Currently when you are using a multi tenant entity Outsystems automatically adds the tenant_id to the end of any user index that it creates. This however is not always the best ordering for an index.

For example if you have a DateTime field in an index the actual created index would be [StartDateTime],[Tenant_ID]. In this scenario SQL would first have to search though the StartDateTime order across all tenants and then the Tenant_ID. The more efficient ordering would be [Tenant_ID],[StartDateTime] which would allow SQL to pre filter out all other tenants and then just filter through what’s left in the StartDateTime index.

Of cause this won't be the best case for ALL index's, for example [isActive],[Tenant_ID] is probably a perfectly valid order as SQL could pre filter out ½ the data quickly and then filter down the tenant.

So what I would like to see is that when creating an index for a multi tenant entity is to have Tenant_ID show as one of the available index fields which will allow the developer to choose. If you wanted to ensure that Tenant_ID was always used somewhere then you could make it compulsory to have it at some point in the index field list but just allow the dev to control the order.