A filter similar in sql to `where (a,b,c) > (1,2,3)`

Using Layers
1

Looking at the record layer, it’s unclear to me how I’d go about constructing that, I was kinda thinking I could use a Query.keyExpression, but that looks like it’s reserved only for functions (practically), I kinda assumed I could do Query.concatentateFields("a", "b", "c").greaterThan(Tuple.from(1,2,3))

I tried looking through the tests, but didn’t find anything. I guess I could create a function Quey.keyExpression(function("tupleize", fields("a", "b", "c"), but I assume that would mean a table scan? a, b, c are my primary key

2

Yeah, unfortunately, there’s not a single function for that. In theory, it’s logically equivalent to something like:

Query.or(
    Query.and(Query.field("a").equalsValue(1), Query.field("b").equalsValue(2), Query.field("c").greaterThan(3)),
    Query.and(Query.field("a").equalsValue(1), Query.field("b").greaterThan(2)),
    Query.field("a").greaterThan(1)
)

But, (1) that’s a bit unwieldy and (2) the planner isn’t quite smart to notice that if you have an index on concatenateFields("a", "b", "c"), the given ranges can be used to turn that into a single scan.

If you did introduce a tupleize function and made it a QueryableKeyExpression, then you certainly could index the result of that function. Assuming the index exists, the planner should chose it for you with something like the expression you suggested.

It’s a bit unsatsifying, but I think the most straightforward way to get this to work is actually to forego the planner and just issue an index scan directly. Something like:

recordStore.scanIndexRecords(
    indexName,
    IndexScanType.BY_VALUE,
    new TupleRange(Tuple.from(1, 2, 3), null, EndpointType.RANGE_EXCLUSIVE, EndpointType.TREE_END),
    continuation // null if starting from the beginning; previous run's continuation if resuming a scan
    scanProperties // specifies forward/reverse as well as limits
);

If you know you have the index you want, this can be simpler than trying to get the planner to produce the thing you want.

1 Like
3

Yep I came to the exact same conclusion! I should have responded to myself.

This is quite an impressive piece of technology and thank you for the help!

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