[CALCITE-4436] Use the fields order from the struct type for 'ITEM(STRUCT, INDEX)' access

• 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: 10/Dec/20 17:37
• Updated: 05/Jul/23 19:00
• Resolved: 17/Dec/20 14:17

Description

The index-based access via the "ITEM" operator for operands of row/struct type is currently experimental and disabled by default (introduced in CALCITE-4354).

Its implementation uses the fields order from `getDeclaredFields()`, a JVM-specific feature, this might lead to silent data corruption (see PR-2230).

The aim of the ticket is to improve the feature by relying on the safer fields order
from the struct field type itself (i.e., `relType.getFields()[index]`) so that we can enable it by default.

Issue Links

• relates to: CALCITE-5701 Add NAMED_STRUCT function (enabled in Spark library)
• relates to: CALCITE-4354 Allow ITEM operator on ROW/STRUCT data types
• links to: GitHub Pull Request #2296