QLDB doing a full table scan when using an OR across two indexed fields

Question

We have a table T with two indexed fields A and B. When we query the table using the following query, QLDB does a full table scan (by evidence of the IO stats and latency):

```
select * from T where A = 'x' or B = 'y'
```

Why? And is that expected?

Answer

Well, a team member just pointed out that it is not supported according to this https://qldbguide.com/guide/data-design/#transaction-timeout

```
 --Multiple indexed fields (VIN, LicensePlateNumber) lookup using the OR operator
 --Disjunctions not currently supported 
 SELECT * FROM VehicleRegistration
 WHERE VIN = '1N4AL11D75C109151' OR LicensePlateNumber = 'LEWISR261LL'
```

This seems like a bizarre omission.

QLDB doing a full table scan when using an OR across two indexed fields

Relevanter Inhalt