Ali Shaik's Database Diary

Introduction: SQL Server execution plans hold the key to optimizing query performance. By understanding the various operators and costs within an execution plan, you can uncover hidden inefficiencies and enhance the speed and efficiency of your queries. In this blog, we will dive deep into common operators like Index Scan, Index Seek, Nested Loops, Merge Join, and Sort, and demystify their associated costs. Index Scan: Scans the entire index to locate the requested data. The cost is directly proportional to the number of rows in the index. A high cost may indicate inadequate index utilization or non-selective queries. Index Seek: Directly seeks into the index for specific rows. The cost is proportional to the number of retrieved rows. A high cost might indicate non-selective queries or underutilized indexes. Nested Loops: Joins tables by iterating through each row in one table for matches in the other. The cost is determined by the product of rows in both tables. A high cost could sugg