[IMPALA-4168] Adopt Oracle-style hint placement for INSERT statements

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.2, Impala 2.3.0, Impala 2.5.0, Impala 2.4.0, Impala 2.6.0, Impala 2.7.0
• Fix Version/s: Impala 2.12.0
• Component/s: Frontend
• Labels: incompatibility ramp-up
• Epic Link: Improve the reliability and effectiveness of ETL
• Target Version: Product Backlog
• Assignee: Jin Chul Kim
• Reporter: Alexander Behm
• Created: 20/Sep/16 00:57
• Updated: 04/Apr/18 19:04
• Resolved: 10/Jan/18 18:49

Description

For consistency with Oracle we should consider accepting hints in the same places in SQL statements. For example, our current INSERT statements accepts hints right before the SELECT portion:

INSERT INTO t PARTITIONED(year,month) /*+ hints */ SELECT * FROM src;

The proposal is to accept hints immediately after INSERT like Oracle does:

INSERT /*+ hints */ INTO t PARTITIONED(year,month) SELECT * FROM src;

Ideally, we would not accept hints in multiple places to avoid confusion and to reduce the code and testing burden. Ceasing to recognize the old hint placement is a backwards incompatible change.

Issue Links

• is related to: IMPALA-4191 standardize query hint syntax