should be join conditions, not just
> fields.
> Check the example usage in RelMetadataTest.java#checkPredicates L1435.
>
> - Haisheng
>
> --
> 发件人：Chia-Hung Lin
> 日 期：2019年06月26日 05:38:30
> 收件人：
> 主 题：How
The input parameter of semiJoin method should be join conditions, not just
fields.
Check the example usage in RelMetadataTest.java#checkPredicates L1435.
- Haisheng
--
发件人：Chia-Hung Lin
日 期：2019年06月26日 05:38:30
收件人：
主 题：How to do
A quick question. I am trying to do semiJoin(). The code looks like below.
val subquery = builder.
scan("foodmart", "customer").
filter(builder.equals(builder.field("city"), builder.literal("Albany"))).
project(builder.field("customer_id")).
build
val mainquery =
