org.apache.derby.impl.sql.compile

Class StatementNode

java.lang.Object

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

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

All Implemented Interfaces:

Visitable

Direct Known Subclasses:

CursorNode, InsertNode, MergeNode, UpdateNode

public abstract class StatementNode
extends QueryTreeNode

A StatementNode represents a single statement in the language. It is the top node for any statement.

StatementNode controls the class generation for query tree nodes.

Method Summary

Modifier and Type	Method and Description
void	bindStatement() Perform the binding operation statement.
java.lang.String	executeSchemaName() Returns name of schema in EXECUTE STATEMENT command.
java.lang.String	executeStatementName() Returns the name of statement in EXECUTE STATEMENT command.
GeneratedClass	generate(ByteArray byteCode) Do code generation for this statement.
java.lang.Object	getCursorInfo() Get an object with information about the cursor if there is one.
java.lang.String	getSPSName() Get the name of the SPS that is used to execute this statement.
boolean	isAtomic() By default, assume StatementNodes are atomic.
ResultDescription	makeResultDescription() Only DML statements have result descriptions - for all others return null.
boolean	needsSavepoint() Returns whether or not this Statement requires a set/clear savepoint around its execution.
void	optimizeStatement() Generates an optimized statement from a bound StatementNode.
java.lang.String	toString() Convert this object to a String.
TableDescriptor[]	updateIndexStatisticsFor() Returns a list of base tables for which the index statistics of the associated indexes should be updated.

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

accept, addTag, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, createTypeDependency, getBeginOffset, getDataDictionary, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getUDTDesc, makeConstantAction, makeTableName, makeTableName, optimizerTracingIsOn, orReliability, referencesSessionSchema, setBeginOffset, setEndOffset, taggedWith, treePrint

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

isAtomic

public boolean isAtomic()
                 throws StandardException

By default, assume StatementNodes are atomic. The rare statements that aren't atomic (e.g. CALL method()) override this.

Overrides:

isAtomic in class QueryTreeNode

Returns:

true if the statement is atomic

Throws:

StandardException - Thrown on error

needsSavepoint

public boolean 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

ONLY CALLABLE AFTER GENERATION

This implementation returns true, sub-classes can override the method to not require a savepoint.

Returns:

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

getSPSName

public java.lang.String getSPSName()

Get the name of the SPS that is used to execute this statement. Only relevant for an ExecSPSNode -- otherwise, returns null.

Returns:

the name of the underlying sps

executeStatementName

public java.lang.String executeStatementName()

Returns the name of statement in EXECUTE STATEMENT command. Returns null for all other commands.

Returns:

String null unless overridden for Execute Statement command

executeSchemaName

public java.lang.String executeSchemaName()

Returns name of schema in EXECUTE STATEMENT command. Returns null for all other commands.

Returns:

String schema for EXECUTE STATEMENT null for all others

makeResultDescription

public ResultDescription makeResultDescription()

Only DML statements have result descriptions - for all others return null. This method is overridden in DMLStatementNode.

Returns:

null

getCursorInfo

public java.lang.Object getCursorInfo()
                               throws StandardException

Get an object with information about the cursor if there is one.

Throws:

StandardException

toString

public java.lang.String toString()

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

Overrides:

toString in class QueryTreeNode

Returns:

This object as a String

bindStatement

public void bindStatement()
                   throws StandardException

Perform the binding operation statement. Binding consists of permissions checking, view resolution, datatype resolution, and creation of a dependency list (for determining whether a tree or plan is still up to date). This bindStatement() method does nothing. Each StatementNode type that can appear at the top of a tree can override this method with its own bindStatement() method that does "something".

Throws:

StandardException - Thrown on error

optimizeStatement

public void optimizeStatement()
                       throws StandardException

Generates an optimized statement from a bound StatementNode. Actually, it annotates the tree in place rather than generating a new tree. For non-optimizable statements (for example, CREATE TABLE), return the bound tree without doing anything. For optimizable statements, this method will be over-ridden in the statement's root node (DMLStatementNode in all cases we know about so far). Throws an exception if the tree is not bound, or if the binding is out of date.

Throws:

StandardException - Thrown on error

generate

public GeneratedClass generate(ByteArray byteCode)
                        throws StandardException

Do code generation for this statement.

Parameters:

byteCode - the generated byte code for this statement. if non-null, then the byte code is saved here.

Returns:

A GeneratedClass for this statement

Throws:

StandardException - Thrown on error

updateIndexStatisticsFor

public TableDescriptor[] updateIndexStatisticsFor()
                                           throws StandardException

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

This default implementation always returns an empty list.

Returns:

A list of table descriptors (potentially empty).

Throws:

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