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https://issues.apache.org/jira/browse/CALCITE-6852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17929614#comment-17929614
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Alessandro Solimando commented on CALCITE-6852:
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[~jensen], in such cases it's useful to show exactly what you tried with a code
snippet (if small enough) or a commit/branch somewhere (even in your own fork),
with clear instructions of what you want to achieve.
Ideally, what you want to achieve could be expressed with explicit "asserts"
on what expression you'd like to build, very much like what you'd write in a
regular unit test.
In this way you avoid a lot of back and forth and whoever wants to help can
iterate faster and without ambiguity (as soon as the test "passes", they found
the right way).
> Project's digest calculation error, should include FieldNames in rowType
> -------------------------------------------------------------------------
>
> Key: CALCITE-6852
> URL: https://issues.apache.org/jira/browse/CALCITE-6852
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.39.0
> Reporter: Zhen Chen
> Assignee: Zhen Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.39.0
>
> Attachments: image-2025-02-22-17-19-46-706.png,
> image-2025-02-23-16-47-22-367.png, image-2025-02-23-16-53-03-724.png
>
>
> When I was building test cases for CALCITE-6850, I found that the results did
> not meet my expectations. When debugging the code, I discovered that the
> project's digest calculation did not include column names, This leads to the
> inability to correctly find the correct project during the findBestExp
> process.
> debug picture:
> !image-2025-02-22-17-19-46-706.png|width=553,height=245!
> I think we need to add column names in computing project's degist like this:
> {code:java}
> // code now
> protected int deepHashCode0() {
> return Objects.hash(traitSet, input.deepHashCode(), exps, hints);
> }
> // should change to
> protected int deepHashCode0() {
> return Objects.hash(traitSet, input.deepHashCode(),
> exps, hints, getRowType().getFieldNames());
> }{code}
> This change will affect some cases and the results of these cases need to be
> fixed.
>
> If calcite need this change, I can pull a pr. If this issue is not fixed,
> there will be no way to find a case for issue CALCITE-6850.
>
> supplement：
> !image-2025-02-23-16-47-22-367.png|width=518,height=274!
> !image-2025-02-23-16-53-03-724.png|width=521,height=284!
> If project fields is not nested, then it wil use field name as pw key, and
> expr as pw value,but in deepHashCode(), only use pw value to compute hash
> code. So other operators has no effect. Such as Agg, it use the aggCalls as
> pw value.
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