【问题标题】:Get rows with missing id in Redshift在 Redshift 中获取缺少 id 的行
【发布时间】:2016-12-15 13:51:28
【问题描述】:

我有类似的东西

id | name
---|-----
1  | Sarah
3  | Pat
4  | Lea

我正在寻找缺失的行。我尝试使用 generate_series 和左连接,但这是您在 Redshift 中无法执行的操作,因为不支持 generate_series

没有临时表可以吗?

编辑

终于with a temporary table (0 to 1_000_000) 看到答案了。

【问题讨论】:

  • 您需要临时表或子查询。因为你需要一些东西来告诉你什么是全套,知道缺少什么。所以答案是NO
  • 你怎么知道哪一行是“缺失”的?
  • @a_horse_with_no_name 系列中的 ID 缺失。
  • 你为什么在乎?生成的 ID 不应该是无间隙的(尤其是如果它们是由序列生成的)。

标签: sql amazon-web-services amazon-redshift


【解决方案1】:

这可能不是最优的。但我就是这样做的

-- create temporary table
CREATE TABLE series (id INT) SORTKEY(id);

-- insert 0 to 1_000_000
INSERT INTO series 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;

-- Why not
VACUUM series;

-- LEFT OUTER JOIN with table inverted and with the interval
SELECT *
FROM series
LEFT OUTER JOIN other_table ON series.id = other_table.id
WHERE series.id BETWEEN 0 AND 4
ORDER BY series.id;

【讨论】:

    猜你喜欢
    • 1970-01-01
    • 2012-09-01
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    相关资源
    最近更新 更多