[IMPALA-4865] Limit size of literal values from constant folding

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.8.0
• Fix Version/s: Impala 3.3.0
• Component/s: Frontend
• Labels: newbie
• Target Version: Product Backlog
• Assignee: Fang-Yu Rao
• Reporter: Henry Robinson
• Created: 01/Feb/17 23:56
• Updated: 21/Jun/19 22:15
• Resolved: 21/Jun/19 22:15

Description

Consider (from test_insert.py) the following query:

create table foo as select repeat('AZ', 128 * 1024 * 1024) as s

repeat() gets constant-folded into a 256MB expression payload, which is then transmitted to every fragment instance that evaluates the expression. This can lead to timeouts.

The workaround is ENABLE_EXPR_REWRITES=0.

It's not obvious what the answer is - should the FE be aware of the serialized size of an expression when deciding whether to constant fold it?

Issue Links

• is related to: IMPALA-7820 Limit JVM heap size in minicluster