CODEWITHSUNDEEP
google-bigquery
Pavan Kumar Kattamuri
Pavan Kumar Kattamuri

Reputation: 335

Which sorting algorithm does bigquery ORDER BY clause uses?

Does it use bubble sort/merge sort.. type of algorithms? Is there any documentation/information available around the background execution of these type of statements?

Upvotes: 4

Views: 569

Answers (1)

Elliott Brossard
Elliott Brossard

Reputation: 33755

Not sure why you're being downvoted, since I don't think this is described anywhere. Within a single partition, BigQuery uses introsort, with a some tricks depending on the types and number of columns in the ORDER BY clause. For example, if you have an INT64 column named x and you run a query of this form:

SELECT x
FROM dataset.table
ORDER BY x

BigQuery will load all of the x values into a vector, then sort and return them. It's less straightforward if you have multiple columns in the select list or ORDER BY clause, though.

Upvotes: 3

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