Thread: BUG #17818: CTE is not returning the right data.

The following bug has been logged on the website:

Bug reference:      17818
Logged by:          Shiau Hoay Ong
Email address:      cute_hoay88@hotmail.com
PostgreSQL version: 12.1
Operating system:   window
Description:

Hi Postgresql Support Team, today i encounter a mystery case. The Stored
Procedure is already used for sometime, but today there are some issue in
this Stored Procedure which causing the data got deleted. The scenario is
like sample below :

    WITH cte_primary_data AS
        (
            SELECT mr.id, f.feature, mr.item, mr.data_type_id
            FROM public.primary_tables mr
            INNER JOIN public.feature_tables f
                ON f.feature_id = mr.feature_id
            WHERE mr.id = 3163
                AND mr.team_id = 23
                AND mr.stage_id = 2
        )
        SELECT * FROM cte_primary_data l
        INNER JOIN temp_flat_data f
            ON l.feature = f.feature
            AND l.item = f.item

Scenario: When i execute this above query, i am not able to find the feature
AA and Item AA EXT  Inner-Lane- 1.1G. 

But weird is i tried out with this (below example: Add WHERE inside the
cte), then i am able to get the item:

WITH cte_primary_data AS
        (
            SELECT mr.id, f.feature, mr.item, mr.data_type_id
            FROM public.primary_tables mr
            INNER JOIN public.feature_tables f
                ON f.feature_id = mr.feature_id
            WHERE mr.id = 3163
                AND mr.team_id = 23
                AND mr.stage_id = 2
                AND mr.item = 'AA EXT  Inner-Lane- 1.1G'
                AND f.feature = 'AA'
        )
        SELECT * FROM cte_primary_data l
        INNER JOIN temp_flat_data f
            ON l.feature = f.feature
            AND l.item = f.item

I do try out with Create Temp Table also work fine with the sample without
need filtering (as filtering will only reduce data record set). 
Can you please help to investigate and explain what is the possible root
cause for this? 
Thanks!

The following bug has been logged on the website:

Bug reference:      17818
Logged by:          Shiau Hoay Ong
Email address:      cute_hoay88@hotmail.com
PostgreSQL version: 12.1
Operating system:   window
Description:       

Hi Postgresql Support Team, today i encounter a mystery case. The Stored
Procedure is already used for sometime, but today there are some issue in
this Stored Procedure which causing the data got deleted. The scenario is
like sample below :


I do try out with Create Temp Table also work fine with the sample without
need filtering (as filtering will only reduce data record set).
Can you please help to investigate and explain what is the possible root
cause for this?
Thanks!

PG Bug reporting form <noreply@postgresql.org> writes:
> PostgreSQL version: 12.1

> Scenario: When i execute this above query, i am not able to find the feature
> AA and Item AA EXT  Inner-Lane- 1.1G. 
> But weird is i tried out with this (below example: Add WHERE inside the
> cte), then i am able to get the item:

I agree that's strange, but ...

> Can you please help to investigate and explain what is the possible root
> cause for this? 

Nobody is going to be able to help you from that amount of information.
I would suggest, if you really are running 12.1, that your first step
should be to update to 12.latest (currently 12.14), as you are missing
more than three years worth of bug fixes.  Another useful step could be
to re-index these tables, just in case the problem is index corruption.
(Do that *after* updating.)

If you still see strange behavior, and can provide a self-contained test
case, we'd be happy to look at it.

            regards, tom lane