UnionAll變更相容性 - Realtime Compute for Apache Flink

本文為您介紹Union All變更的可相容性和不可相容性詳情。

可相容的變更

調整Union All的輸入Query的順序，對下遊有狀態運算元屬於完全相容變更。

create table MyTable2 (
  a int,
  b bigint,
  c varchar,
  d int
);

-- 原始SQL。
select a, sum(b), max(c) from (
  select a, b, c from MyTable union all select a, b, c from MyTable2
) group by a;


--調整Union All的輸入Query的順序，該修改屬於完全相容修改。
select a, sum(b), max(c) from (
  select a, b, c from MyTable2 union all select a, b, c from MyTable
) group by a;

不相容的變更

添加或刪除Union All的輸入Query，對下遊有狀態運算元屬於不相容性變更。

create table MyTable2 (
  a int,
  b bigint,
  c varchar,
  d int
);

-- 原始SQL。
select a, sum(b), max(c) from (
  select a, b, c from MyTable union all select a, b, c from MyTable2
) group by a;

create table MyTable3 (
  a int,
  b bigint,
  c varchar,
  d int
);

-- 添加Union All的輸入Query，該修改屬於不相容修改。
select a, sum(b), max(c) from (
  select a, b, c from MyTable
  union all
  select a, b, c from MyTable2
  union all
  select a, b, c from MyTable3
) group by a;