Java RocksDB安装与应用
rocksdb 是一个可嵌入的,持久性的 key-value存储。
以下介绍来自rocksdb 中文官网
https://rocksdb.org.cn/
它有以下四个特点
1 高性能:rocksdb使用一套日志结构的数据库引擎,为了更好的性能,这套引擎是用c++编写的。 key和value是任意大小的字节流。
2 为快速存储而优化:rocksdb为快速而又低延迟的存储设备(例如闪存或者高速硬盘)而特殊优化处理。 rocksdb将最大限度的发挥闪存和ram的高度率读写性能。
3 可适配性 :rocksdb适合于多种不同工作量类型。 从像myrocks这样的数据存储引擎, 到应用数据缓存, 甚至是一些嵌入式工作量,rocksdb都可以从容面对这些不同的数据工作量需求。
4 基础和高级的数据库操作 rocksdb提供了一些基础的操作,例如打开和关闭数据库。 对于合并和压缩过滤等高级操作,也提供了读写支持。
rockdb 安装与使用
rocksdb 安装有多种方式。由于官方没有提供对应平台的二进制库,所以需要自己编译使用。
rocksdb 的安装很简单,但是需要转变一下对于rocksdb 的看法。它不是一个重量级别的数据库,是一个嵌入式的key-value 存储。这意味着你只要在你的maven项目中添加 rocksdb的依赖,就可以在开发环境中自我尝试了。如果你没有理解这点,你就可能会走入下面这两种不推荐的安装方式。
方式 一 去查看rocksdb 的官网 发现要写 一个c++ 程序(不推荐)
#include <assert> #include "rocksdb/db.h" rocksdb::db* db; rocksdb::options options; options.create_if_missing = true; rocksdb::status status = rocksdb::db::open(options, "/tmp/testdb", &db); assert(status.ok());
创建一个数据库???? 怎么和之前用的mysql 或者mongo 不一样,为啥没有一个start.sh 或者start.bat 之类的脚本。难道要我写。写完了编译发现还不知道怎么和rocksdb 库进行关联,怎么办,我c++都忘完了。
方式二 使用pyrocksdb (不推荐)
http://pyrocksdb.readthedocs.io/en/latest/installation.html
详细的安装文档见pyrocksdb 的官网安装文档。
以上两种方式对于熟悉c++ 或者python 的开发者来说都比较友好,但对于java 开发者来说不是太友好。
接下来就介绍第三种方式。
方式三 使用maven (推荐)
新建maven 项目,修改pom.xml 依赖里面添加
<dependency> <groupid>org.rocksdb</groupid> <artifactid>rocksdbjni</artifactid> <version>5.8.6</version> </dependency>
可以选择你喜欢的版本。
然后更高maven 的语言级别,我这里全局设置为了1.8
<profiles> <profile> <id>jdk18</id> <activation> <activebydefault>true</activebydefault> <jdk>1.8</jdk> </activation> <properties> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.compilerversion>1.8</maven.compiler.compilerversion> </properties> </profile> </profiles>
到这里,环境就装好了,是不是又回到了熟悉的java 世界。
然后copy 源码包下的一个类,在ide中修改一下运行配置,加一个程序运行中数据库存储路径,就可以运行测试了 。我会在文章最后给出这个类。
运行控制台会有日志输出,同时也文件中也会出现一下新的文件。
后面会更新更多关于rockdb 开发api 的介绍,以及在生产中的应用,希望大家关注。
// copyright (c) 2011-present, facebook, inc. all rights reserved. // this source code is licensed under both the gplv2 (found in the // copying file in the root directory) and apache 2.0 license // (found in the license.apache file in the root directory). import org.rocksdb.*; import org.rocksdb.util.sizeunit; import java.util.arraylist; import java.util.arrays; import java.util.list; import java.util.map; public class rocksdbsample { static { rocksdb.loadlibrary(); } public static void main(final string[] args) { if (args.length < 1) { system.out.println("usage: rocksdbsample db_path"); system.exit(-1); } final string db_path = args[0]; final string db_path_not_found = db_path + "_not_found"; system.out.println("rocksdbsample"); try (final options options = new options(); final filter bloomfilter = new bloomfilter(10); final readoptions readoptions = new readoptions() .setfillcache(false); final statistics stats = new statistics(); final ratelimiter ratelimiter = new ratelimiter(10000000,10000, 10)) { try (final rocksdb db = rocksdb.open(options, db_path_not_found)) { assert (false); } catch (final rocksdbexception e) { system.out.format("caught the expected exception -- %s\n", e); } try { options.setcreateifmissing(true) .setstatistics(stats) .setwritebuffersize(8 * sizeunit.kb) .setmaxwritebuffernumber(3) .setmaxbackgroundcompactions(10) .setcompressiontype(compressiontype.snappy_compression) .setcompactionstyle(compactionstyle.universal); } catch (final illegalargumentexception e) { assert (false); } assert (options.createifmissing() == true); assert (options.writebuffersize() == 8 * sizeunit.kb); assert (options.maxwritebuffernumber() == 3); assert (options.maxbackgroundcompactions() == 10); assert (options.compressiontype() == compressiontype.snappy_compression); assert (options.compactionstyle() == compactionstyle.universal); assert (options.memtablefactoryname().equals("skiplistfactory")); options.setmemtableconfig( new hashskiplistmemtableconfig() .setheight(4) .setbranchingfactor(4) .setbucketcount(2000000)); assert (options.memtablefactoryname().equals("hashskiplistrepfactory")); options.setmemtableconfig( new hashlinkedlistmemtableconfig() .setbucketcount(100000)); assert (options.memtablefactoryname().equals("hashlinkedlistrepfactory")); options.setmemtableconfig( new vectormemtableconfig().setreservedsize(10000)); assert (options.memtablefactoryname().equals("vectorrepfactory")); options.setmemtableconfig(new skiplistmemtableconfig()); assert (options.memtablefactoryname().equals("skiplistfactory")); options.settableformatconfig(new plaintableconfig()); // plain-table requires mmap read options.setallowmmapreads(true); assert (options.tablefactoryname().equals("plaintable")); options.setratelimiter(ratelimiter); final blockbasedtableconfig table_options = new blockbasedtableconfig(); table_options.setblockcachesize(64 * sizeunit.kb) .setfilter(bloomfilter) .setcachenumshardbits(6) .setblocksizedeviation(5) .setblockrestartinterval(10) .setcacheindexandfilterblocks(true) .sethashindexallowcollision(false) .setblockcachecompressedsize(64 * sizeunit.kb) .setblockcachecompressednumshardbits(10); assert (table_options.blockcachesize() == 64 * sizeunit.kb); assert (table_options.cachenumshardbits() == 6); assert (table_options.blocksizedeviation() == 5); assert (table_options.blockrestartinterval() == 10); assert (table_options.cacheindexandfilterblocks() == true); assert (table_options.hashindexallowcollision() == false); assert (table_options.blockcachecompressedsize() == 64 * sizeunit.kb); assert (table_options.blockcachecompressednumshardbits() == 10); options.settableformatconfig(table_options); assert (options.tablefactoryname().equals("blockbasedtable")); try (final rocksdb db = rocksdb.open(options, db_path)) { db.put("hello".getbytes(), "world".getbytes()); final byte[] value = db.get("hello".getbytes()); assert ("world".equals(new string(value))); final string str = db.getproperty("rocksdb.stats"); assert (str != null && !str.equals("")); } catch (final rocksdbexception e) { system.out.format("[error] caught the unexpected exception -- %s\n", e); assert (false); } try (final rocksdb db = rocksdb.open(options, db_path)) { db.put("hello".getbytes(), "world".getbytes()); byte[] value = db.get("hello".getbytes()); system.out.format("get('hello') = %s\n", new string(value)); for (int i = 1; i <= 9; ++i) { for (int j = 1; j <= 9; ++j) { db.put(string.format("%dx%d", i, j).getbytes(), string.format("%d", i * j).getbytes()); } } for (int i = 1; i <= 9; ++i) { for (int j = 1; j <= 9; ++j) { system.out.format("%s ", new string(db.get( string.format("%dx%d", i, j).getbytes()))); } system.out.println(""); } // write batch test try (final writeoptions writeopt = new writeoptions()) { for (int i = 10; i <= 19; ++i) { try (final writebatch batch = new writebatch()) { for (int j = 10; j <= 19; ++j) { batch.put(string.format("%dx%d", i, j).getbytes(), string.format("%d", i * j).getbytes()); } db.write(writeopt, batch); } } } for (int i = 10; i <= 19; ++i) { for (int j = 10; j <= 19; ++j) { assert (new string( db.get(string.format("%dx%d", i, j).getbytes())).equals( string.format("%d", i * j))); system.out.format("%s ", new string(db.get( string.format("%dx%d", i, j).getbytes()))); } system.out.println(""); } value = db.get("1x1".getbytes()); assert (value != null); value = db.get("world".getbytes()); assert (value == null); value = db.get(readoptions, "world".getbytes()); assert (value == null); final byte[] testkey = "asdf".getbytes(); final byte[] testvalue = "asdfghjkl;'?><mnbvcxzqwertyuiop{+_)(*&^%$#@".getbytes(); db.put(testkey, testvalue); byte[] testresult = db.get(testkey); assert (testresult != null); assert (arrays.equals(testvalue, testresult)); assert (new string(testvalue).equals(new string(testresult))); testresult = db.get(readoptions, testkey); assert (testresult != null); assert (arrays.equals(testvalue, testresult)); assert (new string(testvalue).equals(new string(testresult))); final byte[] insufficientarray = new byte[10]; final byte[] enougharray = new byte[50]; int len; len = db.get(testkey, insufficientarray); assert (len > insufficientarray.length); len = db.get("asdfjkl;".getbytes(), enougharray); assert (len == rocksdb.not_found); len = db.get(testkey, enougharray); assert (len == testvalue.length); len = db.get(readoptions, testkey, insufficientarray); assert (len > insufficientarray.length); len = db.get(readoptions, "asdfjkl;".getbytes(), enougharray); assert (len == rocksdb.not_found); len = db.get(readoptions, testkey, enougharray); assert (len == testvalue.length); db.remove(testkey); len = db.get(testkey, enougharray); assert (len == rocksdb.not_found); // repeat the test with writeoptions try (final writeoptions writeopts = new writeoptions()) { writeopts.setsync(true); writeopts.setdisablewal(true); db.put(writeopts, testkey, testvalue); len = db.get(testkey, enougharray); assert (len == testvalue.length); assert (new string(testvalue).equals( new string(enougharray, 0, len))); } try { for (final tickertype statstype : tickertype.values()) { if (statstype != tickertype.ticker_enum_max) { stats.gettickercount(statstype); } } system.out.println("gettickercount() passed."); } catch (final exception e) { system.out.println("failed in call to gettickercount()"); assert (false); //should never reach here. } try { for (final histogramtype histogramtype : histogramtype.values()) { if (histogramtype != histogramtype.histogram_enum_max) { histogramdata data = stats.gethistogramdata(histogramtype); } } system.out.println("gethistogramdata() passed."); } catch (final exception e) { system.out.println("failed in call to gethistogramdata()"); assert (false); //should never reach here. } try (final rocksiterator iterator = db.newiterator()) { boolean seektofirstpassed = false; for (iterator.seektofirst(); iterator.isvalid(); iterator.next()) { iterator.status(); assert (iterator.key() != null); assert (iterator.value() != null); seektofirstpassed = true; } if (seektofirstpassed) { system.out.println("iterator seektofirst tests passed."); } boolean seektolastpassed = false; for (iterator.seektolast(); iterator.isvalid(); iterator.prev()) { iterator.status(); assert (iterator.key() != null); assert (iterator.value() != null); seektolastpassed = true; } if (seektolastpassed) { system.out.println("iterator seektolastpassed tests passed."); } iterator.seektofirst(); iterator.seek(iterator.key()); assert (iterator.key() != null); assert (iterator.value() != null); system.out.println("iterator seek test passed."); } system.out.println("iterator tests passed."); final list<byte[]> keys = new arraylist<>(); try (final rocksiterator iterator = db.newiterator()) { for (iterator.seektolast(); iterator.isvalid(); iterator.prev()) { keys.add(iterator.key()); } } map<byte[], byte[]> values = db.multiget(keys); assert (values.size() == keys.size()); for (final byte[] value1 : values.values()) { assert (value1 != null); } values = db.multiget(new readoptions(), keys); assert (values.size() == keys.size()); for (final byte[] value1 : values.values()) { assert (value1 != null); } } catch (final rocksdbexception e) { system.err.println(e); } } } }
以上就是本次给大家介绍的java中rocksdb安装与应用的全部内容,如果大家在学习后还有任何不明白的可以在下方的留言区域讨论,感谢对的支持。
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