Re: [SQL] plan not correct?

On 03/21/2016 08:29 AM, Bert wrote:

My mistake, Cced wrong list.

> That is easy to check.
>
> Let's do the same test again:
> # select count(1) from dlp.st_itemseat;
> count
> -------
> 12
> (1 row)
>
> # select count(1) from loaddlp.st_itemseat_insert;
> count
> -------
> 87 --> of which 12 are already in the dlp.st_itemseat table
> (1 row)
>
> # explain analyze <upsert query>*
> QUERY PLAN
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------
> Insert on st_itemseat (cost=55.47..69.97 rows=150 width=228) (actual
> time=2.345..2.345 rows=0 loops=1)
> CTE upsert
> -> Update on st_itemseat et (cost=17.50..55.42 rows=2 width=240)
> (actual time=0.493..0.545 rows=12 loops=1)
> -> Hash Join (cost=17.50..55.42 rows=2 width=240) (actual
> time=0.303..0.318 rows=12 loops=1)
> Hash Cond: ((et.tick_server_id =
> st_itemseat_insert_1.tick_server_id) AND (et.itemseat_id =
> st_itemseat_insert_1.itemseat_id))
> -> Seq Scan on st_itemseat et (cost=0.00..13.10
> rows=310 width=14) (actual time=0.025..0.028 rows=12 loops=1)
> -> Hash (cost=13.00..13.00 rows=300 width=234)
> (actual time=0.244..0.244 rows=87 loops=1)
> Buckets: 1024 Batches: 1 Memory Usage: 13kB
> -> Seq Scan on st_itemseat_insert
> st_itemseat_insert_1 (cost=0.00..13.00 rows=300 width=234) (actual
> time=0.005..0.120 rows=87 loops=1)
> -> Seq Scan on st_itemseat_insert (cost=0.04..14.54 rows=150
> width=228) (actual time=0.637..0.726 rows=75 loops=1)
> Filter: (NOT (hashed SubPlan 2))
> Rows Removed by Filter: 12
> SubPlan 2
> -> CTE Scan on upsert (cost=0.00..0.04 rows=2 width=8)
> (actual time=0.498..0.561 rows=12 loops=1)
> Planning time: 1.122 ms
> Execution time: 2.682 ms
>
> # <upsert query>*
> INSERT 0 0
>
> # select count(1) from dlp.st_itemseat;
> count
> -------
> 87
> (1 row)
>
>
> * the upsert query can be found attached to the first mail, but the
> difference is that the 'where loadtabletime' is removed
>
> As you can see the in the update part of the explain the 'rows' nr is
> 12. Which is what is expected.
> But the rows on the insert are again 0, while it should be 75.
>
> wkr,
> Bert
>
> On Mon, Mar 21, 2016 at 4:01 PM, Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>> wrote:
>
> 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(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
> <mailto:adrian(dot)klaver(at)aklaver(dot)com
> <mailto:adrian(dot)klaver(at)aklaver(dot)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> <tel:0477%2F305361>
>
>
>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
> <mailto:adrian(dot)klaver(at)aklaver(dot)com
> <mailto:adrian(dot)klaver(at)aklaver(dot)com>>
>
>
>
>
> --
> Bert Desmet
> 0477/305361 <tel:0477%2F305361>
>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>
>
>
>
> --
> Bert Desmet
> 0477/305361

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com