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https://issues.apache.org/jira/browse/CALCITE-1941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16137498#comment-16137498
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Julian Hyde commented on CALCITE-1941:
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[~maryannxue], Reviewing
https://github.com/apache/calcite/pull/515/commits/68cdbab99bcbd719b8159833e4fe16718ec3a101:
* Can you please add more description of the proposed changes to this JIRA case;
* Should we also change {{Schema.contentsHaveChangedSince(long, long)}}?
* In SchemaVersion please state the partial order contract more explicitly:
reflexive: if a.equals(b) then a.lessThanOrEqualTo(b); transitive: if a.
lessThanOrEqualTo(b) and b. lessThanOrEqualTo(c) then a.lessThanOrEqualTo(c);
anti-symmetric: if a.lessThanOrEqualTo(b) and !a.equals(b) then
!b.lessThanOrEqualTo(a); also, implementations must override equals, hashCode
and toString.
* I notice that distributed systems clocks e.g. [Lamport
timestamps|https://en.wikipedia.org/wiki/Lamport_timestamps] typically use a
*strict* partial order (i.e. {{!a.happensBefore(a)}}). Do you think ours be
strict also?
> Refine interface Schema#snapshot()
> ----------------------------------
>
> Key: CALCITE-1941
> URL: https://issues.apache.org/jira/browse/CALCITE-1941
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.13.0
> Reporter: Maryann Xue
> Assignee: Maryann Xue
> Priority: Minor
> Fix For: 1.14.0
>
>
> The current Schema#snapshot(long timestamp) interface is limited, for it
> assumes that users only use timestamp for schema version control, thus we
> need something new to replace the "timestamp" parameter.
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