Re: Fixing backslash dot for COPY FROM...CSV

On Tue, 19 Dec 2023 at 02:06, Daniel Verite <daniel(at)manitou-mail(dot)org> wrote:
>
> Hi,
>
> PFA a patch that attempts to fix the bug that \. on a line
> by itself is handled incorrectly by COPY FROM ... CSV.
> This issue has been discussed several times previously,
> for instance in [1] and [2], and mentioned in the
> doc for \copy in commit 42d3125.
>
> There's one case that works today: when
> the line is part of a multi-line quoted section,
> and the data is read from a file, not from the client.
> In other situations, an error is raised or the data is cut at
> the point of \. without an error.
>
> The patch addresses that issue in the server and in psql,
> except for the case of inlined data, where \. cannot be
> both valid data and an EOF marker at the same time, so
> it keeps treating it as an EOF marker.

I noticed that these tests are passing without applying patch too:
+++ b/src/test/regress/sql/copy.sql
@@ -38,6 +38,17 @@ copy copytest2 from :'filename' csv quote '''' escape E'\\';

select * from copytest except select * from copytest2;

+--- test unquoted .\ as data inside CSV
+
+truncate copytest2;
+
+insert into copytest2(test) values('line1'), ('\.'), ('line2');
+copy (select test from copytest2 order by test collate "C") to :'filename' csv;
+-- get the data back in with copy
+truncate copytest2;
+copy copytest2(test) from :'filename' csv;
+select test from copytest2 order by test collate "C";

I was not sure if this was intentional. Can we add a test which fails
in HEAD and passes with the patch applied.

Regards,
Vignesh