[英]Postgres query on very large table with indexes still very slow
尽管mytable在recdate
上被索引(mytable具有> 60 M记录),但以下查询的运行非常缓慢,查询几乎花费了7分钟。
select to_char(recdate, 'yyyy'), count(*)
from mytable
group by to_char(recdate, 'yyyy')
您没有提供执行计划,但我想基于函数的索引将涵盖
CREATE INDEX mytable_idx ON mytable( to_char(recdate,'yyyy'));
查询:
select to_char(recdate,'yyyy'),count(*)
from mytable
group by to_char(recdate,'yyyy')
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