Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.diag.StatementCache

public final Class StatementCache

StatementCache is a virtual table that shows the contents of the SQL statement cache. This virtual table can be invoked by calling it directly.

 select * from new org.apache.derby.diag.StatementCache() t

The StatementCache virtual table has the following columns:

ID CHAR(36) - not nullable. Internal identifier of the compiled statement.
SCHEMANAME VARCHAR(128) - nullable. Schema the statement was compiled in.
SQL_TEXT VARCHAR(32672) - not nullable. Text of the statement
UNICODE BIT/BOOLEAN - not nullable. Always true.
VALID BIT/BOOLEAN - not nullable. True if the statement is currently valid, false otherwise
COMPILED_AT TIMESTAMP nullable - time statement was compiled, requires STATISTICS TIMING to be enabled.

The internal identifier of a cached statement matches the toString() method of a PreparedStatement object for a Derby database.

This class also provides a static method to empty the statement cache, StatementCache.emptyCache()

Modifier and Type	Field and Description
private static final ResultColumnDescriptor[]	columnInfo
private GenericPreparedStatement	currentPs
private Vector<GenericPreparedStatement>	data
private static final ResultSetMetaData	metadata
private int	position
private boolean	wasNull

Modifier and Type

Field and Description

private static final ResultColumnDescriptor[]

columnInfo

private GenericPreparedStatement

currentPs

private Vector<GenericPreparedStatement>

data

private static final ResultSetMetaData

metadata

private int

position

private boolean

wasNull

Constructor Summary

Access	Constructor and Description
public	StatementCache()

Method Summary

Modifier and Type	Method and Description
public void	close() Implements java.sql.ResultSet.close. Releases this `ResultSet` object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.
public boolean	getBoolean(int the first column is 1, the second is 2, ... colId) Overrides org.apache.derby.vti.VTITemplate.getBoolean. Implements java.sql.ResultSet.getBoolean. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `boolean` in the Java programming language.
private static Context	getContextOrNull(final String contextID) Must be private so that user code can't call this entry point.
public ResultSetMetaData	getMetaData() Overrides org.apache.derby.vti.VTITemplate.getMetaData. Implements java.sql.ResultSet.getMetaData. Retrieves the number, types and properties of this `ResultSet` object's columns.
public String	getString(int the first column is 1, the second is 2, ... colId) Overrides org.apache.derby.vti.VTITemplate.getString. Implements java.sql.ResultSet.getString. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `String` in the Java programming language.
public Timestamp	getTimestamp(int the first column is 1, the second is 2, ... colId) Overrides org.apache.derby.vti.VTITemplate.getTimestamp. Implements java.sql.ResultSet.getTimestamp. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `java.sql.Timestamp` object in the Java programming language.
public boolean	next() Implements java.sql.ResultSet.next. Moves the cursor forward one row from its current position.
public boolean	wasNull() Overrides org.apache.derby.vti.VTITemplate.wasNull. Implements java.sql.ResultSet.wasNull. Reports whether the last column read had a value of SQL `NULL`.

Modifier and Type

Method and Description

public void

close()

Implements java.sql.ResultSet.close.

Releases this ResultSet object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.

public boolean

getBoolean(int

the first column is 1, the second is 2, ...

colId)

Overrides org.apache.derby.vti.VTITemplate.getBoolean.

Implements java.sql.ResultSet.getBoolean.

Retrieves the value of the designated column in the current row of this ResultSet object as a boolean in the Java programming language.

private static Context

getContextOrNull(final String contextID)

Must be private so that user code can't call this entry point.

public ResultSetMetaData

getMetaData()

Overrides org.apache.derby.vti.VTITemplate.getMetaData.

Implements java.sql.ResultSet.getMetaData.

Retrieves the number, types and properties of this ResultSet object's columns.

public String

getString(int

the first column is 1, the second is 2, ...

colId)

Overrides org.apache.derby.vti.VTITemplate.getString.

Implements java.sql.ResultSet.getString.

Retrieves the value of the designated column in the current row of this ResultSet object as a String in the Java programming language.

public Timestamp

getTimestamp(int

the first column is 1, the second is 2, ...

colId)

Overrides org.apache.derby.vti.VTITemplate.getTimestamp.

Implements java.sql.ResultSet.getTimestamp.

Retrieves the value of the designated column in the current row of this ResultSet object as a java.sql.Timestamp object in the Java programming language.

public boolean

next()

Implements java.sql.ResultSet.next.

Moves the cursor forward one row from its current position.

public boolean

wasNull()

Overrides org.apache.derby.vti.VTITemplate.wasNull.

Implements java.sql.ResultSet.wasNull.

Reports whether the last column read had a value of SQL NULL.

columnInfo	back to summary
private static final ResultColumnDescriptor[] columnInfo

columnInfo

back to summary

private static final ResultColumnDescriptor[] columnInfo

currentPs	back to summary
private GenericPreparedStatement currentPs

currentPs

back to summary

private GenericPreparedStatement currentPs

data	back to summary
private Vector<GenericPreparedStatement> data

data

back to summary

private Vector<GenericPreparedStatement> data

metadata

back to summary

private static final ResultSetMetaData metadata

position	back to summary
private int position

position

back to summary

private int position

wasNull	back to summary
private boolean wasNull

wasNull

back to summary

private boolean wasNull

Constructor Detail

StatementCache	back to summary
public StatementCache() throws StandardException

Method Detail

close back to summary

close	back to summary
public void close() Implements java.sql.ResultSet.close. Doc from java.sql.ResultSet.close. Releases this `ResultSet` object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed. The closing of a `ResultSet` object does not close the `Blob`, `Clob` or `NClob` objects created by the `ResultSet`. `Blob`, `Clob` or `NClob` objects remain valid for at least the duration of the transaction in which they are created, unless their `free` method is invoked. When a `ResultSet` is closed, any `ResultSetMetaData` instances that were created by calling the `getMetaData` method remain accessible. Note A `ResultSet` object is automatically closed by the `Statement` object that generated it when that `Statement` object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results. Calling the method `close` on a `ResultSet` object that is already closed is a no-op.

public void close()

Implements java.sql.ResultSet.close.

Doc from java.sql.ResultSet.close.

Releases this ResultSet object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.

The closing of a ResultSet object does not close the Blob, Clob or NClob objects created by the ResultSet. Blob, Clob or NClob objects remain valid for at least the duration of the transaction in which they are created, unless their free method is invoked.

When a ResultSet is closed, any ResultSetMetaData instances that were created by calling the getMetaData method remain accessible.

Note

A ResultSet object is automatically closed by the Statement object that generated it when that Statement object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results.

Calling the method close on a ResultSet object that is already closed is a no-op.

getBoolean back to summary

getBoolean	back to summary
public boolean getBoolean(int colId) Overrides org.apache.derby.vti.VTITemplate.getBoolean. Implements java.sql.ResultSet.getBoolean. Doc from java.sql.ResultSet.getBoolean. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `boolean` in the Java programming language. If the designated column has a datatype of CHAR or VARCHAR and contains a "0" or has a datatype of BIT, TINYINT, SMALLINT, INTEGER or BIGINT and contains a 0, a value of `false` is returned. If the designated column has a datatype of CHAR or VARCHAR and contains a "1" or has a datatype of BIT, TINYINT, SMALLINT, INTEGER or BIGINT and contains a 1, a value of `true` is returned. Parameters colId:int the first column is 1, the second is 2, ... Returns:boolean the column value; if the value is SQL `NULL`, the value returned is `false`

public boolean getBoolean(int colId)

Overrides org.apache.derby.vti.VTITemplate.getBoolean.

Implements java.sql.ResultSet.getBoolean.

Doc from java.sql.ResultSet.getBoolean.

Retrieves the value of the designated column in the current row of this ResultSet object as a boolean in the Java programming language.

If the designated column has a datatype of CHAR or VARCHAR and contains a "0" or has a datatype of BIT, TINYINT, SMALLINT, INTEGER or BIGINT and contains a 0, a value of false is returned. If the designated column has a datatype of CHAR or VARCHAR and contains a "1" or has a datatype of BIT, TINYINT, SMALLINT, INTEGER or BIGINT and contains a 1, a value of true is returned.

Parameters

colId:int: the first column is 1, the second is 2, ...

Returns:boolean

the column value; if the value is SQL NULL, the value returned is false

getContextOrNull	back to summary
private static Context getContextOrNull(final String contextID) Must be private so that user code can't call this entry point.

getMetaData back to summary

public ResultSetMetaData getMetaData()

Overrides org.apache.derby.vti.VTITemplate.getMetaData.

Implements java.sql.ResultSet.getMetaData.

Doc from java.sql.ResultSet.getMetaData.

Retrieves the number, types and properties of this ResultSet object's columns.

Returns:ResultSetMetaData: the description of this ResultSet object's columns

getString back to summary

getString	back to summary
public String getString(int colId) Overrides org.apache.derby.vti.VTITemplate.getString. Implements java.sql.ResultSet.getString. Doc from java.sql.ResultSet.getString. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `String` in the Java programming language. Parameters colId:int the first column is 1, the second is 2, ... Returns:String the column value; if the value is SQL `NULL`, the value returned is `null`

public String getString(int colId)

Overrides org.apache.derby.vti.VTITemplate.getString.

Implements java.sql.ResultSet.getString.

Doc from java.sql.ResultSet.getString.

Retrieves the value of the designated column in the current row of this ResultSet object as a String in the Java programming language.

Parameters

colId:int: the first column is 1, the second is 2, ...

Returns:String

the column value; if the value is SQL NULL, the value returned is null

getTimestamp back to summary

getTimestamp	back to summary
public Timestamp getTimestamp(int colId) Overrides org.apache.derby.vti.VTITemplate.getTimestamp. Implements java.sql.ResultSet.getTimestamp. Doc from java.sql.ResultSet.getTimestamp. Retrieves the value of the designated column in the current row of this `ResultSet` object as a `java.sql.Timestamp` object in the Java programming language. Parameters colId:int the first column is 1, the second is 2, ... Returns:Timestamp the column value; if the value is SQL `NULL`, the value returned is `null`

public Timestamp getTimestamp(int colId)

Overrides org.apache.derby.vti.VTITemplate.getTimestamp.

Implements java.sql.ResultSet.getTimestamp.

Doc from java.sql.ResultSet.getTimestamp.

Retrieves the value of the designated column in the current row of this ResultSet object as a java.sql.Timestamp object in the Java programming language.

Parameters

colId:int: the first column is 1, the second is 2, ...

Returns:Timestamp

the column value; if the value is SQL NULL, the value returned is null

next back to summary

next	back to summary
public boolean next() Implements java.sql.ResultSet.next. Doc from java.sql.ResultSet.next. Moves the cursor forward one row from its current position. A `ResultSet` cursor is initially positioned before the first row; the first call to the method `next` makes the first row the current row; the second call makes the second row the current row, and so on. When a call to the `next` method returns `false`, the cursor is positioned after the last row. Any invocation of a `ResultSet` method which requires a current row will result in a `SQLException` being thrown. If the result set type is `TYPE_FORWARD_ONLY`, it is vendor specified whether their JDBC driver implementation will return `false` or throw an `SQLException` on a subsequent call to `next`. If an input stream is open for the current row, a call to the method `next` will implicitly close it. A `ResultSet` object's warning chain is cleared when a new row is read. Returns:boolean `true` if the new current row is valid; `false` if there are no more rows

public boolean next()

Implements java.sql.ResultSet.next.

Doc from java.sql.ResultSet.next.

Moves the cursor forward one row from its current position. A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.

When a call to the next method returns false, the cursor is positioned after the last row. Any invocation of a ResultSet method which requires a current row will result in a SQLException being thrown. If the result set type is TYPE_FORWARD_ONLY, it is vendor specified whether their JDBC driver implementation will return false or throw an SQLException on a subsequent call to next.

If an input stream is open for the current row, a call to the method next will implicitly close it. A ResultSet object's warning chain is cleared when a new row is read.

Returns:boolean: true if the new current row is valid; false if there are no more rows

wasNull back to summary

wasNull	back to summary
public boolean wasNull() Overrides org.apache.derby.vti.VTITemplate.wasNull. Implements java.sql.ResultSet.wasNull. Doc from java.sql.ResultSet.wasNull. Reports whether the last column read had a value of SQL `NULL`. Note that you must first call one of the getter methods on a column to try to read its value and then call the method `wasNull` to see if the value read was SQL `NULL`. Returns:boolean `true` if the last column value read was SQL `NULL` and `false` otherwise

public boolean wasNull()

Overrides org.apache.derby.vti.VTITemplate.wasNull.

Implements java.sql.ResultSet.wasNull.

Doc from java.sql.ResultSet.wasNull.

Reports whether the last column read had a value of SQL NULL. Note that you must first call one of the getter methods on a column to try to read its value and then call the method wasNull to see if the value read was SQL NULL.

Returns:boolean: true if the last column value read was SQL NULL and false otherwise

public final Class StatementCache

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail