AWS redshift中的序列号生成功能

Question

redshift中有序列号生成功能吗？还是一个将值组合并给出数字哈希键的函数？

Answer 1

目前尚无序列的概念（如在Oracle中所见）。

您有几种选择：

• 编号表
• RANK（）或ROW_NUMBER（）窗口在整个集合中起作用。请注意，如果您有多节点群集，这可能会对性能产生负面影响。
• 定义为IDENTITY（种子，步骤）的列。注意，IDENTITY序列可能是“稀疏的”（例如，序列中有间隔）。

Answer 2

这是生成一百万个数字的另一种方法

with seq_0_9 as (
select 0 as num
union all select 1 as num
union all select 2 as num
union all select 3 as num
union all select 4 as num
union all select 5 as num
union all select 6 as num
union all select 7 as num
union all select 8 as num
union all select 9 as num
), seq_0_999 as (
select a.num + b.num * 10 + c.num * 100 as num
from seq_0_9 a, seq_0_9 b, seq_0_9 c
)
select a.num + b.num * 1000 as num
from seq_0_999 a, seq_0_999 b
order by num