+1 This is a valuable and most required feature. It makes Doris a fully
qualified SQL supported data warehouse DB.
On Wed, Jan 20, 2021 at 1:57 AM 王博 <506340...@qq.com> wrote:
> I think the desgin ideas is weird;
> Why update statement should be converted into a query and insert statement?
> As far as I know, Kudu support update api.
> Why not research Kudu's design first?
> I prefer to design from the perspective of the storage engine
>
>
>
>
> ------------------ 原始邮件 ------------------
> 发件人:
> "dev"
> <
> yangz...@gmail.com>;
> 发送时间: 2021年1月20日(星期三) 下午3:14
> 收件人: "dev"<dev@doris.apache.org>;
>
> 主题: Doris UNIQUE table supports UPDATE syntax
>
>
>
> ## Background
>
> The current Doris table does not support the update operation, but there
> are many scenarios where the data needs to be updated. Due to the batch
> delete function we implemented before, it paved the way for the update.
>
> ## Syntax
>
> We only support single table update
>
> ```
> UPDATE table_name
> SET assignment_list
> [WHERE where_condition]
> [ORDER BY...]
> [LIMIT row_count]
>
> value:
> {expr | DEFAULT}
>
> assignment:
> col_name = value
>
> assignment_list:
> assignment [, assignment].
> ```
>
> ## Design
>
> There are two kinds of updates involved here, one that only contains the
> value column, and the other that contains the key column.
>
> * Include and update of value column
>
> This method is relatively simple. You only need to plan the update
> statement into a query plan like `select * from table insert into table`
> during query planning, and you need to add an update node to modify the
> data to the updated value, or plan Into a statement similar to `select a,
> b,'xx','xx1' from table insert into table` and hand it directly to the
> tableSink node
>
> * Contains the update of the key column
>
> This kind of relatively complicated, we need to divide the query
> into two
> parts, and need to use the MERGE semantics in the batch delete, first plan
> it into a query plan similar to `select * from table insert into table`,
> and then generate it first for the modification of the key column One piece
> of data that needs to be deleted, and then replace the value of the key
> column to generate new data that needs to be added, mainly generating two
> pieces of imported data from one piece of original data. Need update node
> to have the ability to repeat data
>
> ## Subtasks
>
> 1. Add index to unique table value column to speed up data scanning
> 2. FE supports update statements and generates corresponding query plans.
> Be implements update node, which can be divided into two parts here
> 1. Support updates that only contain the value column
> 2. Support the update of the key column
