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Posted to dev@phoenix.apache.org by "Mujtaba Chohan (JIRA)" <ji...@apache.org> on 2017/05/08 21:17:04 UTC
[jira] [Created] (PHOENIX-3836) Estimated row count is twice the
actual row count when stats are updated via major compaction
Mujtaba Chohan created PHOENIX-3836:
---------------------------------------
Summary: Estimated row count is twice the actual row count when stats are updated via major compaction
Key: PHOENIX-3836
URL: https://issues.apache.org/jira/browse/PHOENIX-3836
Project: Phoenix
Issue Type: Bug
Reporter: Mujtaba Chohan
Priority: Minor
Estimated row count for a 2M table is 3986498 after stats updated via major compaction vs 1993250 with {{update statistics}}.
{noformat}
Explain plan for count(*) on 2M row table after major compaction:
+--------------------------------------------------------------------------------------+
| PLAN |
+--------------------------------------------------------------------------------------+
| CLIENT 364-CHUNK 3986498 ROWS 3774892993 BYTES PARALLEL 1-WAY FULL SCAN OVER T |
| SERVER FILTER BY FIRST KEY ONLY |
| SERVER AGGREGATE INTO SINGLE ROW |
+--------------------------------------------------------------------------------------+
Explain plan for count(*) on 2M row table after update statistics:
+--------------------------------------------------------------------------------------+
| PLAN |
+--------------------------------------------------------------------------------------+
| CLIENT 364-CHUNK 1993250 ROWS 3774892993 BYTES PARALLEL 1-WAY FULL SCAN OVER T |
| SERVER FILTER BY FIRST KEY ONLY |
| SERVER AGGREGATE INTO SINGLE ROW |
+--------------------------------------------------------------------------------------+
{noformat}
Following schema was used with 2M rows and 10MB guidepost width:
{noformat}
CREATE TABLE IF NOT EXISTS T (PKA CHAR(15) NOT NULL, PKF CHAR(3) NOT NULL,
PKP CHAR(15) NOT NULL, CRD DATE NOT NULL, EHI CHAR(15) NOT NULL, STD_COL VARCHAR, INDEXED_COL INTEGER,
CONSTRAINT PK PRIMARY KEY ( PKA, PKF, PKP, CRD DESC, EHI))
VERSIONS=1,MULTI_TENANT=true,IMMUTABLE_ROWS=true
{noformat}
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