Thanks a lot, Julian.
I’ll look into that the next few days.

/Moritz

On 25.01.23, 17:04, "Julian Hyde" <jhyde.apa...@gmail.com> wrote:

It would seem a reasonable and useful enhancement if CheapestPlanReplacer did 
some memoization. If it sees the same RelNode twice it should emit the same 
result. I would be conservative, and memoize based on identity of the RelNodes, 
not just equality.

It would be useful if you could come up with a test case in pure Calcite, then 
log a jira case.

Julian

> On Jan 25, 2023, at 12:56 AM, Moritz Mack <mm...@talend.com> wrote:
>
> Dear Calcite Devs,
>
> I’m currently looking into an issue in the SQL extension [1] of Apache Beam 
> and was hoping to find some advice here.
> Using a bunch of Calcite ConverterRules [2], we convert a RelNode tree into a 
> tree of BeamRelNodes which is then used to build a Beam DAG. Pretty standard 
> I suppose …
>
> What I’m scratching my head about is that applying the converter rules 
> changes the semantics of the graph, which it shouldn’t I thought. Or is that 
> a wrong expectation?
> Here’s a very simple SQL example to illustrate this (see also 
> BeamUnionRelTest [3]):
>
> SELECT  order_id, site_id, price FROM ORDER_DETAILS
> UNION ALL
> SELECT  order_id, site_id, price FROM ORDER_DETAILS
>
> This is where we start at, the corresponding RelNode:
>
> LogicalUnion.NONE(input#0=LogicalProject#8,input#1=LogicalProject#10,all=true)
>
> Once the corresponding conversion rule [4] is applied to above by the 
> CheapestPlanReplacer, but before visiting its old inputs, we get the 
> following:
>
> BeamUnionRel.BEAM_LOGICAL(input#0=RelSubset#25,input#1=RelSubset#25,all=true)
>
> At this point both inputs refer to the same node (#25). However, once 
> visiting the inputs [5] in CheapestPlanReplacer, that semantic information is 
> lost as RelNodes get copied if inputs change [5].
> In below result, the two inputs refer to different nodes:
>
> BeamUnionRel.BEAM_LOGICAL(input#0=BeamCalcRel#49,input#1=BeamCalcRel#50,all=true)
>
> This, however, currently prevents caching of intermediate results in the Beam 
> DAG when this might be beneficial.
>
> Would you have any advice how to better approach this?
> Of course, I could use a stateful copy operation to handle such repeated copy 
> operations with the same parameters. But this seems wrong to be honest.
>
> Thanks a million!
> Kind regards,
> Moritz
>
>
> [1] 
> https://urldefense.com/v3/__https://github.com/apache/beam/issues/24314__;!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrH1HemJw$<https://urldefense.com/v3/__https:/github.com/apache/beam/issues/24314__;!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrH1HemJw$>
> [2] 
> https://urldefense.com/v3/__https://github.com/apache/beam/blob/6ba647333c4c69fb6dfc65929456c7c11570382f/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/planner/BeamRuleSets.java*L136-L152__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9Ubryge2rYo$<https://urldefense.com/v3/__https:/github.com/apache/beam/blob/6ba647333c4c69fb6dfc65929456c7c11570382f/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/planner/BeamRuleSets.java*L136-L152__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9Ubryge2rYo$>
> [3] 
> https://urldefense.com/v3/__https://github.com/apache/beam/blob/6ba647333c4c69fb6dfc65929456c7c11570382f/sdks/java/extensions/sql/src/test/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamUnionRelTest.java*L52-L71__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrYLpRpco$<https://urldefense.com/v3/__https:/github.com/apache/beam/blob/6ba647333c4c69fb6dfc65929456c7c11570382f/sdks/java/extensions/sql/src/test/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamUnionRelTest.java*L52-L71__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrYLpRpco$>
> [4] 
> https://urldefense.com/v3/__https://github.com/apache/beam/blob/a96afe2c57c45a869a622086eaa4f81305f06e72/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rule/BeamUnionRule.java__;!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrQdhrgjw$<https://urldefense.com/v3/__https:/github.com/apache/beam/blob/a96afe2c57c45a869a622086eaa4f81305f06e72/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rule/BeamUnionRule.java__;!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrQdhrgjw$>
> [5] 
> https://urldefense.com/v3/__https://github.com/apache/calcite/blob/a326bd2d0e0b4b6b3336f10217b0ecbb79522239/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java*L727-L739__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrsOkL07k$<https://urldefense.com/v3/__https:/github.com/apache/calcite/blob/a326bd2d0e0b4b6b3336f10217b0ecbb79522239/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java*L727-L739__;Iw!!CiXD_PY!UU9RIn-JXhMMhXinYi6Iq3oHsLnmlLXkqWMc4A6J85FY83_atUeh4tseWCHR_L5B7bcBk_fj9UbrsOkL07k$>
>
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