[
https://issues.apache.org/jira/browse/IGNITE-4750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16283710#comment-16283710
]
Taras Ledkov commented on IGNITE-4750:
--------------------------------------
[~vozerov], [~al.psc], [~skalashnikov] I need in primary review for the patch.
Please take a look.
I guess tow ways to support GROUP_CONCAT in not collocated mode is
1. Use our own aggregate functions for map and reduce query. On map step:
accumulates values in collection and returns collection. On reduce step:
accumulates map's collection in reduce collection and returns sorted /
distinct.
The problem is complex {{ORDER BY}} expression inside {{GROUP_CONCAT}} function.
2. Use H2 {{GROUP_CONCAT}} function on reduce step and not-aggregated select
for map step.
The problem: query can support other aggregate functions.
> SQL: Support GROUP_CONCAT function
> ----------------------------------
>
> Key: IGNITE-4750
> URL: https://issues.apache.org/jira/browse/IGNITE-4750
> Project: Ignite
> Issue Type: Task
> Components: sql
> Reporter: Denis Magda
> Assignee: Taras Ledkov
>
> GROUP_CONCAT function is not supported at the moment. Makes sense to fill
> this gap:
> http://apache-ignite-users.70518.x6.nabble.com/GROUP-CONCAT-function-is-unsupported-td10757.html
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
