Hi Jingsong,
## The way to declare aggregate functions Considering possible sql parsing problem, I aggree with your idea. ## Supported functions It is better to keep consistent with Flink Table, which is more relevant with our project, and PostgreSQL, whose grammar is widely accepted. ## Default function && Changelog support I have update FLIP to illustrate the default value of correspongding agg function and its support for changelog/retraction messages [1]. [1] https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/concepts/dynamic_tables/ ------------------ ???????? ------------------ ??????: "dev" <jingsongl...@gmail.com>; ????????: 2022??8??3??(??????) ????5:14 ??????: "dev"<dev@flink.apache.org>; ????: Re: [Phishing Risk] [External] [DISCUSS] FLIP-255 Introduce pre-aggregated merge to Table Store Hi Nathan, Thanks for the reply. ## Aggregate functions I think `'fields.sum_field1.function'='sum'` is a safe one, I am more worried about using complex json, which will affect the sql parsing. ## Supported functions I think it is better to be consistent with Flink Table [1] and PostgreSQL [2]. - replace -> last_value - replace_if_not_null -> last_non_null_value - concatenate -> listagg - or -> bool_or - and -> bool_and ## Default function You can update the FLIP to clarify the default value of the corresponding agg function. ## Changelog support Can you also specify whether functions support changelog/retraction messages? [1] https://nightlies.apache.org/flink/flink-docs-release-1.15/docs/dev/table/functions/systemfunctions/#aggregate-functions [2] https://www.postgresql.org/docs/9.5/functions-aggregate.html Best, Jingsong On Tue, Aug 2, 2022 at 11:41 PM Hannan Kan <hannan...@foxmail.com> wrote: > > Thank you for reviewing FLIP-255. > > That indeed is a typo. I will correct it immediately. > > > Best, > Nathan > > > > > ------------------&nbsp;????????&nbsp;------------------ > ??????: "dev" <liguo...@bytedance.com&gt;; > ????????:&nbsp;2022??8??2??(??????) ????11:09 > ??????:&nbsp;"dev"<dev@flink.apache.org&gt;; > > ????:&nbsp;Re: [Phishing Risk] [External] [DISCUSS] FLIP-255 Introduce pre-aggregated merge to Table Store > > > > Hi Nathan, > > > Seems a great proposal for table store aggregation. > In the example, I think the 'max_field1' should be 1 instead of 2 after the max aggregation in the output result. > And there may be a minor typo in the WITH clause, 'max_field2' -&gt; 'max_field1'. > > > > Best, > Guojun > > > > From: "Hannan Kan"<hannan...@foxmail.com&gt; > Date: Mon, Aug 1, 2022, 11:35 PM > Subject: [Phishing Risk] [External] [DISCUSS] FLIP-255 Introduce pre-aggregated merge to Table Store > To: "dev"<dev@flink.apache.org&gt; > Cc: "lzljs3620320"<lzljs3620...@apache.org&gt; > > > > Hi everyone, I would like to open a discussion on&amp;nbsp;FLIP-255 Introduce pre-aggregated merge to table store&amp;nbsp;[1]. Pre-aggregation mechanism has been adopted by many big data systems (such as Apache Doris,&amp;nbsp; Apache Kylin , Druid etc.)&amp;nbsp;to save storage and accelerate the aggregate query. FLIP-255 proposes to introduce pre-aggregated merge into Flink Table Store to acquire the same benefit.&amp;nbsp; Supported aggregate functions include&amp;nbsp;sum, max/min, count, replace_if_not_null, replace,&amp;nbsp; concatenate, or/and. Looking forward to your feedback. [1]&amp;nbsp;https://cwiki.apache.org/confluence/display/FLINK/FLIP-255+Introduce+pre-aggregated+merge+to+table+store Best, Nathan Kan (Hongnan Gan)
