Deduplication变更兼容性_实时计算 Flink版(Flink)-阿里云帮助中心

本文为您介绍Deduplication修改的可兼容性和不可兼容性详情。

可兼容的变更

当基于proctime做order by且按升序排序时（order by proctime asc），可以修改除partition by key之前的字段，该修改属于完全兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 新增输入字段：d，该修改属于完全兼容变更。
SELECT a, b, c, d FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 删除输入字段：b，该修改属于完全兼容变更。
SELECT a, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 修改输入字段：c -> substring(c, 1, 5)，该修改属于完全兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM (SELECT a, b, SUBSTRING(c,1,5) as c, proctime FROM MyTable))
WHERE rk = 1;

修改partition key的顺序，该修改属于完全兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a, b, c ORDER BY proctime ASC) as rk
   FROM MyTable)
WHERE rk = 1;

-- 修改partition key顺序，该修改属于完全兼容
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY c, a, b ORDER BY proctime ASC) as rk
   FROM MyTable)
WHERE rk = 1;

当基于rowtime进行order by或基于proctime进行order by且按降序排序（order by proctime desc）时，若schema不变，该修改属于完全兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1 AND c > 10;

-- 删除一个字段，但不影响Schema，属于完全兼容变更。
SELECT a, b FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1 AND c > 10;

不兼容的修改

新增、删除、修改partition by key或者partition by key涉及字段的计算逻辑发生变化，该修改属于不兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 新增partition by字段：d，该修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a,d ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;


-- 删除partition by字段：a，该修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 修改partition by字段：a -> a + 1，该修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (ORDER BY proctime ASC) AS rk
   FROM (SELECT a + 1 AS a, b, c, proctime FROM MyTable))
WHERE rk = 1;

修改order by相关属性（排序字段和方向），该修改属于不兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 修改order key：proctime -> ts，当前修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY ts ASC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 修改order：asc -> desc，当前修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1;

当基于rowtime做order by或基于proctime进行order by且按降序排序（order by proctime desc）时，修改了输入字段，或者schema发生变化。则修改属于不兼容变更。

-- 原始SQL。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 新增输入字段：d，当前修改属于不兼容变更。
SELECT a, b, c, d FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 删除输入字段：c，当前修改属于不兼容变更。
SELECT a, b FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM MyTable)
WHERE rk = 1;

-- 输入字段：c -> substring(c, 1, 5)，当前修改属于不兼容变更。
SELECT a, b, c FROM (
  SELECT *,
   ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) AS rk
   FROM (select a, b, substring(c, 1, 5) as c, ts from MyTable))
WHERE rk = 1;