Re: PSQL error: total cell count of XXX exceeded - Mailing list pgsql-hackers

From Hongxu Ma
Subject Re: PSQL error: total cell count of XXX exceeded
Date
Msg-id TYBP286MB03514675D5D9AA3F533DC987B4E2A@TYBP286MB0351.JPNP286.PROD.OUTLOOK.COM
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In response to Re: PSQL error: total cell count of XXX exceeded  ("David G. Johnston" <david.g.johnston@gmail.com>)
Responses Re: PSQL error: total cell count of XXX exceeded
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Thank you David.

From the code logic, I don't think this check is meant to check the limit:
If it enters the double-loop (cont.nrows * cont.ncolumns) in printQuery(), the check should be always false (except overflow happened). So, if want to check the limit, we could have done this check before the double-loop: just checking PGresult and reports error earlier.

I wouldn’t be adverse to an improved error message, and possibly documenting said limit.

Agreed with you, current error message may even report a negative value, it's very confusing for user. It's better to introduce a limit here. Or using a bigger integer type (e.g. long) for them, but it's also have the theoretical upbound.

Thanks.


From: David G. Johnston <david.g.johnston@gmail.com>
Sent: Saturday, August 26, 2023 12:09
To: Hongxu Ma <interma@outlook.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: PSQL error: total cell count of XXX exceeded
 
On Friday, August 25, 2023, Hongxu Ma <interma@outlook.com> wrote:

When I tried to select a big amount of rows, psql complains a error "Cannot add cell to table content: total cell count of 905032704 exceeded."

 We should use long for ncolumns and nrows and give a more obvious error message here.

Any thoughts? or some other hidden reasons?

9 millions cells seems more than realistic a limit for a psql query result output.  In any case it isn’t a bug, the code demonstrates that fact by producing an explicit error.

I wouldn’t be adverse to an improved error message, and possibly documenting said limit.

David J.

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