SQL Server Performance Forum – Threads Archive
How much should be the sample amount in %i am wondering how much should be the sample in % for ‘update statistics used by query optimizer’ option in maint plan.What are the advantages and disadvantages of keepin a sample as 60%
60% means: 60% of the data for that table (or all database) will be access to update statistics. More %, more time. If you use option Full Scan, that means 100%. In big databases I use 10% every day and 100% on weekend. Luis Martin
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BOL specifies: use SAMPLE number with PERCENT or ROWS.
If the PERCENT, ROWS, or number option results in too few rows being sampled, SQL Server automatically corrects the sampling based on the number of existing rows in the table or view. The default behavior is to perform a sample scan on the target table or indexed view. SQL Server automatically computes the required sample size. In general I wouldn’t this option while running UPDATE STATISTICS, as the SQL takes care when it is processing the tables. Satya SKJ
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