• Home
  • History
  • Annotate
  • Line#
  • Navigate
  • Raw
  • Download
  • only in /netgear-WNDR4500v2-V1.0.0.60_1.0.38/ap/gpl/timemachine/db-4.7.25.NC/java/src/com/sleepycat/db/
1/*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 2002,2008 Oracle.  All rights reserved.
5 *
6 * $Id: SecondaryDatabase.java,v 12.7 2008/01/17 05:04:53 mjc Exp $
7 */
8
9package com.sleepycat.db;
10
11import com.sleepycat.db.internal.Db;
12import com.sleepycat.db.internal.DbConstants;
13
14/**
15A secondary database handle.
16<p>
17Secondary databases are opened with {@link
18Environment#openSecondaryDatabase Environment.openSecondaryDatabase} and are
19always associated with a single primary database.  The distinguishing
20characteristics of a secondary database are:
21<ul>
22<li>Records are automatically added to a secondary database when records are
23added, modified and deleted in the primary database.  Direct calls to
24<code>put()</code> methods on a secondary database are prohibited.</li>
25<li>The {@link #delete delete} method of a secondary database will delete
26the primary record and as well as all its associated secondary records.</li>
27<li>Calls to all <code>get()</code> methods will return the data from the
28associated primary database.</li>
29<li>Additional <code>get()</code> method signatures are provided to return
30the primary key in an additional <code>pKey</code> parameter.</li>
31<li>Calls to {@link #openCursor openCursor} will return a {@link
32SecondaryCursor}, which itself has <code>get()</code> methods that return
33the data of the primary database and additional <code>get()</code> method
34signatures for returning the primary key.</li>
35<li>The {@link #openSecondaryCursor openSecondaryCursor} method is provided
36to return a {@link SecondaryCursor} that doesn't require casting.</li>
37</ul>
38<p>
39Before opening or creating a secondary database you must implement the {@link
40SecondaryKeyCreator}
41interface.
42<p>
43For example, to create a secondary database that supports duplicates:
44<pre>
45    Database primaryDb; // The primary database must already be open.
46    SecondaryKeyCreator keyCreator; // Your key creator implementation.
47    SecondaryConfig secConfig = new SecondaryConfig();
48    secConfig.setAllowCreate(true);
49    secConfig.setSortedDuplicates(true);
50    secConfig.setKeyCreator(keyCreator);
51    SecondaryDatabase newDb = env.openSecondaryDatabase(transaction,
52                                                        "myDatabaseName",
53                                                        primaryDb,
54                                                        secConfig)
55</pre>
56<p>
57If a primary database is to be associated with one or more secondary
58databases, it may not be configured for duplicates.
59<p>
60Note that the associations between primary and secondary databases are not
61stored persistently.  Whenever a primary database is opened for write access by
62the application, the appropriate associated secondary databases should also be
63opened by the application.  This is necessary to ensure data integrity when
64changes are made to the primary database.
65*/
66public class SecondaryDatabase extends Database {
67    private final Database primaryDatabase;
68
69    /* package */
70    SecondaryDatabase(final Db db, final Database primaryDatabase)
71        throws DatabaseException {
72
73        super(db);
74        this.primaryDatabase = primaryDatabase;
75    }
76
77    /**
78    Open a database.
79<p>
80The database is represented by the file and database parameters.
81<p>
82The currently supported database file formats (or <em>access
83methods</em>) are Btree, Hash, Queue, and Recno.  The Btree format is a
84representation of a sorted, balanced tree structure.  The Hash format
85is an extensible, dynamic hashing scheme.  The Queue format supports
86fast access to fixed-length records accessed sequentially or by logical
87record number.  The Recno format supports fixed- or variable-length
88records, accessed sequentially or by logical record number, and
89optionally backed by a flat text file.
90<p>
91Storage and retrieval are based on key/data pairs; see {@link com.sleepycat.db.DatabaseEntry DatabaseEntry}
92for more information.
93<p>
94Opening a database is a relatively expensive operation, and maintaining
95a set of open databases will normally be preferable to repeatedly
96opening and closing the database for each new query.
97<p>
98In-memory databases never intended to be preserved on disk may be
99created by setting both the fileName and databaseName parameters to
100null.  Note that in-memory databases can only ever be shared by sharing
101the single database handle that created them, in circumstances where
102doing so is safe.  The environment variable <code>TMPDIR</code> may
103be used as a directory in which to create temporary backing files.
104<p>
105@param fileName
106The name of an underlying file that will be used to back the database.
107On Windows platforms, this argument will be interpreted as a UTF-8
108string, which is equivalent to ASCII for Latin characters.
109<p>
110@param databaseName
111An optional parameter that allows applications to have multiple
112databases in a single file.  Although no databaseName parameter needs
113to be specified, it is an error to attempt to open a second database in
114a physical file that was not initially created using a databaseName
115parameter.  Further, the databaseName parameter is not supported by the
116Queue format.
117<p>
118@param primaryDatabase
119a database handle for the primary database that is to be indexed.
120<p>
121@param config The secondary database open attributes.  If null, default attributes are used.
122    */
123    public SecondaryDatabase(final String fileName,
124                             final String databaseName,
125                             final Database primaryDatabase,
126                             final SecondaryConfig config)
127        throws DatabaseException, java.io.FileNotFoundException {
128
129        this(SecondaryConfig.checkNull(config).openSecondaryDatabase(
130                null, null, fileName, databaseName, primaryDatabase.db),
131            primaryDatabase);
132    }
133
134    /** {@inheritDoc} */
135    public Cursor openCursor(final Transaction txn, final CursorConfig config)
136        throws DatabaseException {
137
138        return openSecondaryCursor(txn, config);
139    }
140
141    /**
142    Obtain a cursor on a database, returning a <code>SecondaryCursor</code>.
143    Calling this method is the equivalent of calling {@link #openCursor} and
144    casting the result to {@link SecondaryCursor}.
145    <p>
146    @param txn
147    To use a cursor for writing to a transactional database, an explicit
148    transaction must be specified.  For read-only access to a transactional
149    database, the transaction may be null.  For a non-transactional database,
150    the transaction must be null.
151    <p>
152    To transaction-protect cursor operations, cursors must be opened and closed
153    within the context of a transaction, and the txn parameter specifies the
154    transaction context in which the cursor will be used.
155    <p>
156    @param config
157    The cursor attributes.  If null, default attributes are used.
158    <p>
159    @return
160    A secondary database cursor.
161    <p>
162    @throws DatabaseException if a failure occurs.
163    */
164    public SecondaryCursor openSecondaryCursor(final Transaction txn,
165                                               final CursorConfig config)
166        throws DatabaseException {
167
168        return new SecondaryCursor(this,
169            CursorConfig.checkNull(config).openCursor(db,
170                (txn == null) ? null : txn.txn), config);
171    }
172
173    /**
174    Returns the primary database associated with this secondary database.
175    <p>
176    @return the primary database associated with this secondary database.
177    */
178    public Database getPrimaryDatabase() {
179        return primaryDatabase;
180    }
181
182    /** {@inheritDoc} */
183    public DatabaseConfig getConfig()
184        throws DatabaseException {
185
186        return getSecondaryConfig();
187    }
188
189    /**
190    Returns a copy of the secondary configuration of this database.
191    <p>
192    @return a copy of the secondary configuration of this database.
193    <p>
194    <p>
195@throws DatabaseException if a failure occurs.
196    */
197    public SecondaryConfig getSecondaryConfig()
198        throws DatabaseException {
199
200        return new SecondaryConfig(db);
201    }
202
203    /**
204    Retrieves the key/data pair with the given key.  If the matching key has
205duplicate values, the first data item in the set of duplicates is returned.
206Retrieval of duplicates requires the use of {@link Cursor} operations.
207<p>
208@param txn
209For a transactional database, an explicit transaction may be specified to
210transaction-protect the operation, or null may be specified to perform the
211operation without transaction protection.  For a non-transactional database,
212null must be specified.
213<p>
214@param key the secondary key
215used as input.  It must be initialized with a non-null byte array by the
216caller.
217<p>
218@param pKey the primary key
219returned as output.  Its byte array does not need to be initialized by the
220caller.
221<p>
222@param data the primary data
223returned as output.  Its byte array does not need to be initialized by the
224caller.
225<p>
226@param lockMode the locking attributes; if null, default attributes are used.
227<p>
228@return {@link com.sleepycat.db.OperationStatus#NOTFOUND OperationStatus.NOTFOUND} if no matching key/data pair is
229found; {@link com.sleepycat.db.OperationStatus#KEYEMPTY OperationStatus.KEYEMPTY} if the database is a Queue or Recno database and the specified key exists, but was never explicitly created by the application or was later deleted; otherwise, {@link com.sleepycat.db.OperationStatus#SUCCESS OperationStatus.SUCCESS}.
230<p>
231<p>
232@throws DeadlockException if the operation was selected to resolve a
233deadlock.
234<p>
235@throws IllegalArgumentException if an invalid parameter was specified.
236<p>
237@throws DatabaseException if a failure occurs.
238    */
239    public OperationStatus get(final Transaction txn,
240                               final DatabaseEntry key,
241                               final DatabaseEntry pKey,
242                               final DatabaseEntry data,
243                               final LockMode lockMode)
244        throws DatabaseException {
245
246        return OperationStatus.fromInt(
247            db.pget((txn == null) ? null : txn.txn, key, pKey, data,
248                LockMode.getFlag(lockMode) |
249                ((data == null) ? 0 : data.getMultiFlag())));
250    }
251
252    /**
253    Retrieves the key/data pair with the specified secondary and primary key, that
254is, both the primary and secondary key items must match.
255<p>
256@param txn
257For a transactional database, an explicit transaction may be specified to
258transaction-protect the operation, or null may be specified to perform the
259operation without transaction protection.  For a non-transactional database,
260null must be specified.
261@param key the secondary key
262used as input.  It must be initialized with a non-null byte array by the
263caller.
264@param pKey the primary key
265used as input.  It must be initialized with a non-null byte array by the
266caller.
267@param data the primary data
268returned as output.  Its byte array does not need to be initialized by the
269caller.
270<p>
271@param lockMode the locking attributes; if null, default attributes are used.
272<p>
273@return {@link com.sleepycat.db.OperationStatus#NOTFOUND OperationStatus.NOTFOUND} if no matching key/data pair is
274found; {@link com.sleepycat.db.OperationStatus#KEYEMPTY OperationStatus.KEYEMPTY} if the database is a Queue or Recno database and the specified key exists, but was never explicitly created by the application or was later deleted; otherwise, {@link com.sleepycat.db.OperationStatus#SUCCESS OperationStatus.SUCCESS}.
275<p>
276<p>
277@throws DeadlockException if the operation was selected to resolve a
278deadlock.
279<p>
280@throws IllegalArgumentException if an invalid parameter was specified.
281<p>
282@throws DatabaseException if a failure occurs.
283    */
284    public OperationStatus getSearchBoth(final Transaction txn,
285                                         final DatabaseEntry key,
286                                         final DatabaseEntry pKey,
287                                         final DatabaseEntry data,
288                                         final LockMode lockMode)
289        throws DatabaseException {
290
291        return OperationStatus.fromInt(
292            db.pget((txn == null) ? null : txn.txn, key, pKey, data,
293                DbConstants.DB_GET_BOTH | LockMode.getFlag(lockMode) |
294                ((data == null) ? 0 : data.getMultiFlag())));
295    }
296
297    /**
298    Retrieves the key/data pair associated with the specific numbered record of the database.
299<p>
300The data field of the specified key must be a byte array containing a
301record number, as described in {@link com.sleepycat.db.DatabaseEntry DatabaseEntry}.  This determines
302the record to be retrieved.
303<p>
304For this method to be called, the underlying database must be of type
305Btree, and it must have been configured to support record numbers.
306<p>
307If this method fails for any reason, the position of the cursor will be
308unchanged.
309@throws NullPointerException if a DatabaseEntry parameter is null or
310does not contain a required non-null byte array.
311<p>
312@throws DeadlockException if the operation was selected to resolve a
313deadlock.
314<p>
315@throws IllegalArgumentException if an invalid parameter was specified.
316<p>
317@throws DatabaseException if a failure occurs.
318<p>
319@param key the secondary key
320returned as output.  Its byte array does not need to be initialized by the
321caller.
322@param pKey the primary key
323returned as output.  Its byte array does not need to be initialized by the
324caller.
325@param data the primary data
326returned as output.  Multiple results can be retrieved by passing an object
327that is a subclass of {@link com.sleepycat.db.MultipleEntry MultipleEntry}, otherwise its byte array does not
328need to be initialized by the caller.
329@param lockMode the locking attributes; if null, default attributes are used.
330@return {@link com.sleepycat.db.OperationStatus#NOTFOUND OperationStatus.NOTFOUND} if no matching key/data pair is
331found; {@link com.sleepycat.db.OperationStatus#KEYEMPTY OperationStatus.KEYEMPTY} if the database is a Queue or Recno database and the specified key exists, but was never explicitly created by the application or was later deleted; otherwise, {@link com.sleepycat.db.OperationStatus#SUCCESS OperationStatus.SUCCESS}.
332    */
333    public OperationStatus getSearchRecordNumber(final Transaction txn,
334                                                 final DatabaseEntry key,
335                                                 final DatabaseEntry pKey,
336                                                 final DatabaseEntry data,
337                                                 final LockMode lockMode)
338        throws DatabaseException {
339
340        return OperationStatus.fromInt(
341            db.pget((txn == null) ? null : txn.txn, key, pKey, data,
342                DbConstants.DB_SET_RECNO | LockMode.getFlag(lockMode) |
343                ((data == null) ? 0 : data.getMultiFlag())));
344    }
345}
346