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Posted to dev@phoenix.apache.org by "James Taylor (JIRA)" <ji...@apache.org> on 2016/01/24 04:09:39 UTC
[jira] [Updated] (PHOENIX-1648) Extra scan being issued while doing
SELECT COUNT(*) queries
[ https://issues.apache.org/jira/browse/PHOENIX-1648?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
James Taylor updated PHOENIX-1648:
----------------------------------
Fix Version/s: 4.8.0
> 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: 4.3.0
> Reporter: Samarth Jain
> Fix For: 4.8.0
>
>
> 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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