[IGNITE-9616] SQL: Introduce H2 factory for holder of aggregate result

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.6
• Component/s: sql
• Labels: h2-limitation
• Ignite Flags: Docs Required
• Assignee: Unassigned
• Reporter: Taras Ledkov
• Created: 17/Sep/18 12:42
• Updated: 01/Oct/19 03:08

Description

H2 collects aggregate results at the simple HashMap (groups set and values set).
This causes an OOME error on large groups set and large group size with DISTINCT.

We have to introduce way to use our own implementation of the aggregate result's container.

H2 issue: #1433

Issue Links

• relates to: IGNITE-9480 SQL: Introduce H2 LocalResult factory
• relates to: IGNITE-7526 SQL: Introduce memory region for reducer merge results with disk offload
• links to: H2 Issue #1433