public final class JDBCStatementCache
extends java.lang.Object
The entries in the cache contains objects implementing the
java.sql.PreparedStatement
interface, and they are inserted with
a key object implementing the interface StatementKey
. The cached
objects can be either java.sql.PreparedStatement
or
java.sql.CallableStatement
. These two should be separated by
using different types of keys.
The cache only contains free statement objects, and on a successful request
for a cached statement the statement is removed from the cache. The cache is
not intended to hold duplicate statements. The physical prepared statement
should be (re-)inserted into the cache when close
is called on
the logical prepared statement using it.
There is a maximum number of cached statements associated with the cache. If this number is exceeded, the oldest entry will be thrown out. One can always throw out an entry, because the fact that it is in the cache means it is free and not in use.
Modifier and Type | Class and Description |
---|---|
private static class |
JDBCStatementCache.BoundedLinkedHashMap
A
LinkedHashMap with an upper bound on the number of entries. |
Modifier and Type | Field and Description |
---|---|
private java.util.LinkedHashMap<StatementKey,java.sql.PreparedStatement> |
statements
Structure holding the cached prepared statement objects.
|
Constructor and Description |
---|
JDBCStatementCache(int maxSize)
Creates a new, empty JDBC statement cache.
|
Modifier and Type | Method and Description |
---|---|
boolean |
cacheStatement(StatementKey statementKey,
java.sql.PreparedStatement ps)
Cache the prepared statement if it does not already exist.
|
java.sql.PreparedStatement |
getCached(StatementKey statementKey)
Retrieves a cached prepared statement if one exists.
|
private final java.util.LinkedHashMap<StatementKey,java.sql.PreparedStatement> statements
public JDBCStatementCache(int maxSize)
maxSize
- maximum number of statements in the cachejava.lang.IllegalArgumentException
- if maxSize
is less than onepublic java.sql.PreparedStatement getCached(StatementKey statementKey)
statementKey
- key for the prepared statement to look upnull
otherwise.public boolean cacheStatement(StatementKey statementKey, java.sql.PreparedStatement ps)
statementKey
- key to insert prepared statement withps
- prepared statement to cachetrue
if added to the cache, false
if
not.Apache Derby V10.13 Internals - Copyright © 2004,2016 The Apache Software Foundation. All Rights Reserved.