feat(storage): avoid copy key slice in storage table iter when unnecessary

[wenym1]

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What's changed and what's your intention?

Previously in the iter of StorageTable and StateTable, we yield KeyedRow, which includes the TableKey<Bytes> of the row. The TableKey<Bytes> is created by copying from a key slice yielded from StateStoreIter. Creating such TableKey<Bytes> involves memory allocation and slice clone, which may incur extra cost. However, in some cases, the key is discarded and not used, which makes the extra cost unnecessary. The key is used mostly for sorting the result of multiple iters, and when the key is not used, we don't have to create the key.

Therefore, in this PR, we will try to avoid creating unnecessary keys. In StorageTable, the key is kept for doing merge_sort. merge_sort is used only when specified ordered = true and having more than one vnodes. Therefore, when merge_sort is not used, we change to return a stream that only yields OwnedRow, and when using merge_sort, we will include the key in the input of merge_sort, and then discard the key in the output.

The iter_xxx methods of StorageTable and StateTable previously yield the KeyedRow. In this PR, the items of these methods become OwnedRow. Some streaming executors may still need the KeyedRow for sorting, and therefore we provide an extra iter_keyed_row_with_prefix as a counterpart to iter_with_prefix and yield KeyedRow. So as is methods that call iter_log.

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[wenym1]

• feat(snapshot-backfill): introduce state to snapshot backfill #19720
• feat(storage): avoid copy key slice in storage table iter when unnecessary #19717 👈 (View in Graphite)
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[stdrc]

The state table & executor parts LGTM

[hzxa21]

LGTM