Re: BUG #16316: The application has lost the database connection:

Hi,

On Tue, Mar 24, 2020 at 05:46:33PM +0000, PG Bug reporting form wrote:
>The following bug has been logged on the website:
>
>Bug reference: 16316
>Logged by: bo li
>Email address: boli9301(at)163(dot)com
>PostgreSQL version: 12.2
>Operating system: mac os 10.15
>Description:
>
>I used a PostgreSQL 12 to storage my data. I use python to connect my SQL
>and query my SQL to export the csv file. When I want to query the table with
>500MB, there will be an error that shows the The application has lost the
>database connection. If I truncate this table, it's ok. I wonder how to fix
>this problem. Thank you
>

It's impossible to answer this question, because it's impossible to say
what's the root cause - it might be a failure at the application level,
it might be a PostgreSQL issue, or something entirely different.

You have to check if there's an error written into the PostgreSQL server
log, for example. If there is some relevant info, post it here.

It also helps to say which python drivers you're using, what's the exact
error message you get, show some code so that we can try reproducing the
issue, etc.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services