We've seen similar behavior, but not with deleting a record. We seem massive slowdowns occasionally after importing some data, but restarting the service seems to resolve it. It's happening frequently enough though that we're either needing to fix it or move to something else. :-(

Thanks,

Joseph Brower

On 05/10/2012 04:44 AM, suncpp wrote:

Hi,

I have tested the same DB on Windows 7 and Ubuntu 10.04. The performance after deletion of 1 record slows down on both OS. Tested version is Apr2012.

Here is an example of my table: CREATE TABLE t ( s_id int DEFAULT NULL, time int DEFAULT NULL, a_id int DEFAULT NULL, x bigint DEFAULT NULL, y bigint DEFAULT NULL, z bigint DEFAULT NULL );

And here is my query: SELECT t.a_id, SUM(t.x), SUM(t.y), SUM(t.z) FROM ( SELECT MAX(time) AS max_time, a_id FROM t WHERE time<= 1345282581 AND a_id IN (1, 5, 9, 12) AND s_id = 3 GROUP BY a_id ) AS tmp INNER JOIN t ON 3 = t.s_id AND tmp.max_time = t.time AND tmp.a_id = t.a_id GROUP BY t.attr_id ;

Notes: number of different a_id's is about 100, number of different s_id's is about 50,000.

If table t consists of 15,000,000 records the execution of query above takes about 50ms. Right after the deletion of 1 record the execution takes about 330ms (I run query 5 times and took the average value). So the difference is considerable. What can I do to get back the former performance?

Any ideas? Thanks for any advance.

suncpp wrote:

...

Hi everyone,

I had added about 30,000,000 records in one MonetDB table. The performance of executing SELECT-queries was really great. But after the deletion of only 1 record from the table, the performance had slowed down considerably.

I have seen the topics here with alike problems but I have not found the solution. Could anyone help me to understand what the problem is?