如何在Oracle中将表行拆分为固定大小的块 [英] How to Split a table rows into fixed size chunk in Oracle

问题描述

我有一个超过100万行的大型表，其中一个数字列作为主键.我正在尝试使用Oracle sql查询来拆分大小，例如500.因此，我有一些存储桶，每个存储桶都有500条记录，并在该存储桶中给出了它们的最大值和最小值. 样本数据

I have a large table 1 million+ rows with a numeric column as primary key. I was trying for an Oracle sql query to get a split of size say 500. So that I have sort of buckets that have 500 records each and give their max and min value in that bucket. sample data

pk_column column1 column2 column3
1002      abcd    1234    15-apr-20
1004      efgh    3435    14-apr-20
1007      ijkl    8855    16-apr-20
....
....
....
2002      asdf    8565    17-apr-20
2005      efgh    5894    14-apr-20   

所需的输出如下所示

bucket_no no_of_element min_value max_value
1         500           1002      2002
2         500           2005      3002
3         500           3003      4002
4         480           4003      4500

我可以使用NTILE或WIDTH_BUCKET提出的代码无法确定存储区大小的数量，因此元素的种类是固定的.随着元素数量的不断变化，我无法找到一种动态计算存储桶数的方法，无法在NTILE或WIDTH_BUCKET窗口函数中使用它.以分层的方式使用LEAD和LAG功能非常令人困惑.谁能建议如何解决这个问题.

The code that I could come up with using NTILE or WIDTH_BUCKET is not able to decide the number of bucket size so that no of element is kind of fixed. As the number of elements keep changing , I am unable to find a way to calculate the bucket count dynamically and use it in the NTILE or WIDTH_BUCKET window function. Use of LEAD and LAG function in a hierarchical way was a lot confusing. Could anyone suggest how to tackle this.

推荐答案

您可以按如下方式使用解析函数ROW_NUMBER:

You can use the analytical function ROW_NUMBER as follows:

SELECT
    RN   AS BUCKET_NO,
    COUNT(1) AS NO_OF_ELEMENT,
    MIN(PK_COLUMN) AS MIN_VALUE,
    MAX(PK_COLUMN) AS MAX_VALUE
FROM
    ( SELECT T.*,
            MOD(ROW_NUMBER() OVER(ORDER BY PK_COLUMN) - 1, 500) + 1 RN
        FROM YOUR_TABL T
    )
GROUP BY RN

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