Joining by closest timestamp in PrestoDB












0














I have two large tables in a Presto db - calls and mobile_updates. Each mobile_id has multiple updates, each with a new software version.
Each call was made at a fixed timestamp call_started.



My objective is join the two by the closest (previous) created_at timestamp in mobile_updates to when the call was made, and by mobile_id to get the version at the time the call was made in Presto. The result should be two columns: call_started and version



The existing code for some reason does not produce the desired results - it only returns the most recent call for each mobile_id, whereas there should be multiple calls.



Subqueries are not supported in Presto, so that is why partitions must be used. What could be wrong?



with calls as (

SELECT
call_started
, mobile_id
from calls
)

, ranking as (
select
mu.mobile_id
, mu.version
, mu.created_at
, c.call_started
, rank() over (partition by mu.mobile_id order by mu.created_at desc) as rank

from mobile_updates mu
join calls c
on mu.mobile_id = c.mobile_id
where mu.created_at < c.call_started
)

select
call_started
,version
from ranking
where rank = 1









share|improve this question






















  • Sample data and desired results would help.
    – Gordon Linoff
    Nov 12 at 2:14










  • What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
    – Kamil Bajda-Pawlikowski
    Nov 13 at 18:33
















0














I have two large tables in a Presto db - calls and mobile_updates. Each mobile_id has multiple updates, each with a new software version.
Each call was made at a fixed timestamp call_started.



My objective is join the two by the closest (previous) created_at timestamp in mobile_updates to when the call was made, and by mobile_id to get the version at the time the call was made in Presto. The result should be two columns: call_started and version



The existing code for some reason does not produce the desired results - it only returns the most recent call for each mobile_id, whereas there should be multiple calls.



Subqueries are not supported in Presto, so that is why partitions must be used. What could be wrong?



with calls as (

SELECT
call_started
, mobile_id
from calls
)

, ranking as (
select
mu.mobile_id
, mu.version
, mu.created_at
, c.call_started
, rank() over (partition by mu.mobile_id order by mu.created_at desc) as rank

from mobile_updates mu
join calls c
on mu.mobile_id = c.mobile_id
where mu.created_at < c.call_started
)

select
call_started
,version
from ranking
where rank = 1









share|improve this question






















  • Sample data and desired results would help.
    – Gordon Linoff
    Nov 12 at 2:14










  • What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
    – Kamil Bajda-Pawlikowski
    Nov 13 at 18:33














0












0








0







I have two large tables in a Presto db - calls and mobile_updates. Each mobile_id has multiple updates, each with a new software version.
Each call was made at a fixed timestamp call_started.



My objective is join the two by the closest (previous) created_at timestamp in mobile_updates to when the call was made, and by mobile_id to get the version at the time the call was made in Presto. The result should be two columns: call_started and version



The existing code for some reason does not produce the desired results - it only returns the most recent call for each mobile_id, whereas there should be multiple calls.



Subqueries are not supported in Presto, so that is why partitions must be used. What could be wrong?



with calls as (

SELECT
call_started
, mobile_id
from calls
)

, ranking as (
select
mu.mobile_id
, mu.version
, mu.created_at
, c.call_started
, rank() over (partition by mu.mobile_id order by mu.created_at desc) as rank

from mobile_updates mu
join calls c
on mu.mobile_id = c.mobile_id
where mu.created_at < c.call_started
)

select
call_started
,version
from ranking
where rank = 1









share|improve this question













I have two large tables in a Presto db - calls and mobile_updates. Each mobile_id has multiple updates, each with a new software version.
Each call was made at a fixed timestamp call_started.



My objective is join the two by the closest (previous) created_at timestamp in mobile_updates to when the call was made, and by mobile_id to get the version at the time the call was made in Presto. The result should be two columns: call_started and version



The existing code for some reason does not produce the desired results - it only returns the most recent call for each mobile_id, whereas there should be multiple calls.



Subqueries are not supported in Presto, so that is why partitions must be used. What could be wrong?



with calls as (

SELECT
call_started
, mobile_id
from calls
)

, ranking as (
select
mu.mobile_id
, mu.version
, mu.created_at
, c.call_started
, rank() over (partition by mu.mobile_id order by mu.created_at desc) as rank

from mobile_updates mu
join calls c
on mu.mobile_id = c.mobile_id
where mu.created_at < c.call_started
)

select
call_started
,version
from ranking
where rank = 1






sql prestodb






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asked Nov 12 at 2:09









the_darkside

1,9471134




1,9471134












  • Sample data and desired results would help.
    – Gordon Linoff
    Nov 12 at 2:14










  • What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
    – Kamil Bajda-Pawlikowski
    Nov 13 at 18:33


















  • Sample data and desired results would help.
    – Gordon Linoff
    Nov 12 at 2:14










  • What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
    – Kamil Bajda-Pawlikowski
    Nov 13 at 18:33
















Sample data and desired results would help.
– Gordon Linoff
Nov 12 at 2:14




Sample data and desired results would help.
– Gordon Linoff
Nov 12 at 2:14












What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
– Kamil Bajda-Pawlikowski
Nov 13 at 18:33




What do you mean by "Subqueries are not supported in Presto"? I know many TPC-DS queries include complex subqueries and Presto is able to execute all of them. Could you please show us a subquery that did not work for you? Also, what's the version of Presto you are using?
– Kamil Bajda-Pawlikowski
Nov 13 at 18:33

















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