Re: [SQL] plan not correct?

On 03/21/2016 07:54 AM, Bert wrote:

Ccing list

Hello Ardian,

The PostgreSQL version is 9.4.5

The reason I have the 'returning' statement in the update section is
because I only insert the data that has not been updated. I don't see
why I would need to return anything in the insert section?

Well it was more about what you saw as the result of the UPDATE. It is not clear to me whether that is 'UPDATE count' or the rows from RETURNING?

On Mon, Mar 21, 2016 at 3:39 PM, Adrian Klaver

<adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:

    On 03/21/2016 07:03 AM, Bert wrote:

        Dear all,

        I am not sure if I am looking at a bug, or I am just doing
        something wrong.
        Anyhow, to me it seems that the plan for an upsert is wrong. (I
        can not
        find how many rows are inserted in the table)

        Regard the following setup:
        # select count(1) from dlp.st_itemseat;
           count
        -------
               0
        (1 row)

        # select count(1) from loaddlp.st_itemseat_insert where
        loadtabletime =
        '2016-03-21 14:53:28.771467';
           count
        -------
              12
        (1 row)

        # explain analyze <upsert query>*

        QUERY PLAN
        ---------------------------------------------------------------------------------------------------------------------------------------------------------
           Insert on st_itemseat  (cost=26.14..41.39 rows=1 width=228)
        (actual
        time=1.282..1.282 rows=0 loops=1)
             CTE upsert
               ->  Update on st_itemseat et  (cost=0.15..26.11 rows=1
        width=240)
        (actual time=0.066..0.066 rows=0 loops=1)
                     ->  Nested Loop  (cost=0.15..26.11 rows=1
        width=240) (actual
        time=0.061..0.061 rows=0 loops=1)
                           ->  Seq Scan on st_itemseat_insert
        st_itemseat_insert_1  (cost=0.00..13.75 rows=2 width=234) (actual
        time=0.031..0.040 rows=12 loops=1)
                                 Filter: (loadtabletime = '2016-03-21
        14:53:28.771467'::timestamp without time zone)
                                 Rows Removed by Filter: 75
                           ->  Index Scan using pk_st_itemseat on
        st_itemseat et
        (cost=0.15..6.17 rows=1 width=14) (actual time=0.001..0.001
        rows=0 loops=12)
                                 Index Cond: ((tick_server_id =
        st_itemseat_insert_1.tick_server_id) AND (itemseat_id =
        st_itemseat_insert_1.itemseat_id))
             ->  Seq Scan on st_itemseat_insert  (cost=0.02..15.27 rows=1
        width=228) (actual time=0.175..0.201 rows=12 loops=1)
                   Filter: ((loadtabletime = '2016-03-21
        14:53:28.771467'::timestamp without time zone) AND (NOT (hashed
        SubPlan 2)))
                   Rows Removed by Filter: 75
                   SubPlan 2
                     ->  CTE Scan on upsert  (cost=0.00..0.02 rows=1
        width=8)
        (actual time=0.068..0.068 rows=0 loops=1)
           Planning time: 1.022 ms
           Execution time: 1.596 ms
        (16 rows)


        # <upsert query>*
        INSERT 0 0

        # select count(1) from dlp.st_itemseat;
           count
        -------
              12
        (1 row)

        * the upsert query is added as an attachment to this mail.


        In the query plan it seems that 0 rows are inserted; although 12
        rows
        are inserted when we compare the 2 counts.
        When an update happens, the rows reported in the 'update'
        statement are
        correct.


    Do you get a row count or the rows?

    The reason I ask is that in the UPDATE section you have
    '...returning ET.*', but not in the INSERT section.

    Not sure if it matters in this case, but the Postgres version might
    provide context.



        Is this a bug? Or am I looking at the wrong part of the plan? I
        would
        like to check how many rows are actually inserted from the plan.

        wkr,
        Bert

        --
        Bert Desmet

        0477/305361 <tel:0477%2F305361>





    --
    Adrian Klaver
    adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>




--
Bert Desmet
0477/305361

--
Adrian Klaver
adrian.klaver@aklaver.com