digoal
2021-06-15
PostgreSQL , pHOT
增强HOT , 降低索引更新需求.
当前HOT仅限于索引字段未更新, 同时tuple new version没有插入新block的场景. 只要涉及一个索引改动, 所有索引都要改.
《PostgreSQL Heap Only Tuple - HOT (降低UPDATE引入的索引写IO放大)》
增强的叫phot, 没有修改value的column对应的索引不需要更新, 从而降低索引更新量.
https://commitfest.postgresql.org/33/2981/
https://www.postgresql.org/message-id/flat/2ECBBCA0-4D8D-4841-8872-4A5BBDC063D2@amazon.com
Hello,
I'm hoping to gather some early feedback on a heap optimization I've
been working on. In short, I'm hoping to add "partial heap only
tuple" (PHOT) support, which would allow you to skip updating indexes
for unchanged columns even when other indexes require updates. Today,
HOT works wonders when no indexed columns are updated.
您的愿望将传达给PG kernel hacker、数据库厂商等, 帮助提高数据库产品质量和功能, 说不定下一个PG版本就有您提出的功能点. 针对非常好的提议，奖励限量版PG文化衫、纪念品、贴纸、PG热门书籍等，奖品丰富，快来许愿。开不开森.
