[jira] [Commented] (IGNITE-15784) Support custom mapping for fields and column of arbitrary types.

["Yury Gerzhedovich (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-15784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17458999#comment-17458999 ] 

Yury Gerzhedovich commented on IGNITE-15784:
--------------------------------------------

[~amashenkov] , LGTM in general. Let's add JIRA links for TODOs and may be we should think out the possibility ignore case mode for column names at mappers (as a separate ticket).

> Support custom mapping for fields and column of arbitrary types.
> ----------------------------------------------------------------
>
>                 Key: IGNITE-15784
>                 URL: https://issues.apache.org/jira/browse/IGNITE-15784
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>            Reporter: Andrey Mashenkov
>            Assignee: Andrey Mashenkov
>            Priority: Major
>              Labels: ignite-3
>             Fix For: 3.0.0-alpha4
>
>          Time Spent: 2h 10m
>  Remaining Estimate: 0h
>
> h3. Motivation.
> A user may want to operate with user objects, which types may differ from or incompatible with a column type.
> As a special case, a user may want to transparently serialize an arbitrary object to byte[] (BLOB) column.
> h3. Description.
> To achieve this we can provide an interface for the converter and allow passing custom converters to a mapper.
> The converter acts as an interceptor and transforms a value before writing to/after reading from the column.
> Mapper API should be refactored as well to support this.
> As a PoC, let's add a test with a converter that performs transparent Java serialization arbitrary object to byte[] column.
> Converters and automatic typecasting is out of the scope,
> the goal is to create API and infrastructure for further extension, e.g.
> * provide a standard converter component for cross-platform  serialization (based on MessagePack or on IGNITE-15944 ticket ideas)
> * optionally add JSON/BSON format support.
> * add simple converters for supported native types, e.g. Integer<-->String, and possibly, support implicit typecasting.
> * support unsigned types via implicit typecasting mechanics.



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