CODEWITHSUNDEEP
sqlsql-servert-sql
Steve Wilson
Steve Wilson

Reputation: 23

Is it possible to get the number of rows from a table in O(1) time?

In SQL server, obviously one way of getting the number of rows in a table is

SELECT COUNT(*) FROM MyTable

but I assume that's O(n) time where n is the number of rows. Is there any metadata I can access that has the number of rows stored?

Upvotes: 1

Views: 40

Answers (1)

Lamak
Lamak

Reputation: 70638

Yes, you can use sys.partitions, it might not be the exact number, but it's extremely fast:

SELECT SUM(rows) 
FROM sys.partitions
WHERE [object_id] = OBJECT_ID('dbo.MyTable')
AND index_id IN (0,1);

Upvotes: 3

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