[
https://issues.apache.org/jira/browse/CALCITE-1098?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jane Lian closed CALCITE-1098.
------------------------------
Resolution: Not A Problem
> Set Mergence trigger relNode cyclical reference (ProjectMergeRule)
> ------------------------------------------------------------------
>
> Key: CALCITE-1098
> URL: https://issues.apache.org/jira/browse/CALCITE-1098
> Project: Calcite
> Issue Type: Bug
> Reporter: Jane Lian
> Assignee: Julian Hyde
> Attachments: projectMergeTest.patch
>
>
> The issue is found in applying ProjectMergeRule. Following is the case which
> triggers the relNode's cyclical reference.
> For instance suppose you have following set tree:
> {code}
> Set#2: Project
> rel#3:Subset#2.NONE
> rel#4: (‘a’) with input (rel#5:Subset#1.NONE)
> Set#1: Project
> rel#5:Subset#1.NONE
> rel#6: (‘a’) with input (rel#7:Subset#0.NONE)
> Set#0: TableScan
> rel#7:Subset#0.NONE
> rel#8:Dept
> {code}
> Project#2- Project#1 triggers the ProjectMerge Rule, then a new equivalent
> Project will be generated, such as,
> rel#9: (‘a’) with input (rel#7:Subset#0.NONE).
> When the planner is registering rel#9, it will try to find the equivalent
> relNode which is reserved in mapDigestToRel. In the above case, rel#6 would
> be found. The set#2 and set#1 would be merged, then the following is the set
> tree after mergence:
> {code}
> Set#1: Project
> rel#5:Subset#1.NONE
> rel#4: (‘a’) with input (rel#5:Subset#1.NONE)
> rel#6: (‘a’) with input (rel#7:Subset#0.NONE)
> Set#0: TableScan
> rel#7:Subset#0.NONE
> rel#8: Dept
> {code}
> rel#4's input is set#1, then there is a cyclical reference.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
