Re: psql - add SHOW_ALL_RESULTS option

On 4/12/21, 9:25 AM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> writes:
>>> Between this and the known breakage of control-C, it seems clear
>>> to me that this patch was nowhere near ready for prime time.
>>> I think shoving it in on the last day before feature freeze was
>>> ill-advised, and it ought to be reverted. We can try again later.
>
>> The patch has been asleep for quite a while, and was resurrected, possibly
>> too late in the process. ISTM that fixing it for 14 is manageable,
>> but this is not my call.
>
> I just observed an additional issue that I assume was introduced by this
> patch, which is that psql's response to a server crash has gotten
> repetitive:
>
> regression=# CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));
> server closed the connection unexpectedly
> This probably means the server terminated abnormally
> before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
> The connection to the server was lost. Attempting reset: Failed.
> !?>
>
> I've never seen that before, and it's not because I don't see
> server crashes regularly.

I think I've found another issue with this patch. If AcceptResult()
returns false in SendQueryAndProcessResults(), it seems to result in
an infinite loop of "unexpected PQresultStatus" messages. This can be
reproduced by trying to run "START_REPLICATION" via psql.

The following patch seems to resolve the issue, although I'll admit I
haven't dug into this too deeply. In any case, +1 for reverting the
patch for now.

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 028a357991..abafd41763 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -1176,7 +1176,7 @@ SendQueryAndProcessResults(const char *query, double *pelapsed_msec, bool is_wat

/* and switch to next result */
result = PQgetResult(pset.db);
- continue;
+ break;
}

/* must handle COPY before changing the current result */

Nathan