[RocksDB剖析系列] BlockBasedTableBuilder源码解读

参考：

• https://www.jianshu.com/p/9b5...
• https://zhuanlan.zhihu.com/p/...

SST File Format

之前在LSM-Tree部分有提过，但当时了解的比较浅

[data block 1]
[data block 2]
...
[data block N]
[meta block 1: filter block]                  
[meta block 2: index block]
[meta block 3: compression dictionary block]  
[meta block 4: range deletion block]          
[meta block 5: stats block]                   
...
[meta block K: future extended block]  (More meta blocks may be added in the future)
[metaindex block]
[Footer]                               (fixed size; starts at file_size - sizeof(Footer))

与BlockBasedTableBuilder相关的类有以下几个

• BlockBasedTable, 该类封装了用于读取磁盘BlockBasedTable类型的SST表的逻辑。
• BlockBasedTableBuilder, 该类用于在磁盘上构建一个BlockBasedTable类型的SST表。
• BlockBasedTableFactory, 该类是BlockBasedTable工厂方法的实现，用于创建BlockBasedTable/BlockBasedTableBuilder。

Write Block的顺序：

Write meta blocks, metaindex block and footer in the following order.

1. [meta block: filter]
2. [meta block: index]
3. [meta block: compression dictionary]
4. [meta block: range deletion tombstone]
5. [meta block: properties]
6. [metaindex block]
7. Footer