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Allow zero key length in key and prefix for DynamoDb. #4893

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Allow zero key length in key and prefix for DynamoDb. #4893

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@MathieuDutSik
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@MathieuDutSik MathieuDutSik commented Nov 3, 2025

Motivation

Recently, the operation find_keys_by_prefix(&[]) has emerged as an operation on stores. This operation
does not work on DynamoDb since the prefix has to be non-empty as well as the key.

Proposal

Add a [1] as prefix.

Test Plan

The CI should catch the bugs. The run_reads has been updated for that.

Release Plan

  • Nothing to do / These changes follow the usual release cycle.
    It is not that important since DynamoDB is not used on TestNet Conway.

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None.

@MathieuDutSik MathieuDutSik marked this pull request as ready for review November 3, 2025 15:41
@MathieuDutSik MathieuDutSik requested review from ma2bd and ndr-ds November 3, 2025 15:41
ma2bd
ma2bd reviewed Nov 3, 2025
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So in general, value-keys can be empty but not partition-keys?

@MathieuDutSik
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MathieuDutSik commented Nov 4, 2025

So in general, value-keys can be empty but not partition-keys?

The way to deal with empty vs non-empty keys is by prefixing by [1] the key or root_key.

It used to be that we had a root_key that was empty: the infamous &[]. We no longer. So, requiring root_keys to be non-empty is a sensible decision.

There are now contexts where we need to list all the keys of a store and the command is find_keys_by_prefix(&[]). Therefore, it is sensible to allow empty keys and empty prefixes.

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afck commented Nov 4, 2025

Would an alternative be to simply use a different query (without the AND k >= ? part) if the specified prefix is empty?

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MathieuDutSik commented Nov 4, 2025

Would an alternative be to simply use a different query (without the AND k >= ? part) if the specified prefix is empty?

I tried that some years ago and as I remember it was not working. But I can retry.

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@MathieuDutSik @afck @ma2bd