Jim Cross created DERBY-6939:
--------------------------------
Summary: Update statement poor performance with index using where
in (select
Key: DERBY-6939
URL: https://issues.apache.org/jira/browse/DERBY-6939
Project: Derby
Issue Type: Bug
Components: SQL
Affects Versions: 10.11.1.1
Reporter: Jim Cross
An update statement such as below doesn't appear to be using the index:
update mytable set col1 = 'myvalue' where indexed_col in (select index_col from
mytable where col1 like 'myv%' fetch first 100 rows only);
The table in this case has over a million rows. Running the sub-query:
select index_col from mytable where col1 like 'myv%' fetch first 100 rows only
Returns almost immediately with 100 rows but this update takes over two
minutes. Update does not seem to be using index because originally we try the
query without the index and performance after adding the index seemed to be the
same.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
