Query: Avoid double explicit casting

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
csharp, sql
Domain
databases

Research direction

Start by tracing how the user-defined convert node and aggregate operator produce the shown SQL, focusing on the inner and outer casts. Compare the generated query before and after the change; done means the redundant double explicit cast is condensed while the aggregate type remains preserved on the server.

Written by the indexing model from the issue text.

Description

area-query

Average_with_non_matching_types_in_projection_doesnt_produce_second_explicit_cast
Right now we generate SQL like this

SELECT AVG(CAST(CAST([o].[OrderID] AS bigint) AS float))
FROM [Orders] AS [o]
WHERE [o].[CustomerID] LIKE N'A' + N'%' AND (LEFT([o].[CustomerID], LEN(N'A')) = N'A')

Those double casting, we can condense. The inner one comes from user defined convert node. Outer one is to preserve type on server when applying aggregate operator.

Dominant language
C#
Stars
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Forks
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Avg merge
2d 5h
Merged PRs (30d)
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