[
https://issues.apache.org/jira/browse/CALCITE-3936?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17086044#comment-17086044
]
Steven Talbot edited comment on CALCITE-3936 at 4/17/20, 8:24 PM:
------------------------------------------------------------------
Yes, the only bummer with (1) here is that probably very frequently, this rel
structure will have a Project on top of it that effectively drops away the agg
calls used for the HAVING. In that case, if we force a subselect when we see
the Filter/Aggregate/Project without considering what's above it, we'd end up
writing SQL that was less pretty and understandable than it could have been.
Perhaps there's a creative solution to that.
was (Author: swtalbot):
Yes, the only bummer with (1) here is that probably very frequently, this rel
structure will have a Project on top of it that effectively drops away the
aggregates used for the HAVING. In that case, if we force a subselect when we
see the Filter/Aggregate/Project without considering what's above it, we'd end
up writing SQL that was less pretty and understandable than it could have been.
Perhaps there's a creative solution to that.
> RelToSqlConverter changes target of ambiguous HAVING clause with a Project on
> Filter on Aggregate
> -------------------------------------------------------------------------------------------------
>
> Key: CALCITE-3936
> URL: https://issues.apache.org/jira/browse/CALCITE-3936
> Project: Calcite
> Issue Type: Bug
> Reporter: Steven Talbot
> Priority: Major
>
> ... for dialects with SqlConformance.isHavingAlias=false
> Very, very similar to -CALCITE-3593.-
> Reproducing test case in RelToSqlConverter:
> {code:java}
> @Test public void testHavingAlias2() {
> final String query = "select \"product_id\" + 1, sum(\"gross_weight\") as
> gross_weight\n" +
> " from \"product\"\n" +
> " group by \"product_id\"\n" +
> " having sum(\"product\".\"gross_weight\") < 200";
> final String expected = "SELECT product_id + 1, GROSS_WEIGHT\n" +
> "FROM (SELECT product_id, SUM(gross_weight) AS GROSS_WEIGHT\n" +
> "FROM foodmart.product\n" +
> "GROUP BY product_id\n" +
> "HAVING SUM(product.gross_weight) < 200) AS t1"
> // (or) "HAVING gross_weight < 200) AS t1"
> // (or) ") AS t1\nWHERE t1.gross_weight < 200) AS t1"
> // INSTEAD, we get "HAVING SUM(gross_weight) < 200) AS t1"
> // which on BigQuery gives you an error about aggregating aggregates
> ;
> sql(query).withBigQuery().ok(expected);
> }
> {code}
> In that one, the pattern was Project/Filter/Aggregate, here it is
> Filter/Aggregate/Project. In 3593, the project created a new alias, which got
> added to the same SELECT clause and caused the ambiguity. Here, the aggregate
> creates an alias, but the filter will write a HAVING clause using the aliases
> from before the Aggregate, and that will cause the SQL engine to think that
> the filter is on the aggregate field, rather than on the underlying field.
> Note that this is less an absurdly unlikely occurrence than it might seem
> because when Calcite's default aliasing kicks in and everything gets the name
> "$f6", "$f4", etc, so chances of a collision are higher if you have multiply
> nested selects with default aliases.
> Potential fixes:
> # force a subselect, as was done for 3593.
> # Force the expression in the HAVING to be fully aliased by table (works at
> least in BigQuery, where I tested)
> # Write the HAVING expression in terms of the aliases from the aggregate,
> rather than what's coming from the aggregate (also works on BigQuery)
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
