小编Joe*_*ber的帖子

我在Spanner中有以下查询优化问题,并希望有一个我缺少的技巧,这将帮助我将查询规划器弯曲到我的意愿.

这是简化的架构:

create table T0 (
  key0  int64 not null,
  value int64,
  other int64 not null,
) primary key (key0);

create table T1 {
  key1  int64 not null,
  other int64 not null
} primary key (key1);

并在IN子句中使用子查询进行查询:

select value from T0 t0
where t0.other in (
  select t1.other from T1 t1 where t1.key1 in (42, 43, 44)  -- note: this subquery is a good deal more complex than this
)

通过T0的散列连接与子查询的输出生成10个元素集:

Operator                     Rows  Executions
-----------------------      ----- ----------
Serialize …