proposed additional QueryKeys API method to support getting events of different types in log index order

[ettec]

Required to correctly replicate state from on chain contract that publishes multiple event types to offchain state.

For comment, tentatively agreed with @ilija42 pending inspiration from above.

[jmank88]

What about a map of Key -> Sequence?

Suggested change

	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) ([]SequenceWithKey, error)
	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) (map[string]Sequence, error)

If you are worried about ordering, could consider a sequence:

Suggested change

	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) ([]SequenceWithKey, error)
	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) (iter.Seq2[string, Sequence], error)

[ettec]

The problem with map[string]Sequence is it would lose the order, the key thing is that the order across the various event types needs to be maintained.

no strong feelings on using iter, however the result isn't streamed so no strong advantage to using iter either as far as I can see, and I think it would add a bit of complexity to the loop implementation. On balance my pref would be for []SequenceWithKey

[jmank88]

Streaming is not the only reason to use an iter.Seq, and this API is a layer above the GRPC protos. The advantage is that we can express what we need naturally and directly without declaring extra hyper-specific types. Another similar approach could be a generic entry/pair/etc.:

type Entry[K comparable, V any] struct {
	K K
	V V
}

Suggested change

	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) ([]SequenceWithKey, error)
	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) ([]Entry[string, Sequence], error)

Could also consider documenting via a type:

// SortedEntries is a slice of [Entry]s sorted by ascending keys.
type SortedEntries[K comparable, V any] []Entry[K, V]

Suggested change

	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) ([]SequenceWithKey, error)
	QueryKeys(ctx context.Context, contract BoundContract, filters []query.KeyFilter, limitAndSort query.LimitAndSort, sequenceDataType any) (SortedEntries[string, Sequence], error)