特性	LevelDB	关系型数据库（如 MySQL）
数据模型	键值存储（Key-Value）	关系模型（表、行、列）
写入性能	⭐⭐⭐⭐⭐（顺序写入优化）	⭐⭐（需维护索引和事务日志）
读取性能	⭐⭐⭐⭐（按键查询极快）	⭐⭐⭐（支持索引优化复杂查询）
复杂查询	❌ 仅支持键或简单范围查询	⭐⭐⭐⭐⭐（支持 SQL 复杂逻辑）
事务支持	❌ 单操作原子性，无跨记录事务	⭐⭐⭐⭐（ACID 事务）
扩展性	❌ 单机存储，需手动分片	⭐⭐⭐（支持主从复制、分库分表）
数据一致性	⭐⭐（最终一致性）	⭐⭐⭐⭐（强一致性）
维护复杂度	⭐⭐（无内置备份工具，需手动管理）	⭐⭐⭐（成熟工具支持备份、监控）
适用场景	日志、时序数据、简单流水记录	复杂业务系统、需关联查询的场景

架构

levelDB架构图

leveldb中主要由以下几个重要的部件构成：

memtable
immutable memtable
log(journal)
sstable
manifest
current

实践

使用levelDB在ubuntu server上部署一个博客图床，Nginx+Java SpringBoot+levelDB

架构图

用户端 (HTTPS)
       ↓
[Nginx (SSL 终止、反向代理、静态文件服务)]
       ↓
[Spring Boot (上传接口、元数据管理)]
       ↓
[LevelDB (元数据存储) + 文件系统 (图片存储)]

部署levelDB

安装依赖

1 2	sudo apt update sudo apt install -y build-essential cmake libsnappy-dev git

克隆并编译levelDB源码

git clone --recurse-submodules https://github.com/google/leveldb.git
cd leveldb
mkdir -p build && cd build
cmake -DCMAKE_BUILD_TYPE=Release .. && cmake --build .

编译完成后，库文件会生成在build目录下。

出现如下报错，大概是这个版本不稳定，可以下载release源码，并且将第三方组件googletest和benchmark的源码下载，并放入对应的third_party目录下。

In file included from /home/yankf/prj/leveldb/util/comparator.cc:14:
/home/yankf/prj/leveldb/./util/no_destructor.h: In constructor ‘leveldb::NoDestructor<InstanceType>::NoDestructor(ConstructorArgTypes&& ...)’:
/home/yankf/prj/leveldb/./util/no_destructor.h:24:24: error: ‘is_standard_layout_v’ is not a member of ‘std’; did you mean ‘is_standard_layout’?
   24 |     static_assert(std::is_standard_layout_v<NoDestructor<InstanceType>>);
      |                        ^~~~~~~~~~~~~~~~~~~~
      |                        is_standard_layout
/home/yankf/prj/leveldb/./util/no_destructor.h:24:70: error: expected primary-expression before ‘>’ token
   24 |     static_assert(std::is_standard_layout_v<NoDestructor<InstanceType>>);
      |                                                                      ^~
/home/yankf/prj/leveldb/./util/no_destructor.h:24:72: error: expected primary-expression before ‘)’ token
   24 |     static_assert(std::is_standard_layout_v<NoDestructor<InstanceType>>);
      |                                                                        ^
gmake[2]: *** [CMakeFiles/leveldb.dir/build.make:468: CMakeFiles/leveldb.dir/util/comparator.cc.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:181: CMakeFiles/leveldb.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2

之后再重新构建


-- The C compiler identification is GNU 13.3.0
-- The CXX compiler identification is GNU 13.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for unistd.h
-- Looking for unistd.h - found
-- Looking for crc32c_value in crc32c
-- Looking for crc32c_value in crc32c - not found
-- Looking for snappy_compress in snappy
-- Looking for snappy_compress in snappy - found
-- Looking for malloc in tcmalloc
-- Looking for malloc in tcmalloc - not found
-- Looking for fdatasync
-- Looking for fdatasync - found
-- Looking for F_FULLFSYNC
-- Looking for F_FULLFSYNC - not found
-- Looking for O_CLOEXEC
-- Looking for O_CLOEXEC - found
-- Performing Test HAVE_CLANG_THREAD_SAFETY
-- Performing Test HAVE_CLANG_THREAD_SAFETY - Failed
-- Performing Test LEVELDB_HAVE_NO_MISSING_FIELD_INITIALIZERS
-- Performing Test LEVELDB_HAVE_NO_MISSING_FIELD_INITIALIZERS - Success
-- Performing Test HAVE_CXX17_HAS_INCLUDE
-- Performing Test HAVE_CXX17_HAS_INCLUDE - Success
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE
-- Failed to find LLVM FileCheck
-- Found Git: /usr/bin/git (found version "2.43.0")
-- Google Benchmark version: v1.9.1, normalized to 1.9.1
-- Looking for shm_open in rt
-- Looking for shm_open in rt - found
-- Performing Test HAVE_CXX_FLAG_WALL
-- Performing Test HAVE_CXX_FLAG_WALL - Success
-- Performing Test HAVE_CXX_FLAG_WEXTRA
-- Performing Test HAVE_CXX_FLAG_WEXTRA - Success
-- Performing Test HAVE_CXX_FLAG_WSHADOW
-- Performing Test HAVE_CXX_FLAG_WSHADOW - Success
-- Performing Test HAVE_CXX_FLAG_WFLOAT_EQUAL
-- Performing Test HAVE_CXX_FLAG_WFLOAT_EQUAL - Success
-- Performing Test HAVE_CXX_FLAG_WOLD_STYLE_CAST
-- Performing Test HAVE_CXX_FLAG_WOLD_STYLE_CAST - Success
-- Performing Test HAVE_CXX_FLAG_WCONVERSION
-- Performing Test HAVE_CXX_FLAG_WCONVERSION - Success
-- Performing Test HAVE_CXX_FLAG_WERROR
-- Performing Test HAVE_CXX_FLAG_WERROR - Success
-- Performing Test HAVE_CXX_FLAG_WSUGGEST_OVERRIDE
-- Performing Test HAVE_CXX_FLAG_WSUGGEST_OVERRIDE - Success
-- Performing Test HAVE_CXX_FLAG_PEDANTIC
-- Performing Test HAVE_CXX_FLAG_PEDANTIC - Success
-- Performing Test HAVE_CXX_FLAG_PEDANTIC_ERRORS
-- Performing Test HAVE_CXX_FLAG_PEDANTIC_ERRORS - Success
-- Performing Test HAVE_CXX_FLAG_WSHORTEN_64_TO_32
-- Performing Test HAVE_CXX_FLAG_WSHORTEN_64_TO_32 - Failed
-- Performing Test HAVE_CXX_FLAG_FSTRICT_ALIASING
-- Performing Test HAVE_CXX_FLAG_FSTRICT_ALIASING - Success
-- Performing Test HAVE_CXX_FLAG_WNO_DEPRECATED_DECLARATIONS
-- Performing Test HAVE_CXX_FLAG_WNO_DEPRECATED_DECLARATIONS - Success
-- Performing Test HAVE_CXX_FLAG_WNO_DEPRECATED
-- Performing Test HAVE_CXX_FLAG_WNO_DEPRECATED - Success
-- Performing Test HAVE_CXX_FLAG_FNO_EXCEPTIONS
-- Performing Test HAVE_CXX_FLAG_FNO_EXCEPTIONS - Success
-- Performing Test HAVE_CXX_FLAG_WSTRICT_ALIASING
-- Performing Test HAVE_CXX_FLAG_WSTRICT_ALIASING - Success
-- Performing Test HAVE_CXX_FLAG_WD654
-- Performing Test HAVE_CXX_FLAG_WD654 - Failed
-- Performing Test HAVE_CXX_FLAG_WTHREAD_SAFETY
-- Performing Test HAVE_CXX_FLAG_WTHREAD_SAFETY - Failed
-- Performing Test HAVE_CXX_FLAG_COVERAGE
-- Performing Test HAVE_CXX_FLAG_COVERAGE - Success
-- Compiling and running to test HAVE_STD_REGEX
-- Performing Test HAVE_STD_REGEX -- success
-- Compiling and running to test HAVE_GNU_POSIX_REGEX
-- Performing Test HAVE_GNU_POSIX_REGEX -- failed to compile
-- Compiling and running to test HAVE_POSIX_REGEX
-- Performing Test HAVE_POSIX_REGEX -- success
-- Compiling and running to test HAVE_STEADY_CLOCK
-- Performing Test HAVE_STEADY_CLOCK -- success
-- Compiling and running to test HAVE_PTHREAD_AFFINITY
-- Performing Test HAVE_PTHREAD_AFFINITY -- success
-- Looking for sqlite3_open in sqlite3
-- Looking for sqlite3_open in sqlite3 - not found
-- Performing Test HAVE_KYOTOCABINET
-- Performing Test HAVE_KYOTOCABINET - Failed
-- Configuring done (3.5s)
-- Generating done (0.0s)
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安装LevelDB系统库（可选）

1
2
3

sudo cp -r ../include/leveldb /usr/local/include/
sudo cp ./libleveldb.* /usr/local/lib/
sudo ldconfig  # 更新动态链接库缓存

两种访问方式的对比

方案	优点	缺点	适用场景
通过 Spring Boot 服务	1. 支持动态处理（如权限验证、水印） 2. 统一接口管理	1. 性能较低（需经过 Java 应用层） 2. 增加服务负载	需动态处理图片的场景
通过 Nginx 直接访问	1. 高性能（静态文件直读） 2. 减少应用层压力	1. 无法动态控制访问权限	纯静态资源分发（无需鉴权）

将服务部署到ubuntu

windows本地测试可以使用如下语句

1	java -jar .\spring-research-0.0.1-SNAPSHOT.jar -Dspring.profiles.active=main -Dserver.port=9003 -Dfile.encoding=UTF-8 -verbose:gc -XX:+PrintGCDetails

Gradle打包出jar包，传输到ubuntu环境。

1	nohup java -jar spring-research-0.0.1-SNAPSHOT.jar -Dspring.profiles.active=main -Dserver.port=9003 -Dfile.encoding=UTF-8 -verbose:gc -XX:+PrintGCDetails > springboot.log 2>&1 &

使用该语句验证，注意图片是否已经存在

1	curl -X POST -F "file=@./fault.jpg" http://localhost:9003/upload