[IMPALA-3988] Only use first 96 bits of query ID

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.7.0
• Fix Version/s: Impala 2.8.0
• Component/s: Backend
• Labels: ramp-up
• Target Version: Impala 2.8.0
• Assignee: Marcel Kinard
• Reporter: Henry Robinson
• Created: 17/Aug/16 18:16
• Updated: 14/Sep/16 17:39
• Resolved: 14/Sep/16 17:39

Description

Impala generates 128-bit query ids for every query. Individual fragments also get IDs, which are the query_id + (fragment number). To make this clearer to read, let's reserve the bottom 32 bits of the query id space for fragment numbers, and only use the top 96 bits for query ids. That is, in the hex representation the bottom 8 characters will always be 0 for query ids.