[pgpool-general: 9410] Re: FATAL: failed to read kind from backend

[Ron Johnson]

On Thu, Mar 27, 2025 at 1:39 AM Ron Johnson <ronljohnsonjr at gmail.com> wrote:

> On Thu, Mar 27, 2025 at 1:04 AM Tatsuo Ishii <ishii at postgresql.org> wrote:
>
>> > PG 16.8
>> > PgPool 4.5.4
>> >
>> > Three node cluster:
>> > FISPCDSPGS302a   < Primary DB node
>> > FISPCDSPGS302b   < DB replica
>> > FISPCDSPGS302c   < VIP lives here
>> >
>> > FATAL:  failed to read kind from backend
>> > DETAIL:  kind mismatch among backends. Possible last query was: ...
>> > HINT:  check data consistency among db nodes
>> >
>> > The last query is in the first attached text file, along with pool node
>> and
>> > db streaming stats.  It's happening about 20 times per hour.
>> >
>> > (Load balancing is turned off.)
>> >
>> > The only other example of this error is when someone ran pg_dump through
>> > pgpool.
>> >
>> > What could be causing this?
>>
>> To find the cause I need more log for pid 1119834 before the FATAL error
>> happend.
>>
>
> Attachment sent directly to you,  But I found this just above the error
>
> WARNING:  packet kind of backend 1 ['Z'] does not match with main/majority
> nodes packet kind ['2']
>
> Note: many other processes were successfully connecting, and doing work.
> This error happens 10-20 times per hour.
>

Last week, I disabled load balancing, but the replica still has some weight
Might that be causing the problem?
load_balance_mode = off
backend_weight0 = 2
backend_weight1 = 1

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