Question

BerkeleyDB: High Volume database hitting limits

Asked by: wevouch

I am using Berkeley DB to store real time ticks for market data. To give you an idea of the amount of data...
- I get roughly 15000 ticks/sec on an average
- by the end of the day the database file grows upto 50GB.

My system configuration is...
$ uname -a
Linux gritsbox.rsi.com 2.6.18-92.1.17.el5 #1 SMP Wed Oct 22 04:19:38 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux
- Quad core 1.6 Ghz
- 4GB RAM
- I have set the Berkeley db cache to 2GB and I am using the BTREE access method.

I started out using one database to store everything and it works well for 3/4th of the trading day. However, Db:puts increasingly start to take longer and towards the end of the day the delay is so high that I start loosing ticks. I figured that this could be because of BTREE trying to rebalance a heavy tree on every PUT (is this correct?)

I then decided to open 10000 (yeah!!!) databases in the environment, 1 for each symbol(ticker) that i am subscribed to. my idea behind this was that balancing a much smaller tree would be faster for Berkeley DB. However when i run the code, i get a "Db::open: Cannot allocate memory" error after opening just 300 something databases.

How do I make this work?

thanks

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2008-12-19 at 07:46:03ID23998629
Tags

Sleepycat

,

BerkeleyDB

,

C++ API

,

Berkeley DB

Topics

Databases Miscellaneous

,

Linux

,

Operating Systems Miscellaneous

,

Miscellaneous Hardware

Participating Experts
1
Points
500
Comments
5

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Tourism Marketing
    What are current trends of Marketing keeping in view the threat posed by internet to Travel Agents and Tour operators.Give the detail information and also the concerning web sites names?
  2. Best language(s) for accounting/trade database program?
    I am planning to write a good-sized accounting program that first keeps a database of all trades done by the company. It can then do a lot of report generation and can be very flexible with exporting and importing data with Excel. I feel the generic way to go about it is to...
  3. Power E*Trade - Market Trader
    I use Power E*Trade, Market Trader, and when I go to the site (www.etrade.com) you can choose the "Trading and portfolios" tab, then towards the top choose "Power E*Trade", you then have a list of options and you choose "use power e*trade market trade...
  4. Stock Market algorythm
    Does anyone know where I can find information about the kinds of algorythms used to determine current prices on the stock market? For example, the more people that want to buy a stock, the higher the price goes. But how does the algorythm work that determines how high the...
  5. Is it better to have higher GHz with a lower amount of cach…
    I'm looking at building a new computer with a multi-core Intel processor, but I am not sure if I would get better performance out of a 3.0 GHz processor with a 4mb cache or a 2.4GHz processor with an 8mb cache. They're are priced equally, and it is just a question of performa...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: GnsPosted on 2008-12-21 at 04:37:58ID: 23221699

I don't think your analysis of why the writes are quite right... I think it is _much_ simpler than that. Likely the initial seek just take a huge time to complete, so each write progressively slows... And for each tick, the write will be just  a tad slower....

Now, your second problem is that your wxcessive use of "DB files" simply lock a lot of memory. So that is a no-no.

I'd do one of a few different things:

- Allocate 3 database files/day. Programmatically switch what one to write to depending on the time ... so that you get three equal sized files over the workday.

- Switch to a real RDBMS. It would need some attention, so that a huge amount of writes don't make it keel over.... My "quant-users" used to do this for Reuters... They only saved about 50 ticks/second to our Oracle DB, but ... that was enough to put some hefty pressure on the server. The accumulated data, to be used for some time series or similar, wasn't used much (thankfully), since that would've been the real killer;-).

- Focus on usability. If the saved data cannot be used, don't save it;-):-). Massage it as best you can, then save the results.

Cheers
-- Glenn

 

by: wevouchPosted on 2008-12-22 at 15:53:22ID: 23230614

Thanks for your response Glenn.

- Allocating 3 files/day might work, the only problem is blocking all threads while the files are created and db pointers swapped. However, its worth a try and if nothing else works I would go for this.
- Real RDBMS: wouldnt that be slower? with the SQL layer and the data type checking that an RDBMS has to do (among other things). I actually tried this before I decided to go with BerkeleyDB and it was horribly slow. 25000 inserts/sec would be too much for RDBMS...rt?
- Yeah usability is paramount. A whole bunch of applications/servers are hungry for this realtime tick data. I am storing everything in the JSON format which is small and portable.

I have acheived significant performance improvement with the same 1 database by optimizing (and then reoptimizing) my code. However, its still not enough to handle occasional bursts of 40000 ticks/sec.

I think I have hit a limit on code optimizations. I am not going to upgrade to a quad core 3GHz... that might help... rt?

thanks
Nishant

 

by: GnsPosted on 2008-12-23 at 01:19:49ID: 23232232

Yes, 25000 inserts would put a horrible demand on the HW. You would need some rather big iron and some very clever tuning to accomodate that. But there could be solutions along that path as well, building things in memory and then bulk-loading (more or less telling your DB to quit checking things:-) should work with relatively normal HW. It all depends on the design, I suppose;). What you'd have to look at is limiting how _many_ sigular write operations you need do,,, (not doing autocommit, since that would commit too small chunks likely... have enough REDO/UNDO to "survive" the larger transactions you aim for etc DW stuff:-). There are ways to make RDBMSes fly, but compared to a slim Berkeley DB, in very specific situations... you are likely right.

If your measwurements indicate that you are CPU-starved, throwing iron on the problem might solve it, yes. Since all IO in *nix is more or less CPU-bound, more horsepower is never wrong (nor is more RAM:-).

I suppose you've looked on the ... simplistic things... already? Sar figures and such (to see that the system isn't trying to do housekeeping cron jobs, or similar, when it should be busy with saving ticks...)?

Cheers
-- Glenn

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...