Unused CTE affects result set

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От Gabriel Sánchez
Тема Unused CTE affects result set
Дата
Msg-id CANHuRqHUR+a0TEF7WXLNN1+_=6CjET-jtu=QFuEPJ875oMHC7A@mail.gmail.com
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Ответы Re: Unused CTE affects result set
Список pgsql-general
Dear Postgres community,

I'm seeing unintuitive behavior with a query structured as follows:

WITH used_cte (SELECT a, b, c FROM t1 ...)
, unused_cte (SELECT d, e, f FROM t2 ...)
SELECT * FROM used_cte ...
-- returns no results

WITH used_cte (SELECT a, b, c FROM t1 ...)
-- , unused_cte (SELECT d, e, f FROM t2 ...)
SELECT * FROM used_cte ...
-- returns results

I don't understand why the presence of a CTE that ends up not being included in the final query affects the result set.  Could this be a bug, or is there something I don't understand?

PostgreSQL 14.9 (Ubuntu 14.9-0ubuntu0.22.04.1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0, 64-bit

Thanks,
Gabriel


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