PG shared_buffer性能检测

select * from

  (SELECT relname, heap_blks_read, heap_blks_hit,

         round(heap_blks_hit::numeric/(heap_blks_hit + heap_blks_read), 3)

  FROM   pg_statio_user_tables

 ) as one  WHERE  heap_blks_read > 0  and relname not like '%bak%' and round<0.9 and round>0

  ORDER  BY relname  ;

很多资料说这个缓存命中率不可低于99%,如果低于了99%，表明，cache效率太低了，需要增大shared buffer。总之了，当你的shared buffer命中率太低，比如60%，基本就需要检查下你配置的shared buffers是否太小了，导致你cache利用率如此之低。

相关连接：https://my.oschina.net/u/2381678/blog/601681