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https://issues.apache.org/jira/browse/CALCITE-6090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17783885#comment-17783885
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Ulrich Kramer edited comment on CALCITE-6090 at 11/8/23 6:08 AM:
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My initial assumption is not correct. Removing [this block
title|https://github.com/apache/calcite/blob/590ec85f0fcff7173c288c350c3f60e640976a34/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L2094-L2105]
will not fix the problem. Without this block, the generated logical plan
contains a identity projection, which is optimized away.
was (Author: kramerul):
My initial assumption is not correct. Removing [this block
title|https://github.com/apache/calcite/blob/590ec85f0fcff7173c288c350c3f60e640976a34/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L2094-L2105]
will not fix the problem. Without this block, the generated logical plan
contains a identity projection, which is optimized away. The problem is that
the generated {{LogicalAggregate}} already has a row type with a column name
{{latest_store_type}}. This is not correct. It should have an anonymous column
name.
> Jdbc adapter may create wrong sql for joins
> -------------------------------------------
>
> Key: CALCITE-6090
> URL: https://issues.apache.org/jira/browse/CALCITE-6090
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.35.0
> Reporter: Ulrich Kramer
> Priority: Major
>
> Adding the following unit test to {{JdbcAdapterTest}} leads to an error
> {code:java}
> @Test void testAmbiguousColumn() {
> CalciteAssert.model(JdbcTest.FOODMART_SCOTT_MODEL)
> .query("select\n" +
> " \"store_id\" \"latest_id\",\n" +
> " max(\"store_type\") \"latest_store_type\"\n" +
> " from\n" +
> " ( SELECT \"store_id\",\"store_type\" FROM
> \"foodmart\".\"store\") \n" +
> " group by\n" +
> " \"store_id\"")
> .runs()
> .enable(CalciteAssert.DB == CalciteAssert.DatabaseInstance.HSQLDB)
> .explainContains("JdbcToEnumerableConverter\n JdbcProject" )
> .planHasSql("SELECT MAX(\"region_id\") AS \"latest_region_id\",
> \"store_id\" AS \"latest_id\"\nFROM \"foodmart\".\"store\"\nGROUP BY
> \"store_id\"");
> }
> {code}
> The projection for the column {{latest_id}} is missing. The problem is
> located
> [here|https://github.com/apache/calcite/blob/590ec85f0fcff7173c288c350c3f60e640976a34/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L2094-L2095].
> If the aggregation doesn't add, remove or twist columns,
> {{RexUtil.isIdentity}} returns true. Additionally the {{inputRowType}}
> already contains the names of the output columns. Therefore
> {{fieldNameList.equals(inputRowType.getFieldNames())}} also returns true.
> Normally, this doesn't cause issues. But if this statement is used within a
> join like this
> {code:sql}
> SELECT
> DISTINCT "region_id",
> "store_id",
> "dummy"
> FROM
> (
> SELECT
> "region_id",
> "store_id",
> "dummy"
> FROM
> (
> select
> B."store_city" "store_city",
> B."store_id" "store_id",
> B."region_id" "region_id",
> cast(null as integer) "dummy"
> from
> (
> select
> A."store_city" "store_city",
> A."region_id" "region_id",
> A."store_id" "store_id"
> from
> (
> select
> max("region_id") "latest_region_id",
> "store_id" "latest_id"
> from
> ( SELECT "region_id", "store_id" FROM "foodmart"."store")
> "C"
> group by
> "store_id"
> ) "D"
> left outer join "foodmart"."store" A on (
> A."store_id" = "D"."latest_id"
> and A."region_id" = "D"."latest_region_id"
> )
> ) B
> )
> WHERE
> "store_city" IS NOT NULL
> )
> {code}
> an invalid SQL will be generated because the left and the right side of the
> join has a column "store_id". This will be fixed in
> {{SqlValidatorUtil::addFields}} by appending a unique number. But in the end
> this will result in a statement, which contains a {{GROUP BY ... store_id0}}
> and will never be successful.
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