Showing posts with the label greenplum

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SQL Query: 3 Methods for Calculating Cumulative SUM

SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON >= GROUP BY, t1.value ORDER BY; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

Greenplum Database basics in the age of Hadoop (1 of 2)

The Greenplum Database constructs on the basis of open origin database PostgreSQL. It firstly purposes like a information storage and uses a shared-nothing architecture|shared-nothing, astronomically collateral (computing)|massively collateral handling (MPP) design. How Greenplum works... In this design, information is partitioned athwart numerous section servers, and every one section controls and commands a clearly different part of the altogether data; there is no disk-level parting nor information argument amid sections. Greenplum Database’s collateral request optimizer changes every one request into a material implementation design. Greenplum’s optimizer utilizes a cost-based set of rules to appraise prospective implementation designs, bears a worldwide view of implementation athwart the computer array, and circumstances in the charges of moving information amid knots. The ensuing request designs hold customary relational database transactions like well like collateral