I thought I read in the documentation that 1000 was the max initial pages you could allocate, and after that, Derby allocates a page at a time. Is there some other setting for getting it to allocate more at a time?

 

Brian

 

From: Michael Segel [mailto:msegel@segel.com] On Behalf Of derby@segel.com
Sent: Friday, February 27, 2009 9:59 PM
To: 'Derby Discussion'
Subject: RE: inserts slowing down after 2.5m rows

 

Ok,

 

For testing, if you allocate 2000 pages, then if my thinking is ok, then you’ll fly along until you get until 2100 pages.

 

It sounds like you’re hitting a bit of a snag where after your initial allocation of pages, Derby is only allocating a smaller number of pages at a time.

 

I would hope that you could configure the number of pages to be allocated in blocks as the table grows.

 

 


From: publicayers@verizon.net [mailto:publicayers@verizon.net]
Sent: Friday, February 27, 2009 8:48 PM
To: Derby Discussion
Subject: Re: inserts slowing down after 2.5m rows

 

 I've increased the log size and the checkpoint interval, but it doesn't seem to help.

 

It looks like the inserts begin to dramatically slow down once the table reaches the initial allocation of pages. Things just fly along until it gets to about 1100 pages (I've allocated an initial 1000 pages, pages are 32k).

 

Any suggestions on how to keep the inserts moving quickly at this point?

 

Brian

 

On Fri, Feb 27, 2009 at  3:41 PM, publicayers@verizon.net wrote:

 

 The application is running on a client machine. I'm not sure how to tell if there's a different disk available that I could log to.

 

If checkpoint is causing this delay, how to a manage that? Can I turn checkpointing off? I already have durability set to test; I'm not concerned about recovering from a crashed db.

 

Brian

 

On Fri, Feb 27, 2009 at  9:34 AM, Peter Ondruška wrote:

 

> Could be checkpoint.. BTW to speed up bulk load you may want to use

large log files located separately from data disks.

 

2009/2/27, Brian Peterson < dianeayers@verizon.net >:

> I have a big table that gets a lot of inserts. Rows are inserted 10k at a

> time with a table function. At around 2.5 million rows, inserts slow down

> from 2-7s to around 15-20s. The table's dat file is around 800-900M.

>

>

>

> I have durability set to "test", table-level locks, a primary key index and

> another 2-column index on the table. Page size is at the max and page cache

> set to 4500 pages. The table gets compressed (inplace) every 500,000 rows.

> I'm using Derby 10.4 with JDK 1.6.0_07, running on Windows XP. I've ruled

> out anything from the rest of the application, including GC (memory usage

> follows a consistent pattern during the whole load). It is a local file

> system. The database has a fixed number of tables (so there's a fixed number

> of dat files in the database directory the whole time). The logs are getting

> cleaned up, so there's only a few dat files in the log directory as well.

>

>

>

> Any ideas what might be causing the big slowdown after so many loads?

>

>

>

> Brian

>

>

>

>