I was able to get sequel_pg running on my local and got the same output you
did. Interesting that I am not able to reproduce.
Setting ENV["NO_SEQUEL_PG"] = "true" in the testing environment I *was*
still able to to reproduce...
Could this be at the level of the operating system?
My system uses: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a)
[x86_64-darwin21]
But the system where I can reproduce has ruby 3.1.2p20 (2022-04-12 revision
4491bb740a) [x86_64-linux]
On Tuesday, September 27, 2022 at 6:27:21 PM UTC-4 Charlie Pham wrote:
> To add,
>
> I ran the following script on a test environment (non-local) and was able
> to reproduce the issue:
>
> DB.create_table(:foo){Integer :id; Time :t}
> ds = DB[:foo]
> ds.insert(1, '2021-11-07 01:35:44.443726')
> ds.insert(2, '2022-02-21 08:22:37.146317')
> ds.insert(3, '2021-03-23 08:36:22.655691')
> p ds.where(id: 1).get(:t)
> p ds.where(id: 2).get(:t)
> p ds.where(id: 1).get(:t)
> p ds.where(id: 3).get(:t)
> p ds.where(id: 1).get(:t)
>
> *2021-11-07 01:35:44.443726 -0700*
> 2022-02-21 08:22:37.146317 -0800
> *2021-11-07 01:35:44.443726 -0800*
> 2021-03-23 08:36:22.655691 -0700
> *2021-11-07 01:35:44.443726 -0700*
>
> I will try to figure out what the difference between my test environment
> and local environment is
> On Tuesday, September 27, 2022 at 6:03:10 PM UTC-4 Charlie Pham wrote:
>
>> Ah, shoot.
>>
>> I'm unable to reproduce this on my local database but am able to
>> reproduce it in another setting.
>>
>> When trying to monkey patch on my local with the following code:
>>
>> module Sequel
>> module Postgres
>> class Dataset
>>
>> def fetch_rows(sql)
>> return cursor_fetch_rows(sql){|h| yield h} if @opts[:cursor]
>> execute(sql) do |res|
>> cols = fetch_rows_set_cols(res)
>> *puts cols*
>> yield_hash_rows(res, cols) do |h| yield h
>> end
>> end
>> end
>> end
>> end
>> end
>>
>> The bolded line correctly puts out #<Method:
>> Sequel::Postgres::Database(Sequel::Database)#to_application_timestamp(v)
>> /Users/charliepham/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/sequel-5.60.1/lib/sequel/database/misc.rb:311>
>>
>>
>> Which always returns that consistent value.
>>
>> When I run it on the environment that has the issue, `cols` is actually
>> nil! I thought that it was `pg_sequel` that was overwriting these methods
>> (fetch_rows_set_cols, yield_hash_rows, etc.). Is that correct? Or perhaps
>> there's another plugin I'm neglecting...
>> On Tuesday, September 27, 2022 at 5:27:34 PM UTC-4 Jeremy Evans wrote:
>>
>>> On Tue, Sep 27, 2022 at 2:08 PM 'Charlie Pham' via sequel-talk <
>>> [email protected]> wrote:
>>>
>>>> Hello,
>>>>
>>>> I have a model that has a field `created_at` that is of type timestamp
>>>> without timezone in Postgres. All of the relevant timezone settings are
>>>> set
>>>> to `:local`. We are in PST (-8) and PDT (-7).
>>>>
>>>> I am running into an issue that I believe stems from `pg_sequel` that
>>>> results in an ambiguous (during the hour where daylight savings ends) time
>>>> value in Ruby flip-flopping between the -7 and -8 timezones.
>>>>
>>>> Observe the behaviour here:
>>>> *Model**[132639966].changed_at => 2021-11-07 01:35:44.443726 -0700 *
>>>> Model[150890643].changed_at => 2022-02-21 08:22:37.146317 -0800
>>>> *Model**[132639966].changed_at => 2021-11-07 01:35:44.443726 -0800*
>>>> Model.first.changed_at => 2021-03-23 08:36:22.655691 -0700
>>>> *Model**[132639966].changed_at
>>>> => 2021-11-07 01:35:44.443726 -0700*
>>>>
>>>> It appears that whether the -7 or -8 appears depends on the last
>>>> encountered value (see the previous lines). Repeating any of the bold
>>>> lines
>>>> sequentially yields the same result, but running any of the non-bolded
>>>> lines immediately changes the bold lines' outputs to match the timezone of
>>>> the non-bolded lines.
>>>>
>>>> I believe the source of this is pg_sequel since patching the vanilla
>>>> `fetch_rows_set_cols` and `yield_hash_rows` results in consistent
>>>> behaviour
>>>> (always -8)
>>>> *Model[132639966].changed_at => 2021-11-07 01:35:44.443726 -0800*
>>>> Model[150890643].changed_at => 2022-02-21 08:22:37.146317 -0800
>>>> *Model**[132639966].changed_at => 2021-11-07 01:35:44.443726 -0800*
>>>> Model.first.changed_at => 2021-03-23 08:36:22.655691 -0700
>>>> *Model**[132639966].changed_at => 2021-11-07 01:35:44.443726 -0800*
>>>>
>>>> I tried looking at the source code for handling timestamp columns in
>>>> the c code but can't figure it out.
>>>>
>>>> Best,
>>>> Charlie
>>>>
>>>
>>> Charlie,
>>>
>>> Are the underlying columns timestamp or timestamptz (timestamp with
>>> timezone)? If they are timestamp and not timestamptz, they are stored in
>>> local time, and local time uses daylight savings time, then the underlying
>>> values are ambiguous. Why exactly they flip-flop, I'm not sure, but in any
>>> case, the result would not be considered a bug as the underlying values are
>>> ambiguous.
>>>
>>> Is this issue specific to sequel_pg? If you run sequel without
>>> sequel_pg (NO_SEQUEL_PG in the environment will disable the use of
>>> sequel_pg), do you get consistent results? I'm not seeing anything
>>> specific in sequel_pg that would cause this, but maybe it is using a Ruby
>>> C-API that does this (rb_time_timespec_new maybe?).
>>>
>>> If you could submit a minimal self contained example showing this issue,
>>> that would significantly speed up debugging. Something like:
>>>
>>> DB.create_table(:foo){Integer :id; Time :t}
>>> ds = DB[:foo]
>>> ds.insert(1, '*2021-11-07 01:35:44.443726*')
>>> ds.insert(2, ' 2022-02-21 08:22:37.146317')
>>> p ds.where(id: 1).get(:t)
>>> p ds.where(id: 2).get(:t)
>>> p ds.where(id: 1).get(:t)
>>>
>>> That example doesn't show the issue in my environment, though:
>>>
>>> 2021-11-07 01:35:44 -0700
>>> 2022-02-21 08:22:37 -0800
>>> 2021-11-07 01:35:44 -0700
>>>
>>> Does it show the issue in your environment? If not, hopefully you can
>>> modify it so that it does show the issue.
>>>
>>> Thanks,
>>> Jeremy
>>>
>>
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