We have an application generated query using a view that has two tables joined on a LEFT OUTER join. When filtering by fields from just one table (either table) an index seek happens and it’s reasonably fast. When the where clause includes conditions for fields from both tables using an OR the query plan switches to a table scan and doesn’t utilize any of the indexes.
All four fields that are being filtered on are indexed on their respective tables.
Fast query plan where I filter on 3 fields from one table: https://www.brentozar.com/pastetheplan/?id=Hym_4PRSO
Slow query plan where I filter on four fields…three from one table and one from another table: https://www.brentozar.com/pastetheplan/?id=r1dVNDRHO
Ideally I would like to understand why this is happening and how to nudge the query engine to utilize all the indexes.