Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/19258 )

Change subject: KUDU-3371 [util] add NextOf method for ObjectIdGenerator
......................................................................


Patch Set 2:

(5 comments)

http://gerrit.cloudera.org:8080/#/c/19258/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/19258/2//COMMIT_MSG@9
PS2, Line 9: use
nit: using


http://gerrit.cloudera.org:8080/#/c/19258/2//COMMIT_MSG@10
PS2, Line 10: usage cases
nit: use cases


http://gerrit.cloudera.org:8080/#/c/19258/2//COMMIT_MSG@12
PS2, Line 12: plus 1, to act as the upper exclusion key when scan.
... plus 1: that's to provide an exclusive upper bound when scanning


http://gerrit.cloudera.org:8080/#/c/19258/2/src/kudu/util/oid_generator.h
File src/kudu/util/oid_generator.h:

http://gerrit.cloudera.org:8080/#/c/19258/2/src/kudu/util/oid_generator.h@47
PS2, Line 47: static size_t IdLength() { return 32; }
Add 'constexpr' to the signature to allow for compile-time optimization?

Also, where is it used?  I couldn't find it anywhere in the newly added tests 
or in the implementation of the new NextOf() method.


http://gerrit.cloudera.org:8080/#/c/19258/2/src/kudu/util/oid_generator.cc
File src/kudu/util/oid_generator.cc:

http://gerrit.cloudera.org:8080/#/c/19258/2/src/kudu/util/oid_generator.cc@68
PS2, Line 68:   string next(id);
            :   next[next.size() - 1] += 1;
            :   return next;
Just curious why to choose this approach instead of appending an extra 
character.  Is it more efficient in predicates to use for RocksDB queries?

If using using (id + ".") or (id + "0") instead, that way it's more obvious the 
value isn't a UUID (and it's not supposed to be, right)?  In addition, (id + 
".") comes before NextOf(id) in any locale and can be used as inclusive bound 
as well if all the values are UUIDs of a fixed pre-determined length.

$ printf "abc\nabd\nabc.\nabc0\n" | sort
abc
abc.
abc0
abd



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I293baa379e8d64adc4ff93acdb0713aae2731c7d
Gerrit-Change-Number: 19258
Gerrit-PatchSet: 2
Gerrit-Owner: Yingchun Lai <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: KeDeng <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Yifan Zhang <[email protected]>
Gerrit-Reviewer: Yingchun Lai <[email protected]>
Gerrit-Reviewer: Yuqi Du <[email protected]>
Gerrit-Comment-Date: Tue, 29 Nov 2022 08:51:50 +0000
Gerrit-HasComments: Yes

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