Adaptive Spatio-Temporal Query Strategies in Blockchain
Round 1
Reviewer 1 Report
This paper presents a new indexing structure for spatio-temporal queries in blockchain applications. The topic is interesting and the proposed approach is reasonable. However, the paper suffers the following major problems:
1. The query workloads in the experiments are not realistic. In real-life, it is unlikely to have queries following Gaussian distributions. I suggest the authors to employ other types of query workloads in the experiments. Unrealistic query workloads will result in incorrect or misleading conclusions.
2. There are numerous grammatical errors throughout the paper. For example, the heading of Section 5 "Discuss" should be "Discussions". I suggest the authors hire a professional English editor to proofread the paper and correct all grammatical errors.
Minor issues:
1. In Section 3.1, there are two "Definition 1" and two "Definition 4", which is confusing. Please renumber them.
2. I suggest the authors add a subsection in Section 2 to describe Verkle trees and Merkle trees.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript proposes an adaptive spatio-temporal blockchain index method which adds the verification of time and location without additional storage and realizes the spatio-temporal index with an encrypted signature. This comes with an adaptive tree structure adjusting algorithm based on the historical query for optimized index structure. The authors claim that their method can effectively embed the spatio-temporal data into the blockchain in which the query efficiency is better than the existing static spatio-temporal index blockchain method.
General Comments:
The field of study is relatively new and the article is well written, the methodology is sound, the results are clearly presented, and the conclusions are well documented.
I have the following comments that the authors may address to improve the quality of the paper.
Better if the acronyms are explained in the first instance for readability for example SPV, TMBR.
Specific comments:
Line 36: the word “mmutability” seems a typo
Section 5 heading: Better change to the standard form “Discussion”
Line 77, 79, 86: better to keep the consistency of wordings e.g. spatiotemporal
Line 82: “belong to child node A, b, e belong to child node B” confusing. Suggest reward.
Line 84: (c) should be capital
Line 220, 223: P should be simple
Figure 4: Leaf B,πcd should this be B,πcde ?
Line 367: A reference, URL or link may be nice if possible (if it is a publicly available dataset)
Line 394: is it KD-tree?
Line 396: is it PokeMan, capital/simple letters often mixed up throughout the article which affects for the consistency and readability e.g.: Line 109, 162, 163, 462, 468, 475 verkle, Line 473 blockdag (also mentioned as Block-DAG in few places), Line 394 KD-tree
Figure 10: better if this figure is enlarged
Line 446: It is not clear why only the longitude is stored in spatial objects as it is not possible to define a location only with longitude. Better this is explained if done with a purpose.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
In ijgi-1761893, Chen & Liang presented adaptive spatio-temporal query index strategies called Verkle AR*-tree in blockchain.
S1. The authors integrates and adapted the existing Verkle tree [10].
S2. Experimental results show the superiority of Verkle AR*-tree over the existing works like Verkle R*-tree and Merkel KD-tree.
W1. Performance of Verkle R*-tree was not visible in Figure 8. Maybe it was overlapped with one of the two curves. If so, which one?
W2. Performance of transaction vector commitment was also not visible in Figure 11. Maybe it was overlapped with one of the four curves. If so, which one?
W3. As a suggestion, would it be better to rename Section 5 to "Discussion"?
W4. It would be nice if the authors could add more description to existing Verkle tree such as Verkle R*-tree.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors addressed my comments point by point. I am satisfied with most of the authors' revision, but not satisfied with the authors' response #1. I would like to suggest the authors to
1. Add more experiments with other distributions in the paper.
2. Include some of the contents of the author's response #1 in the paper.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
I am satisfied with the authors' revision. I recommend the paper to be accepted for publication in this journal.
