[jira] [Created] (PHOENIX-1648) Extra scan being issued while doing SELECT COUNT(*) queries

["Samarth Jain (JIRA)" <ji...@apache.org>]

Samarth Jain created PHOENIX-1648:
-------------------------------------

             Summary: Extra scan being issued while doing SELECT COUNT(*) queries
                 Key: PHOENIX-1648
                 URL: https://issues.apache.org/jira/browse/PHOENIX-1648
             Project: Phoenix
          Issue Type: Bug
    Affects Versions: 5.0.0, 4.3
            Reporter: Samarth Jain


On turning tracing on and executing SELECT COUNT(*) queries, I am seeing an extra scan being executed every time. 

CREATE TABLE MY_TABLE (ID INTEGER NOT NULL PRIMARY KEY, VALUE INTEGER) SALT_BUCKETS = 16

SELECT COUNT(*) FROM MY_TABLE

The trace table has:

Creating basic query for [CLIENT 16-CHUNK PARALLEL 16-WAY FULL SCAN OVER MY_TABLE,     SERVER FILTER BY FIRST KEY ONLY,     SERVER AGGREGATE INTO SINGLE ROW]
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Parallel scanner for table: MY_TABLE
Creating basic query for [CLIENT 1-CHUNK PARALLEL 1-WAY RANGE SCAN OVER SYSTEM.CATALOG [null,null,'MY_TABLE',not null],    SERVER FILTER BY COLUMN_FAMILY IS NULL]
Parallel scanner for table: SYSTEM.CATALOG


While the 16 scanners being created for MY_TABLE is expected, the extra scanner for SYSTEM.CATALOG isn't. This is happening consistently, so this likely isn't happening because of cache expiration. 




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