[CALCITE-4354] Allow ITEM operator on ROW/STRUCT data types

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.27.0
• Fix Version/s: 1.27.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Alessandro Solimando
• Reporter: Alessandro Solimando
• Created: 24/Oct/20 18:07
• Updated: 05/Jul/23 19:00
• Resolved: 30/Oct/20 10:06

Description

The current implementation of the "ITEM" operator cannot be apply to row/struct type.

The idea is to extend "ITEM" to support a signature "<ROW>[<CHARACTER|INTEGER>]", allowing to access elements by their position (1-based index), or their name (if available).

 

The current implementation supports an SQL query as follows:

select au."birthPlace"."city" as city from "bookstore"."authors" au;

  

The extended implementation will also support the following equivalent query:

select au."birthPlace"['city'] as city from "bookstore"."authors" au;

 

And since we have that "birthPlace(coords, city, country)", we can also access "city" with its index 2: 

select au."birthPlace"[2] as city from "bookstore"."authors" au;

 

Issue Links

• is related to: CALCITE-4436 Use the fields order from the struct type for 'ITEM(STRUCT, INDEX)' access
• relates to: CALCITE-4293 cassandra adapter returns null when selecting non-null tuple elements
• relates to: CALCITE-5701 Add NAMED_STRUCT function (enabled in Spark library)
• links to: GitHub Pull Request #2230
• links to: GitHub Pull Request #2267