[CALCITE-3472] SESSION_END returns same value as SESSION_START

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Fix Version/s: 1.22.0
• Component/s: stream
• Assignee: Unassigned
• Reporter: Pablo Estrada
• Created: 04/Nov/19 04:15
• Updated: 28/May/21 10:09
• Resolved: 04/Nov/19 20:03

Description

We've found that the session_end function seems to be returning the same values as session_start. Furthermore, it seems that they may have the same implementation, though I'm not fully familiar with the code:

 

https://github.com/apache/calcite/blob/d7946a94adfd2e788f5d324910944dd65dab11ee/core/src/main/java/org/apache/calcite/sql2rel/AuxiliaryConverter.java#L50-L68

 

An example with Beam SQL:

 

0: BeamSQL> SELECT
SESSION_START(scores_stream.event_time, INTERVAL '1' SECOND),
SESSION_END(scores_stream.event_time, INTERVAL '1' SECOND),
scores_stream.team,
SUM(scores_stream.score),
COUNT
FROM
scores_stream
GROUP BY scores_stream.team,
SESSION(scores_stream.event_time, INTERVAL '1' SECOND) LIMIT 3;SELECT
. . . . . > SESSION_START(scores_stream.event_time, INTERVAL '1' SECOND),
. . . . . > SESSION_END(scores_stream.event_time, INTERVAL '1' SECOND),
. . . . . > scores_stream.team,
. . . . . > SUM(scores_stream.score),
. . . . . > COUNT
. . . . . > FROM
. . . . . > scores_stream
. . . . . > GROUP BY scores_stream.team,
. . . . . >
T 3; SESSION(scores_stream.event_time, INTERVAL '1' SECOND) LIMI
-----------------------------------------------

EXPR$0

EXPR$1

team

EXPR$3

EXPR$4

-----------------------------------------------

2019-11-04 04:11:38	2019-11-04 04:11:38	blue	420	7
2019-11-04 04:11:38	2019-11-04 04:11:38	red	960	18
2019-11-04 04:11:42	2019-11-04 04:11:42	blue	452	11

-----------------------------------------------
3 rows selected (9.197 seconds)
0: BeamSQL>

Issue Links

• duplicates: CALCITE-2645 SESSION_END() is transformed to RexInputRef, which is always equal to SESSION_START()