Re: BUG #17932: Cannot select big bytea values(>500MB)

From: duc hiep ha <haduchiep(at)googlemail(dot)com>
To: John Naylor <john(dot)naylor(at)enterprisedb(dot)com>
Cc: pgsql-bugs(at)lists(dot)postgresql(dot)org
Subject: Re: BUG #17932: Cannot select big bytea values(>500MB)
Date: 2023-05-18 07:23:43
Message-ID: CAM2ukhJFmnLjDd6cF9GN1zgkz82hb9xndmxmoKvv7LEvxdzxeQ@mail.gmail.com
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Hello John Naylor,

Thank you very much for your support. After setting the "bytea_output" to
"escape" and increasing the Java heap size of DBeaver (to 8GB), I can now
see the big column (bytea > 500MB). I am still in the testing phase and
haven't finished yet, but I wonder if clients with small RAM will be able
to select these big columns or if bytea_output=escape will be visible in
the application. Could you please explain this to me in more detail?

Thanks

Vào Th 3, 16 thg 5, 2023 vào lúc 08:58 John Naylor <
john(dot)naylor(at)enterprisedb(dot)com> đã viết:

> On Mon, May 15, 2023 at 5:21 PM PG Bug reporting form <
> noreply(at)postgresql(dot)org> wrote:
>
> > I created a big bytea value and try to select it from a table, I get
> > an error, something like: "ERROR: invalid memory alloc request size
> > ...".
> > it means i can insert data into table but then i can't even work
> > with it. is it a bug? could you please help me to solve this Problem.
> > Thank you very much for your support
>
> This is a known (but not documented as far as I know) issue, but it also
> depends on the data contents and how the value is retrieved. Possible
> workarounds:
>
> 1. If the data is largely printable ASCII, then try
> setting "bytea_output" to "escape":
>
>
> https://www.postgresql.org/docs/devel/runtime-config-client.html#GUC-BYTEA-OUTPUT
>
> 2. Request binary transmission in your application (if possible), for
> example "show_binary_results" in
>
> https://www.postgresql.org/docs/devel/libpq-example.html
>
> 3. COPY out using binary format
>
> --
> John Naylor
> EDB: http://www.enterprisedb.com
>

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