I am wondering if someone can help me understand the following query execution behavior:
I have two similar tables and table2 consists of 5000000 records.
Query: INSERT INTO table1 SELECT * FROM table2.
Execution Time: A ms.
Query: INSERT INTO table1 SELECT * FROM table2.
Execution Time: B ms.
Sometimes B >> A (B is very larger than A). Both queries are same and run twice. What could be the reason that the same query is taking very long sometime?