[CALCITE-2271] Join of two views with window aggregates produces incorrect results or NPE

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.16.0
• Fix Version/s: 1.18.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Alexey Makhmutov
• Created: 20/Apr/18 21:32
• Updated: 23/Dec/18 00:12
• Resolved: 28/Aug/18 07:08

Description

This is a continuation of CALCITE-2081. The problem wasn't really solved in scope of that ticket:

1. It produces incorrect results, even in the unit-test which was included into the fix (function last_value(empid) shouldn't produce NULL in such query).
2. NPE is still present for more complex queries with joined window functions (e.g. if window functions with the same name are used in both part of the join).

Here is the example of the query, which produces NPE in 1.16.0:

select 
 t1.l, t1.key, t2.key
from 
 (
  select 
   dense_rank() over (order by key) l, 
   key 
  from 
   unnest(map[1,1,2,2]) k
 ) t1 
 join 
 (
  select 
   dense_rank() over(order by key) l, 
   key 
  from 
   unnest(map[2,2]) k
 ) t2 on (t1.l = t2.l and t1.key + 1 = t2.key)

The problem is still the same - windows produces several declarations with non-unique names, which are then incorrectly merged in BlockBuilder.append method (declaration name substitution conflicts with optimization logic).

Two variables were fixed in scope of CALCITE-2081 - 'prevStart' and 'prevEnd', but other variables are still non-unique: result and state variables (aXwY and aXsYwZ which cause NPE during initialization) and 'list' variable (causing wrong results as both aggregates are storing results into the same variable).

Issue Links

• is duplicated by: CALCITE-2511 Possible bug in parsing implementation of rown_num select