[MDEV-19480] Information schema queries return empty result set Created: 2019-05-15  Updated: 2023-04-27

Status: Confirmed
Project: MariaDB Server
Component/s: Information Schema
Affects Version/s: 10.3.14, 10.3.15, 10.3, 10.4
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Petri Luukkonen Assignee: Oleksandr Byelkin
Resolution: Unresolved Votes: 0
Labels: None
Environment:

Windows 10 64 bit


 Description   

For some reason following query returns empty result set in 10.3.14 and 10.3.15 version.

SELECT table_name,table_name, ordinal_position
FROM information_schema.table_constraints t
JOIN information_schema.key_column_usage k
USING(constraint_name,table_name)
WHERE t.constraint_type='PRIMARY KEY'
AND t.table_schema= 'demodb'
AND k.table_schema= 'demodb'

order by table_name,ordinal_position;

But following does work:

SELECT * FROM (SELECT t.table_name, k.column_name, ordinal_position
FROM information_schema.table_constraints t
JOIN information_schema.key_column_usage k
USING(constraint_name,table_name)
WHERE t.constraint_type='PRIMARY KEY'
AND t.table_schema= 'demodb'
AND k.table_schema= 'demodb') tmp

order by table_name,ordinal_position

 Comments   
Comment by Elena Stepanova [ 2019-05-16 ]

Thanks for the report and test case.

SELECT COUNT(*)
 
FROM information_schema.table_constraints t
 
JOIN information_schema.key_column_usage k
 
USING(constraint_name,table_name);
 
 
 
COUNT(*)
 
0
 
 
 
SELECT COUNT(*) FROM (SELECT t.*
 
FROM information_schema.table_constraints t
 
JOIN information_schema.key_column_usage k
 
USING(constraint_name,table_name)) tmp;
 
 
 
COUNT(*)
 
68

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