Is 80/20 a 90’s Estimate?
It has often been said that even the most write intensive OLTP databases have an average of 80% reads and 20% writes. I am thinking interactivity has increased in applications because technology has allowed it to get more write intensive but I am just guessing.
Run this on your OLTP Crown Jewels and post the results. While not very scientific, it will give us some anecdotal data. The query could also be useful when sizing new hardware.
I came up with 97/3, 74/26 and 60/40 on three high volume databases.
--This query has minimal impact.
Post your results! This content is published under the Attribution-Share Alike 3.0 Unported license.
--Looks at index metadata to determine readwrite ratio since the last restart of the instance.
SELECT
CAST(SUM(user_seeks+user_scans+user_lookups) AS decimal)/CAST(SUM(user_updates)+SUM(user_seeks+user_scans+user_lookups) AS decimal)
AS ReadPercent
, CAST(SUM(user_updates) AS decimal)/CAST(SUM(user_updates) + SUM(user_seeks + user_scans + user_lookups) AS decimal)
AS WriteRatio
FROM sys.dm_db_index_usage_statsComments
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