree rather than creating an entirely new tree. Throws an exception if the tree is not bound, or if the binding is out of date.

Annotations

@Override

Exceptions

StandardException:: Thrown on error

printSubNodes	back to summary
pack-priv void printSubNodes(int depth) Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.printSubNodes. Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work. Parameters depth:int The depth of this node in the tree Annotations @Override

printSubNodes

back to summary

pack-priv void printSubNodes(int depth)

Overrides org.apache.derby.impl.sql.compile.DMLStatementNode.printSubNodes.

Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.

Parameters

depth:int: The depth of this node in the tree

Annotations

@Override

referencesSessionSchema	back to summary
public boolean referencesSessionSchema() throws StandardException Overrides org.apache.derby.impl.sql.compile.QueryTreeNode.referencesSessionSchema. Return true if the node references SESSION schema tables (temporary or permanent) Returns:boolean true if references SESSION schema tables, else false Annotations @Override Exceptions StandardException: Thrown on error

referencesSessionSchema

back to summary

public boolean referencesSessionSchema() throws StandardException

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

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

Returns:boolean

true if references SESSION schema tables, else false

Annotations

@Override

Exceptions

StandardException:: Thrown on error

statementToString	back to summary
pack-priv String statementToString() Implements abstract org.apache.derby.impl.sql.compile.StatementNode.statementToString.

toString	back to summary
public String toString() Overrides org.apache.derby.impl.sql.compile.StatementNode.toString. Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing. Returns:String This object as a String Annotations @Override

toString

back to summary

public String toString()

Overrides org.apache.derby.impl.sql.compile.StatementNode.toString.

Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

Returns:String

This object as a String

Annotations

@Override

updateIndexStatisticsFor	back to summary
public TableDescriptor[] updateIndexStatisticsFor() throws StandardException Overrides org.apache.derby.impl.sql.compile.StatementNode.updateIndexStatisticsFor. Returns a list of base tables for which the index statistics of the associated indexes should be updated. Returns:TableDescriptor[] A list of table descriptors (potentially empty). Annotations @Override Exceptions StandardException: if accessing the index descriptors of a base table fails

updateIndexStatisticsFor

back to summary

public TableDescriptor[] updateIndexStatisticsFor() throws StandardException

Overrides org.apache.derby.impl.sql.compile.StatementNode.updateIndexStatisticsFor.

Returns a list of base tables for which the index statistics of the associated indexes should be updated.

Returns:TableDescriptor[]

A list of table descriptors (potentially empty).

Annotations

@Override

Exceptions

StandardException:: if accessing the index descriptors of a base table fails

updateModeString	back to summary
private static String updateModeString(int updateMode) Support routine for translating an updateMode identifier to a String Parameters updateMode:int An updateMode identifier Returns:String A String representing the update mode.

updateModeString

back to summary

private static String updateModeString(int updateMode)

Support routine for translating an updateMode identifier to a String

Parameters

updateMode:int: An updateMode identifier

Returns:String

A String representing the update mode.

public Class CursorNode

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail