[IMPALA-4260] Alter table add column drops all the column stats

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Impala 2.5.0
• Fix Version/s: Impala 2.8.0
• Component/s: Catalog
• Labels: statistics
• Target Version: Impala 2.8.0
• Assignee: Thomas Tauber-Marshall
• Reporter: Mostafa Mokhtar
• Created: 07/Oct/16 18:41
• Updated: 10/Sep/17 15:25
• Resolved: 07/Nov/16 22:32

Description

Adding a column after compute stats drops the per column stats, repro below

[vd0340.halxg.cloudera.com:21000] > compute stats single_node_insert.shipdates;
Query: compute stats single_node_insert.shipdates
+-----------------------------------------+
| summary                                 |
+-----------------------------------------+
| Updated 1 partition(s) and 4 column(s). |
+-----------------------------------------+
Fetched 1 row(s) in 0.72s
[vd0340.halxg.cloudera.com:21000] > show column stats single_node_insert.shipdates;
Query: show column stats single_node_insert.shipdates
+--------------+--------+------------------+--------+----------+-------------------+
| Column       | Type   | #Distinct Values | #Nulls | Max Size | Avg Size          |
+--------------+--------+------------------+--------+----------+-------------------+
| l_shipdate   | STRING | 2629             | -1     | 10       | 9.992899894714355 |
| l_orderkey   | BIGINT | 1                | -1     | 8        | 8                 |
| l_linenumber | BIGINT | 1                | -1     | 8        | 8                 |
| l_partkey    | BIGINT | 1                | -1     | 8        | 8                 |
+--------------+--------+------------------+--------+----------+-------------------+
Fetched 4 row(s) in 0.01s
[vd0340.halxg.cloudera.com:21000] > alter table shipdates add columns (l_custkey bigint);
Query: alter table shipdates add columns (l_custkey bigint)
[vd0340.halxg.cloudera.com:21000] > show column stats single_node_insert.shipdates;
Query: show column stats single_node_insert.shipdates
+--------------+--------+------------------+--------+----------+----------+
| Column       | Type   | #Distinct Values | #Nulls | Max Size | Avg Size |
+--------------+--------+------------------+--------+----------+----------+
| l_shipdate   | STRING | -1               | -1     | -1       | -1       |
| l_orderkey   | BIGINT | -1               | -1     | 8        | 8        |
| l_linenumber | BIGINT | -1               | -1     | 8        | 8        |
| l_partkey    | BIGINT | -1               | -1     | 8        | 8        |
| l_custkey    | BIGINT | -1               | -1     | 8        | 8        |
+--------------+--------+------------------+--------+----------+----------+

Issue Links

• is related to: IMPALA-4767 Table stats are removed after any ALTER TABLE in Impala