confluentinc/ksql

Convert a MAP to ARRAY with ENTRIES()

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#5,452 opened on May 21, 2020

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 (2 comments) (0 reactions) (0 assignees)Java (5,739 stars) (1,048 forks)batch import
enhancementhelp wanted

Description

I have data in the style of {"a":1, "b":{"b1": {"c":"aaa", "d":"bbb"}, "b2": {"c":"ccc", "d":"ddd"}}}

With schema defined as

a INT,
b MAP<STRING, STRUCT<
  c STRING,
  d STRING
>>

I would like to convert it to

a INT,
b ARRAY<STRUCT<
  c STRING,
  d STRING
>>

To look like this {"a":1, "b":[{"c":"aaa", "d":"bbb"},{"c":"ccc", "d":"ddd"}]}

Currently using ENTRIES() returns

Function 'ENTRIES' does not accept parameters (MAP<STRING, STRUCT<C STRING, D STRING>>).
Valid alternatives are:
ENTRIES(MAP<STRING, DOUBLE> map, BOOLEAN sorted)
ENTRIES(MAP<STRING, BOOLEAN> map, BOOLEAN sorted)
ENTRIES(MAP<STRING, VARCHAR> map, BOOLEAN sorted)
ENTRIES(MAP<STRING, BIGINT> map, BOOLEAN sorted)
ENTRIES(MAP<STRING, INT> map, BOOLEAN sorted)

Could ENTRIES() be extended to support this scenario?

Contributor guide

Tech stack
javasql
Domain
database
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Java programmingksql function developmentSQL data types
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Start by examining the current implementation of the ENTRIES function in the ksql codebase, likely in the `ksql functions` module. Look for existing overloads that accept `MAP<STRING, DOUBLE>` etc. The error message shows the supported types. Extend by adding a new overload that accepts `MAP<STRING, STRUCT<...>>` and returns an array of structs. Check the comments on the issue for any additional context or guidance from maintainers.