Re: Trouble Upgrading Postgres

Daniel said:

>It's plausible that, with only 4GB of RAM, the table that fails
to dump has some very large rows that can't be allocated, especially
since both the backend and pg_dump need to have it simultaneously
in memory.
> >pg_dump: The command was: COPY public.docfile (docfile_pkey, 
> >docfileoriginalname, ordernumber, versionnum, docfilecontents, 
>> docfilepath, docfileextension, enddatetime, endby, editnum, insby, 
>> insdatetime, modby, moddatetime, active, doc_fkey) TO stdout;
>The "docfilecontents" column suggests that it might contain
large contents. If its type is bytea, it's going to be expanded
to twice its size to build the hex representation.
>You may get a sense on how big is the biggest row expressed
as text with this query:
 SELECT max(length(contents.*::text)) FROM public.docfile;
>If it's big enough that it might cause the OOM issue,
try to run pg_dump remotely through an SSH tunnel [1], which you
can already do in terms of network permissions since you log in with
SSH, so pg_dump itself does not use any memory on the server.
>Also, if the machine doesn't have swap space, it might be
that just adding a few GB's of swap would make the operation
succeed.

This appears to be the case. I ran:

SELECT max(length(docfilecontents::text)) FROM docfile;

 and after a very long time, got: