Re: CTE subquery referencing phantom records - Mailing list pgsql-bugs

From Dave Bothwell
Subject Re: CTE subquery referencing phantom records
Date
Msg-id CAEX8mgv5ek-gDemfXrrhUqYBU8M9BV=bf7XC1UDRQE78+peiZA@mail.gmail.com
Whole thread Raw
In response to Re: CTE subquery referencing phantom records  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-bugs
Hi Tom

Thank you for your quick response. I have done some additional research and I understand now that adding the materialized key word simply returns the query to its default behavior prior to PostgreSQL 12.

Thank you for your help.
Dave

On Tue, Mar 28, 2023 at 3:31 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Dave Bothwell <dbothwell@primepoint.com> writes:
> Common Table Expression issue in PostgreSQL 15
> The final WHERE statement in our CTE appears to be referencing more
> records, then the first subquery of our CTE is returning. It works when the
> first subquery is filtered by the primary key (We left a commented out
> example in the WHERE statement). It fails when the first subquery is
> filtered by a string. We have provided a complete example of the problem
> below (The following example works in PostgreSQL 11):

I don't think this is a Postgres bug: your query is making unwarranted
assumptions about the order in which different WHERE clauses will be
evaluated.  You could return to the PG 11 behavior by marking the
CTE as "materialized":

with
phase_in_date as materialized ( ...

but it'd be better to make the data structure more normalized so that
you don't have hazards like applying date() to fields for which it
would fail on some rows.

                        regards, tom lane


--

David Bothwell

Chairman of the Board, Chief technology Officer | Primepoint, LLC

Address: 2 Springside Road, Westampton, NJ 08060

Phone: 800-600-5257

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