PostgreSQL 對 fsync() 的行為傷腦筋...

摘要： FOSDEM 2019 上的演講，討論PostgreSQL 在確保ACID 特性中的Durability 時遇到fsync() 的行為跟預想的不一樣 (主要是當fsync() 失敗的行為)：「PostgreSQL vs. fsync 」...

FOSDEM 2019 上的演講，討論PostgreSQL 在確保ACID 特性中的Durability 時遇到fsync() 的行為跟預想的不一樣 (主要是當fsync() 失敗的行為)：「PostgreSQL vs. fsync 」。

在「PostgreSQL vs. fsync. How is it possible that PostgreSQL used fsync incorrectly for 20 years, and what we'll do about it. 」這邊的 Q&A 形式的訪談有快速描述了短期的計畫與長期的想法：

The short-term solution is ensuring that we detect fsync errors reliably at least on sufficiently recent kernels (since 4.13). On older kernels we can’t do much better, unfortunately.
The long-term solution is still being discussed in the community, but it’s hard to say how we could keep relying on buffered I/O in the future. So we may end up with direct I/O, but that’s a pretty significant change and is likely going to be a multi-year project.

在MySQL 這邊則是以O_DIRECT 為主的世界，受到的影響就小很多了...