Search Postgresql Archives

Re: mysql_fdw trouble

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 10/30/2015 09:55 AM, Dane Foster wrote:
On Fri, Oct 30, 2015 at 12:52 PM, Adrian Klaver
<adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>> wrote:

    On 10/30/2015 09:36 AM, Dane Foster wrote:

        On Fri, Oct 30, 2015 at 12:26 PM, Adrian Klaver
        <adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>
        <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>> wrote:

             On 10/30/2015 08:13 AM, Dane Foster wrote:


                 On Fri, Oct 30, 2015 at 10:57 AM, Adrian Klaver
                 <adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
        <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>> wrote:

                      On 10/30/2015 07:21 AM, Dane Foster wrote:


                          On Fri, Oct 30, 2015 at 9:40 AM, Adrian Klaver
                          <adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>
                          <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>

                          <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>>> wrote:

                               On 10/29/2015 05:38 PM, Dane Foster wrote:

                                   Hello,

                                   I think I've tripped over another
        mysq_fdw
                 bug. I've
                          filed a bug
                                   report
                                   on github already but just in case
        the problem
                 is w/ my
                          query I
                                   figured
                                   I would post it here in case someone sees
                 something
                          obvious.

                                   The error message I get is: null
        value in column
                          "location" violates
                                   not-null constraint.

                                   The DDL is here:
        https://github.com/EnterpriseDB/mysql_fdw/issues/71

                                   For the record I know top posting is
        a crime
                 against
                          god and
                                   humanity
                                   but I feel justified because this
        post is not
                 directly
                          related
                                   to the
                                   original. So there!  Granted it's in
        the same
                 milieu;
                          and yes this
                                   current sentence exists for the sole
        purpose of me
                          being able to
                                   use the
                                   word milieu because the opportunity
        to use it
                 is so few
                          and far
                                   between.

                                   ​INSERT INTO series (cid, day, title,
        description,
                          location,
                                   duration,
                                   can_join)
                                       SELECT
                                         cid,
                                         row_number() OVER (PARTITION BY
        cid ORDER BY
                          lower(duration)),
                                         title,
                                         description,
                                         location,
                                         duration,
                                         can_join
                                       FROM (
                                         SELECT
                                           cid,
                                           title,
                                           description,
                                           can_join::BOOLEAN,
                                           (SELECT label FROM _locations
        WHERE
                          loc=location) AS
                                   location,
                                           ('[' || starts || ', ' ||
        (starts +
                 INTERVAL '4
                          HOUR') ||
                                   ']')::TSZ_PERIOD AS duration
                                         FROM
                                           _series
                                       ) AS v​

                                   ​Regards,​


                               So what do you get when you do?:

                               SELECT
                                      cid,
                                      title,
                                      description,
                                      can_join::BOOLEAN,
                                      (SELECT label FROM _locations WHERE
                 loc=location) AS
                          location,
                                      ('[' || starts || ', ' || (starts
        + INTERVAL '4
                          HOUR') ||
                               ']')::TSTZRANGE AS duration
                                    FROM
                                      _series
                                  );


                                   Dane




                               --
                               Adrian Klaver
        adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>
        <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>
                          <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>

                          <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>>

                          ​
                          I get rows of data, location and all.


                      And when you do?:

                      SELECT
                           cid,
                           row_number() OVER (PARTITION BY cid ORDER BY
                 lower(duration)),
                           title,
                           description,
                           location,
                           duration,
                           can_join
                         FROM (
                           SELECT
                             cid,
                             title,
                             description,
                             can_join::BOOLEAN,
                             (SELECT label FROM _locations WHERE
        loc=location) AS
                 location,
                             ('[' || starts || ', ' || (starts + INTERVAL '4
                 HOUR') ||
                      ']')::TSTZRANGE AS duration
                           FROM
                             _series
                         ) AS v



                          Dane
                          ​



                      --
                      Adrian Klaver
        adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>
        <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>
                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>

                 <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>>


                 ​Before I answer your second query question I need to
        revise my
                 response
                 to the first. Yes the first query runs w/o an error
        message but
                 the bit
                 about "rows and all" was not entirely correct. Out of
        313 rows
                 only the
                 first row had a location. The other 312 rows have NULL
        in the
                 location
                 column which is not supposed to happen. To verify this
        I changed the
                 table names and removed the PostgreSQL transformations
        (i.e.,
                 use of ||
                 and :: for casting) and ran the query against the MySQL
        database; it
                 returned 313 rows of data, location and all.


             You would think that would also cause an issue with the
        first row
             that is returned correctly. My suspicion is with this:

             row_number() OVER (PARTITION BY cid ORDER BY lower(duration))

             What happens if you run the full SELECT without it?




                 Now that I've cleared that up.

                 Your second query also runs w/o any error messages but
        like the
                 first
                 only the first row has a non NULL value in the location
        column.



                 Dane
                 ​



             --
             Adrian Klaver
        adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>
        <mailto:adrian.klaver@xxxxxxxxxxx
        <mailto:adrian.klaver@xxxxxxxxxxx>>

        ​
        Your first query didn't use it and as discussed rows come back
        but only
        the first row has a non NULL location column.


    Forgot about that. Where I was going with this is that duration
    comes from:

    ('[' || starts || ', ' || (starts + INTERVAL '4 HOUR') ||
    ']')::TSTZRANGE AS duration

    and MySQL and Postgres have different ideas about timestamps. While
    I thinking about what that meant in the context of the query I
    realized I was stepping over the obvious:

    SELECT label FROM _locations WHERE loc=location

    So what does the below show:

    SELECT label FROM _locations, _series WHERE loc=location;



        Dane
        ​



    --
    Adrian Klaver
    adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>

​
It returns all the locations.

You know where we are going:

SELECT label, starts, ('[' || starts || ', ' || (starts + INTERVAL '4 HOUR') || ']')::TSTZRANGE AS duration FROM _locations, _series WHERE loc=location;



Dane
​



--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx


--
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux