Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

PS , in the meanwhile I discovered a 2nd workaround(beside disabling
parallel processing) . I added offset 0 to the subquery , and, according
to the documentation, “OFFSET 0 is the same as omitting the OFFSET clause” -
https://www.postgresql.org/docs/current/static/queries-limit.html

cmd3dev=# show max_parallel_workers_per_gather ;

*max_parallel_workers_per_gather*

*---------------------------------*

*8*

(1 row)

cmd3dev=# \timing

Timing is on.

cmd3dev=# SELECT * FROM (SELECT seg.circuit_id AS id,
vendor_gtt_pop.vendor_id, CASE WHEN vendor_gtt_pop.push_to_gaa = 1 THEN 'Y'
END as gaa, pop.gii_circuitid AS pop_name, cst.label AS pop_status,
seg.a_company_name AS pop_location, seg.vendor_id AS pop_provider_id,
seg.vendor_name AS pop_provider, cs.address1 AS pop_street, cs.city AS
pop_city, cs.postal_code AS pop_postal_code, cs.state AS pop_state,
csc.code AS pop_country, cs.country_id AS pop_country_id FROM ( SELECT
c.gii_circuitid, max(so.id) AS service_order_id FROM service_order so join
circuit c on c.product_id=so.product_id join master_service_order mso on
mso.id=so.master_service_order_id WHERE NOT (so.ordertype_id = 2 AND
so.status <> 999) AND NOT (so.ordertype_id = 3 AND so.status <> 999) AND
c.status >= 20 AND c.status not in (160,999) AND mso.client_id=11615 AND
c.service_description=28 AND c.status!=160 GROUP BY c.gii_circuitid ) pop
JOIN service_order so ON so.id = pop.service_order_id left JOIN client_site
cs on cs.id=so.a_site_id left JOIN country csc on csc.id=cs.country_id JOIN
circuit c ON so.product_id=c.product_id JOIN circuit_status cst ON
cst.id=c.status
JOIN ( SELECT c.id AS circuit_id, sg.id AS segment_id,
c.pop_support_vendor_id AS vendor_id, v.name AS vendor_name,
sg.a_company_name FROM segment sg JOIN circuit_layout cl ON cl.segment_id =
sg.id AND cl.ordinal = 1 JOIN circuit c ON c.id = cl.circuit_id JOIN vendor
v ON v.id = c.pop_support_vendor_id ) seg ON seg.circuit_id = c.id JOIN
vendor_gtt_pop on vendor_gtt_pop.gtt_pop_id = seg.circuit_id offset 0) foo
where vendor_id = 12346 AND (1=1) ORDER BY pop_name ASC,id desc LIMIT 10;

id | vendor_id | gaa | pop_name | pop_status | pop_location |
pop_provider_id | pop_provider | pop_street | pop_city | pop

_postal_code | pop_state | pop_country | pop_country_id

--------+-----------+-----+---------------+------------+--------------+-----------------+--------------+---------------------+----------+----

-------------+-----------+-------------+----------------

684807 | 12346 | Y | GTT/POP/LON1T | Active | LON1T
| 12288 | Telehouse UK | 14 Coriander Avenue | London | E14

2AA | | GB | 219

(1 row)

*Time: 2245.073 ms (00:02.245)*

On Fri, Mar 23, 2018 at 9:31 AM, Alessandro Aste <alessandro(dot)aste(at)gmail(dot)com>
wrote:

> Tomas, I'm attaching a 4MB file with the perf report. Let me know if it
> gets blocked, I'll shrink it to the first 1000 lines.
>
> Thank you,
>
> Alessandro.
>
> On Thu, Mar 22, 2018 at 11:42 PM, Tomas Vondra <
> tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>
>> On 03/22/2018 11:29 PM, Alessandro Aste wrote:
>> > Thanks Tomas. We're currently building postgres from source. In order to
>> > enable symbols, you want me to re-configure postres with --enable-debug
>> > then run perf?
>> >
>>
>> Yes.
>>
>> regards
>>
>> --
>> Tomas Vondra http://www.2ndQuadrant.com
>> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>>
>
>