MapDB 0.9.1 发布，紧急 Bug 修复版本_Linux系统运维 - 专业的linux运维学习与交流社区

MapDB 0.9.1 发布了，MapDB 提供了并发的 TreeMap 和 HashMap ，使用基于磁盘的存储。快速、可伸缩性以及易用。

0.9.1 版本修复了首个 0.9.0 版本中一些非常紧急的 bug，包括：

Open issues:

Issue #119 - BTreeMap (TreeMap) may not release all locks and consequently crash. This is unconfirmed and hard to replicate concurrent bug. I temporarily added assertion which slows down BTreeMap updates, but helps to diagnose this problem
Issue #118 - StoreWAL fails to create log for unknown reasons and crashes. Not reproduced yet, need to investigate.

Changes:

FIX #111 - Compaction fails with large data sets
FIX - BTreeKeySerializer.ZERO_OR_POSITIVE_INT was broken
FIX #89 - StoreAppend reopen failed
FIX #112 - Compaction fails with WAL enabled
FIX #114 - RandomAccessFile fails with WAL
FIX #113 - MemoryMappedFile was not unlocked on Windows after DB close
FIX - rewrite AsynwWriteEngine, fix many concurrent bugs
FIX - Files were not synced on DB.close(). Possible data loss.
FIX - free space reuse did not worked in StoreDirect and StoreWAL. Storage file grown infinitely with each update.
FIX #116 - HTreeMap.isEmpty returned wrong result.
FIX #121 - WAL could get corrupted in some cases.
ADD - basic benchmark
ADD - error message if file rename fails after compaction finishes
ADD - #119 BTreeMap locking could not be fixed, I added assertion to help diagnose issue. Small performance drop on BTreeMap updates.
ADD - performance improvement if Snapshot engine is not used.

下载地址：mapdb-0.9.1

MapDB 提供了并发的 TreeMap 和 HashMap ，使用基于磁盘的存储。快速、可伸缩性以及易用。

示例代码：

				
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								import org.mapdb.*;
						
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								// configure and open database using builder pattern.
						
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								// all options are available with code auto-completion.
						
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								DB db = DBMaker.newFileDB(new File("testdb"))
						
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								               .closeOnJvmShutdown()
						
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								               .encryptionEnable("password")
						
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								               .make();
						
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								// open existing an collection (or create new)
						
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								ConcurrentNavigableMap<Integer,String> map = db.getTreeMap("collectionName");
						
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								map.put(1, "one");
						
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								map.put(2, "two");
						
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								// map.keySet() is now [1,2]
						
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								db.commit();  //persist changes into disk
						
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								map.put(3, "three");
						
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								// map.keySet() is now [1,2,3]
						
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								db.rollback(); //revert recent changes
						
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								// map.keySet() is now [1,2]
						
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								db.close();

jankotek / MapDB

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MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine. — More...

http://www.mapdb.org

Issues
#92	MapDB should implement Redis API	by jankotek 2013-05-06
#130	ArrayIndexOutOfBoundsException when calling clear() on empty Map	by thmarx 2013-05-06
#93	Store without Index File	by jankotek 2013-04-27
#123	Slow: DBMaker.randomAccessFileEnable() / RAF	by ggrandes 2013-04-26
#96	Graph API	by jankotek 2013-04-23

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