May 2019
Intermediate to advanced
484 pages
11h 23m
English
Content preview from Learn T-SQL Querying
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Estimated rows
When analyzing a plan retrieved from the plan cache, which is an estimated plan or query plan, only the estimations are available. In an actual plan, or query execution plan, this information is present, and it becomes useful to compare it with the actual rows we just discussed. This is because significant differences between estimated and actual rows usually expose CE issues, and whether queries are using underlying indexes efficiently.
We will discuss remediation techniques for cardinality estimation issues from Chapter 10, Tracking Performance History with Query Store, through Chapter 12, Troubleshooting Live Queries.
The Estimated Number of Rows (EstimateRows in showplan XML) shows the estimated number of rows output by ...
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