Surprising SQL speed increase
I’ve just found out that the execution plan performance between the following two select statements are massively different: select * from your_large_table where LEFT(some_string_field, 4) = ' 2505 ' select * from your_large_table where some_string_field like ' 2505% ' The execution plans are 98% and 2% respectively. Bit of a difference in speed then. There are lots of places in our SQL where we use LEFT(something, x) = 'string' This should be replaced by the LIKE command for greater speed. I actually found this out by checking the LINQ generated SQL against my hand crafted SQL. I assumed the LIKE command would be slower, but is in fact much much faster.