[MCOL-46] Unknown Error on Simple Semi Join query Created: 2016-05-06  Updated: 2016-10-12  Resolved: 2016-10-12

Status: Closed
Project: MariaDB ColumnStore
Component/s: MDB Plugin
Affects Version/s: None
Fix Version/s: 1.0.0, 1.0.4

Type: Bug Priority: Major
Reporter: David Hall (Inactive) Assignee: David Hall (Inactive)
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MCOL-280 Beta issues Closed
Sprint: 2016-20

 Description   

ref: working_tpch1_compareLogOnly/sub/g3_simple_semi_join.sql,

the very last query in the file.

MariaDB [tpch1]> select count(o_orderkey), sum(o_totalprice) from customer, orders where not exists (select n_nationkey from nation, region where n_regionkey = r_regionkey and r_name = 'ASIA') and o_custkey = c_custkey;

ERROR 1815 (HY000): Internal error: Unknown error

MariaDB [tpch1]>

 Comments   
Comment by Dipti Joshi (Inactive) [ 2016-05-31 ]

David.Hall dleeyh Does this error still occur ?

Comment by Daniel Lee (Inactive) [ 2016-05-31 ]

Build verified:

getsoftwareinfo Tue May 31 10:30:28 2016

Name : mariadb-columnstore-platform Relocations: (not relocatable)
Version : 1.0 Vendor: MariaDB Corporation Ab
Release : 0 Build Date: Fri 27 May 2016 04:07:53 PM EDT
Install Date: Mon 30 May 2016 11:32:15 AM EDT Build Host: srvbuilder

MariaDB [mytest]> select count(o_orderkey), sum(o_totalprice) from customer, orders where not exists (select n_nationkey from nation, region where n_regionkey = r_regionkey and r_name = 'ASIA') and o_custkey = c_custkey;
------------------------------------+

count(o_orderkey) sum(o_totalprice)

------------------------------------+

6000000 907317225789.84

------------------------------------+
1 row in set (1.74 sec)

Comment by David Hall (Inactive) [ 2016-10-11 ]

This has re-appeared.

Comment by David Hall (Inactive) [ 2016-10-12 ]

This problem occurs only on debug builds with the DEBUG_WALK_COND flag set.

The issue is that Item_cache::val_str() can and does sometimes call a full execution of the subquery. Who would have thought? Anyway debug_walk uses val_str() to print out useful information about the item. In this case, it causes an execution of the subquery when we're not set up for it, confusing everything.

Fixed by not calling val_str() for Item_cache objects. This debug info just won't get printed.

Comment by David Hall (Inactive) [ 2016-10-12 ]

Since this bug only affects debug builds, it's not useful to send to test

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