Re: nextval() on serial using old, existing value on insert?

On Thu, May 11, 2023 at 1:07 AM Wells Oliver <wells(dot)oliver(at)gmail(dot)com> wrote:

> As a follow up, I've selected max(common_key) from the table and
> setval()'ed on the sequence to that +1 and I think that should make this go
> away. Any reason why that's insane?
>
> On Wed, May 10, 2023 at 10:02 PM Wells Oliver <wells(dot)oliver(at)gmail(dot)com>
> wrote:
>
>> Ah, I think that must be it-- there are 200 some rows where manually
>> supplied values for that common_key column are higher than the nextval() on
>> the serial. So eventually they might be "re-used".
>>
>> On Wed, May 10, 2023 at 9:55 PM David G. Johnston <
>> david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>>
>>>
>>> On Wednesday, May 10, 2023, Wells Oliver <wells(dot)oliver(at)gmail(dot)com> wrote:
>>>
>>>> I have a simple table with a given column defined like so:
>>>>
>>>> common_key | integer | | not null |
>>>> nextval('alias.identity_common_key_seq'::regclass) | plain
>>>>
>>>> Very very very infrequently, on an INSERT where this column is not
>>>> specified, this column will be assigned a value that already exists in the
>>>> table, versus the next presumably unused value in the sequence. I cannot
>>>> figure this out. Is there any reason why this might be the case?
>>>>
>>>
>>> Most likely someone inserted data without using the sequence and
>>> eventually the sequence catches up with that previously inserted data.
>>>
>>> David J.
>>>
>>>
>>
> --
> Wells Oliver
> wells(dot)oliver(at)gmail(dot)com <wellsoliver(at)gmail(dot)com>
>

That will make it go away for the values currently in the table, but does
nothing to prevent it happening again in the future.

Keith