Tilted Forum Project Discussion Community - View Single Post - [SQL Server] Do positions of columns/fields affect performance?

Stompy · 05-05-2004, 10:33 AM

Say I have a table with 10 fields. The very last field has a data type of DateTime, which I frequently perform searches with.

In addition to indexing, would it make the query faster if I repositioned that field (in the table's design) so that it was in the front? Instead of being:

Field1, Field2, Field3, Field4, Field5, Field6, Field7, Field8, Field9, DateField

It would be:

DateField, Field1, Field2, Field3, Field4, Field5, Field6, Field7, Field8, Field9

Kind of a silly question, but I always wondered if field positioning had any effect on how well a query performed. In theory it makes sense because if that date field was at the front as opposed to being behind 9 other fields, it seems the DB wouldn't have to sift through as much data to find what it needs.

On the otherhand.. I have no idea how a DB actually performs the searches, so it might not matter. Just wanted additional input on this.

Thanks!

05-05-2004, 10:33 AM	#1 (permalink)
Stompy Banned from being Banned Location: Donkey	[SQL Server] Do positions of columns/fields affect performance? Say I have a table with 10 fields. The very last field has a data type of DateTime, which I frequently perform searches with. In addition to indexing, would it make the query faster if I repositioned that field (in the table's design) so that it was in the front? Instead of being: Field1, Field2, Field3, Field4, Field5, Field6, Field7, Field8, Field9, DateField It would be: DateField, Field1, Field2, Field3, Field4, Field5, Field6, Field7, Field8, Field9 Kind of a silly question, but I always wondered if field positioning had any effect on how well a query performed. In theory it makes sense because if that date field was at the front as opposed to being behind 9 other fields, it seems the DB wouldn't have to sift through as much data to find what it needs. On the otherhand.. I have no idea how a DB actually performs the searches, so it might not matter. Just wanted additional input on this. Thanks! __________________ I love lamp.