flink sql聚合后collect收集数据问题

源表三个字段 name, color, ts 按时间窗口聚合后想根据name group by取colors数组

create table source_table ( name STRING, color STRING, ts TIMESTAMP, WATERMARK ts for ts )

create table sink_table ( name STRING, colors ARRAY )

1. 请问这个select语句要怎么写？ select name, collect(color) as colors from source_table group by tumble(ts, interval '5' seconds) 这里collect(color)返回的是multiset类型，怎样转成Array类型呢？

2. 如果array元素很多，我只想取其中N个，该怎么写flink sql?

3, 若取出现次数最多的前N个，又该怎么写flink sql? select name, collect(color) as colors from ( select name, color from ( select , ROW_NUMBER() OVER (PARTITION BY name ORDER BY color_cnt desc) AS row_num from ( select name, color, count() as color_cnt group by name, color, tumble(ts, interval '5' seconds) ) ) where row_num < 5 ); 是这样写么？*来自志愿者整理的flink邮件归档