When can a stream (ordered) aggregate beat a hash aggregate?

Problem Statement

Explanation

With input sorted by group keys, a streaming aggregate walks once and emits groups as they change. It avoids building a hash table and reduces memory. Hash aggregate is great for large, unsorted sets but may spill if memory is tight.

Code Solution

SolutionRead Only

SELECT customer_id, SUM(total)
FROM orders
GROUP BY customer_id;
-- index on (customer_id) enables stream aggregate

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Query Optimization & Execution Plans

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When can a stream (ordered) aggregate beat a hash aggregate?

Problem Statement

Explanation

Code Solution

Practice Sets

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Master Interviews Anywhere, Anytime

When can a stream (ordered) aggregate beat a hash aggregate?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime