[PHOENIX-4287] Incorrect aggregate query results when stats are disable for parallelization

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.12.0
• Fix Version/s: 4.13.0
• Labels: localIndex statsCollection

Environment

HBase 1.3.1

• Assignee: Samarth Jain
• Reporter: Mujtaba Chohan
• Created: 13/Oct/17 21:07
• Updated: 26/Jul/18 01:12
• Resolved: 03/Nov/17 22:12

Description

With phoenix.use.stats.parallelization set to false, aggregate query returns incorrect results when stats are available.

With local index and stats disabled for parallelization:

explain select count(*) from TABLE_T;
+-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+
|                                                 PLAN                                                  | EST_BYTES_READ  | EST_ROWS_READ  |  EST_INFO |
+-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+
| CLIENT 0-CHUNK 332170 ROWS 625043899 BYTES PARALLEL 0-WAY RANGE SCAN OVER TABLE_T [1]  | 625043899       | 332170         | 150792825 |
|     SERVER FILTER BY FIRST KEY ONLY                                                                   | 625043899       | 332170         | 150792825 |
|     SERVER AGGREGATE INTO SINGLE ROW                                                                  | 625043899       | 332170         | 150792825 |
+-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+

select count(*) from TABLE_T;
+-----------+
| COUNT(1)  |
+-----------+
| 0         |
+-----------+

Using data table

explain select /*+NO_INDEX*/ count(*) from TABLE_T;
+--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+
|                                               PLAN                                               | EST_BYTES_READ  | EST_ROWS_READ  |  EST_INFO_TS   |
+--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+
| CLIENT 2-CHUNK 332151 ROWS 438492470 BYTES PARALLEL 1-WAY FULL SCAN OVER TABLE_T  | 438492470       | 332151         | 1507928257617  |
|     SERVER FILTER BY FIRST KEY ONLY                                                              | 438492470       | 332151         | 1507928257617  |
|     SERVER AGGREGATE INTO SINGLE ROW                                                             | 438492470       | 332151         | 1507928257617  |
+--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+

select /*+NO_INDEX*/ count(*) from TABLE_T;
+-----------+
| COUNT(1)  |
+-----------+
| 14        |
+-----------+

Without stats available, results are correct:

explain select /*+NO_INDEX*/ count(*) from TABLE_T;
+----------------------------------------------------------------------+-----------------+----------------+--------------+
|                                 PLAN                                 | EST_BYTES_READ  | EST_ROWS_READ  | EST_INFO_TS  |
+----------------------------------------------------------------------+-----------------+----------------+--------------+
| CLIENT 2-CHUNK PARALLEL 1-WAY FULL SCAN OVER TABLE_T  | null            | null           | null         |
|     SERVER FILTER BY FIRST KEY ONLY                                  | null            | null           | null         |
|     SERVER AGGREGATE INTO SINGLE ROW                                 | null            | null           | null         |
+----------------------------------------------------------------------+-----------------+----------------+--------------+
select /*+NO_INDEX*/ count(*) from TABLE_T;
+-----------+
| COUNT(1)  |
+-----------+
| 333327    |
+-----------+