... and points beyond » data warehouse

Vertica for the Cloud

Jay Jakosky — Fri, 12 Dec 2008 06:36:01 +0000

While I have my head in the clouds, I should mention that Vertica has a cloud solution that they manage for you. Not new, but gives some perspective.

With competitive offerings in the $10-20k per terabyte, this is an attractive offer and a great way to try before you invest when you have that much data.

I hear Vertica is a screamer, but I can’t imagine getting sub-second results for 3 TB of data on 3 virtualized servers, for the same reasons I gave in my previous post.

Vertica for the Cloud Pricing

How One-Second Results Change Everything

Jay Jakosky — Mon, 22 Sep 2008 15:27:30 +0000

There’s a point where query response time is low enough that it changes the analysis game completely. This is the amount of time that a decision maker is willing to wait to get the next answer. Not the first answer, but the next one, and the next one. Eventually the frustration of waiting is worse than not knowing.

Salesperson: “What shipped yesterday? Ok, what’s the breakdown? Woah, what happened in that department? That markdown is too steep, who wrote that order? Which customer? What’s that rep’s extension?”

With one-second results, that analysis would have happened in the time it took you to read it. This is a competition against human nature. One-second results makes the difference between wishing you had the answer and getting it, multiplied over and over throughout the day.

The impact on a business is not from faster queries alone. Behavior changes when decision makers trust that the data is immediately at hand. The relationship to data changes when you can find the answer while you think about it and not lose your train of thought.

Because the query engine can respond to any query in one second, we can make every path of exploration available at the beginning. One application can take the place of many reports. Users can begin to query immediately and along any drill path. The benefit of one-second results is diminished if users have to first identify the report that has the data and filtering options they need.

Can OLAP deliver this? No. We must combine speed of execution with rapid application development, full transaction details, and eliminate predefined drill paths. OLAP/MOLAP/ROLAP/SCHMOLAP can’t take us into this new era. In-memory associative and column-store databases can.

With one-second results, you don’t build a query and then start the execution. Instead, the results update as soon as you pick the first filtering option, whether it’s the day, order number or country of origin. You get immediate feedback before you make your next selection. Also, the filter options can change based on the results. Maybe you remove options that are incompatible with the selections made so far. By shrinking the feedback loop with one-second results, the filtering options can show intelligent behavior to help guide users or add context to the results. This level of dynamism lets users roll back and forth through their ideas. They can cross-reference without losing a train of thought, or discover and follow tangents that are more important.

It’s not just one decision maker getting an answer quickly. Interactions and processes benefit. Workers get feedback in near-real-time. We can do tricks like running the same query once per second. Ridiculous? This isn’t paradise, I live in the land of low budgets and “getting it done”. Vendor and customer data is available right when they’re on the phone. Less “I’ll get back to you” and more “I have that info right in front of me.” I’ve also noticed that it’s harder to bullshit when anyone in the meeting can easily explore the data on their laptop and get the real answer.

In companies where I can deliver one-second results, I spend a lot of time reconditioning people to ask for anything they desire, because now I can put any information at their fingertips, no matter how many tables, how much detail and with little knowledge of how they want to look at the data.

For nearly all companies, the entire transactional database can be copied as-is into a one-second query engine. Add a BI tool on top, rename some fields and identify the table relationships. Time is spent developing the frontend to deliver the best reports and analysis. One person can build the entire solution. Since the transactional model is already validated, there is no data modeling, no formal architecture and little documentation. This might be frightening to enterprises but the benefits are huge for strapped IT budgets.

A one-second query engine needs an interactive frontend to take advantage of it. We also need simpler ETL tools. With the engine in place first, developers will connect the dots and the tools will be built to take advantage of the new abilities.

None of this is theoretical. I’ve been doing this for the past 7 years with an in-memory associative database, ETL tool and interactive frontend called QlikView. When information flows at the speed of thought, it changes decision-maker behavior and the business process. When we can prototype and deploy one-second query engines quickly, then ideas can be built and tested quickly. Most ideas won’t be new or unexpected, but they were impossible or impractical without one-second results.

InfoBright Open-Source Column-Store DBMS

Jay Jakosky — Tue, 16 Sep 2008 19:24:28 +0000

I wondered if InfoBright would do this. Before going open-source their website described the product as a kind of bulk-storage and not a data warehouse. A place to put data that you need to remain accessible but which you don’t need to query fast or frequently. That was the enterprise story. As an open-source project, I think they have a much more compelling value proposition. It’s the democratization of analysis. Try before you buy (the Enterprise Edition). Rapid prototype / rapid failure. Connects to any SQL tool, platform or language. As easy as working with MySQL.

My test data set is 37 million rows of point-of-sale transactions. Total data size as CSV is 7GB. My test system stinks. I need to make that clear so that my numbers are not seen as representative of what’s possible with InfoBright. After seeing the product in action, I’m sure that server hardware will do much better.

How fast to bulk load?

InfoBright loads are multi-threaded, but my test server is a single-processor desktop and the loads are still fast! With my single processor, about 1.8 million rows/minute (336 MB/min) are being inserted and the load rate slowed down about 10% over 37 million rows. Disk access was minimal as records were inserted. Overall, my little desktop moved an average of 30,000 rows/sec or 5.6 megabytes/sec. That’s 20GB/hour! My processor was fully loaded every second. With faster cores and multi-threading, the load should be much faster. When I get the chance to load Linux on a bigger box I’ll be eager to see how it performs.

How big on disk?

I have 7GB of data. Using MySQL’s default MyISAM storage engine with an 8-bit ASCII representation requires… 7GB. No surprise there. InfoBright took 591.2MB, as reported from my MySQL management console. That’s a 92% reduction in size or a 12:1 compression ratio.

The status data coming from the InfoBright engine includes the storage size of each column and total size of the table. If I could remove the lowest-level detail, InfoBright reports exactly how much space that would save. Helpful.

How much memory?

I don’t have much guidance because I don’t have enough data to stress the cache. My largest data set can fit comfortably inside the compressed cache. That means every company I’ve ever dealt with would be able to avoid disk reads and improve performance. Unfortunately, this does not put InfoBright’s performance on par with other in-memory databases. More on this later.

Here are some guidelines from InfoBright on the memory (in megabytes) that you should allocate given a certain amount of system memory. These figures have no relationship to the size of your data set. I also don’t know if 32 GB represents an upper limit for the InfoBright software. I suspect the point to this table is that the loader heap does not need to increase and that the compressed heap should increase the fastest but will not exceed the main heap.

# System Memory	Server Main Heap Size	Server Compressed Heap Size	Loader Main Heap
32GB	24000	4000	800
16GB	10000	1000	800
8GB	4000	500	800

ServerMainHeapSize – Size of the main memory heap in the server process, in MB
ServerCompressedHeapSize – Size of the compressed memory heap in the server, in MB.
LoaderMainHeapSize – Size of the memory heap in the loader process, in MB.

Performance?

Is it fast? Slow? My hardware is too restrictive to see what InfoBright can do. All signs are promising. What I can say is that the cache grew over time until MySQL was barely touching the disk. My processor is completely peaked, with 99.8% allocated to the MySQL process. According to this article published by MySQL yesterday, InfoBright queries are (for now) restricted to one CPU core. Performance is dependent on the size of my cache and the speed of each core, two things I have direct control over.

Even with my little desktop testbed, this much is clear: the QlikView in-memory database is much faster. On this dataset I’d see results in a split-second instead of 30, 60 or 120 seconds. You might think that comparing these two products isn’t fair, but if your goal is to deliver analysis in SMEs or enterprise departments, these two will definitely compete and complement one another.

Summary?

One of the advantages of column-stores for data warehousing is that simply replicating the original transactional schema can yield adequate performance. Also, there is no performance hit for bringing in the lowest level of granularity. With column-stores, you may not need to build snowflake schemas or do much transformation. Column-stores are therefore less effort to get started in smaller companies with resource-starved IT departments. This means a faster failure rate which is what interests me most: implement quickly, measure early impact and choose investment (InfoBright Enterprise), deferral or elimination.

There is one other free column-store database of significance, MonetDB. It’s an academic project and as such it lacks the toolset and polish that InfoBright inherited from MySQL. I was up and running faster with InfoBright than I was with MonetDB because the installers and administration utilities for InfoBright are already familiar. My Windows tools for MySQL connected right in without a problem. My front-ends with simplified MySQL connectors were oblivious to the InfoBright backend, which is absolutely how it should be.

InfoBright is not without its issues. Documentation is thin or non-existant. I spent hours and hours until I determined (and confirmed on the forums) that the InfoBright loader does not support all of the MySQL syntax for bulk loads. This would not have been such a problem if the error message had provided some warning about my syntax that was perfectly legal in standard MySQL.

All in all, I’m thrilled to have a no-cost column-store database available for prototyping, quick and dirty applications, and bulk data storage.

Low-Cost Data Analysis & Visualization: It’s Getting Better All The Time

Jay Jakosky — Mon, 08 Sep 2008 02:43:45 +0000

Over the weekend I have revisited Tableau, enjoyed some success with MonetDB, tried to turn MySQL into a hundred million row data warehouse, been underwhelmed with Firebird, installed Greenplum and spent many frustrated hours with Talend Open Studio, Pentaho Kettle and Jitterbit.

Of course, I could just buy QlikView, but what can be done for less $money? Unfortunately data warehouses and BI front-ends are not sexy problems in the opensource community. Graphs and charts get a little more attention, but you’ll need to write your own code to glue them to your application.

In summary, what can I say about our options?

First, write your own ETL. Why do opensource ETL tools like Talend and Kettle work so hard to rebuild Informatica? It reminds me of Linux in the 1990s when the community wanted to beat Windows and kept working to look like Windows and wondering when victory would arrive. Informatica, like OLAP and mainframes, is from an era when memory was scarce; languages were low-level, slow to compile & run, abstracted little and were not at all portable. On top of that, ODBC drivers were tightly controlled and costly.

But now we can pick from many great scripting languages. Today’s languages abstract the hard parts, are easy to read, can be edited while executing and talk to any system, database, web service or application. I think the next direction for ETL will be a simple (but extensible) transformation language using an ORM wrapper… Rails on ETL. Until that arrives, you can achieve everything you need with PHP, Perl, Ruby and others.

Best option for low-cost data warehouse?

Check out the totally free MonetDB. Unless Vertica or InfoBright reconsiders releasing a low/no cost option, MonetDB will likely mature to become a first-choice column-store database. It’s an academic project that has earned a sizeable development community and user base. The product is functional today for tens of millions of rows (maybe more). So far I have personally worked with a few million rows in MonetDB and I’d like to use it again. With a little focus on usability and packaging, it could be a contender.

Greenplum, freely available for development, won’t help. The architecture is designed around Massively Parallel Processing. As a single, standalone installation, it’s basically just PostgreSQL. You won’t see extra performance without a farm of servers.

To my surprise, MySQL itself is not too bad. The MyISAM tables are speedy and Alex Tomic wrote a post about using multiple queries against the Archive storage engine and how to steal an index with that engine. With basic MyISAM on a fast server, I’m running 10GB table scans in under a minute, but moderate aggregations take a few minutes. Architecturally, MySQL is limited. One query = one thread = one core. Running two simultaneous queries is an option, but MySQL still would not do the kind of transparent, optimized caching that you need for a warehouse. Throughput is limited to disk I/O speed. InfoBright has built a column-store storage engine for MySQL but it’s targeted for the enterprise only.

What about the front end?

For the money and quality and ease of integration, it’s hard to beat Tableau. $1800 bucks isn’t cheap, but for a small business that truly needs to analyze patterns, this will do the job and it makes very pretty charts. The most recent version has integrated support for mapping based on zip code, area code, state, country and others. The maps also incorporate Census and USGS data and are pulled live from an online source. They look great! Tableau has always had a smooth, easy-to-understand layout and a crisp look that makes each chart very attractive in a presentation. It also automatically guesses what chart you want based on the quality & number of aggregates and dimensions.

The drawback is that Tableau doesn’t have its own high-speed database or ETL tool. Tableau can’t shine until a low/no-cost read-optimized database is available. Until then, it does support the most common databases and data warehouses, both commercial and open-source. Except it can’t handle generic ODBC and I don’t know why.

There’s JasperSoft = CrystalReports + OLAP + Informatica + Web Dashboards. Each component is from a different opensource project, so they don’t all use the same platform or interface, and they can’t all read the same data sources. The democratization of BI is NOT going to come from enterprise tools made cheap; it will come from simple disruptive tools that add new ideas and polish with each release. Sorry, Jasper.

What would I use to build a reporting system for a smaller business?

Well, assuming we’re doing it to make more money, not to keep up appearances, the best choice is still to pay the money for QlikView. It reads ODBC, OLE DB, text files and Excel–everything a business needs. The ETL language is easy to understand for any businessperson that has put together an Access database or enjoys Excel formulas (blech!). The GUI front-end designer is powerful & straightforward. And the in-memory database behind QlikView is so incredibly fast that I routinely analyze 10 million of rows in a split-second. It’s a one-stop shop.

Tableau is a good option but you lose the database and ETL. Maybe you don’t have a large volume of data or maybe it’s all in one view in the database–Tableau could work for you.

At a lower cost? Well, it definitely comes down to tradeoffs in coder skill, money, development time and ease of use. Whereas in QlikView anyone can write the basic code to read a couple tables, all other solutions demand heavy lifting somehwere.

If I was doing it for free?

I’d start with PHP, and possibly Ruby. Read from a database, calculate, generate Google Charts, and maybe use one of the low/no-cost Flash-based charting libraries for interactive splash. In a future post I’d like to cover ORMs and Google Chart APIs and how it can help get these projects off and running quickly.

Got any ideas? I’m always on the lookout for a faster cheaper better way to create these solutions.

50 Cool Things You Can Do with Google Charts

How well do Netezza, Greenplum, Vertica and others handle 12-way joins?

Jay Jakosky — Mon, 26 Nov 2007 08:50:57 +0000

In my world, which is corporate software systems, I have a transactional database that is usually in second normal form and has very few aggregates. Building reports directly means joining at least 4 tables, often 8, and sometimes as many as 12. Unfortunately, the new crop of data warehouse vendors have made it very difficult to grasp how well they handle this. Some of these products handle your datamodel as-is, and some expect star/snowflake schemas, which adds a layer of design, coding, testing, validation and additional maintenance.

Netezza, Greenplum and Vertica all use off-the-shelf interconnects, meaning 1 gigabit ethernet in most cases. Transferring large amounts of data from a distributed system over ethernet can easily unravel any gains. In a simplistic design, an evenly distributed dataset would require that every node talks to every other node. With multiple joins, this would create a series of bottlenecks. It would also rely heavily on synchronization across the distributed system.

Vertica is a star/snowflake product. The Vertica distributed system replicates the dimension tables on each node and partitions the fact table. Vertica says that they have customers that use more transactional models, but what does that mean for overall performance? Greenplum’s website says: “Utilizes pipelining techniques and redistributes data among nodes for high performance execution of complex joins.” Encouraging, but what is considered “complex” and what will this do to my network in real-world conditions?

If you have any thoughts to share, please add them to the comments.

2007 Magic Quadrant for Data Warehouse

Jay Jakosky — Sun, 28 Oct 2007 18:58:25 +0000

Gartner released the updated quadrant for DW DBMS software and appliances. DATAllegro seems too far below Netezza in ability to execute. DATAllegro has large, proven installations. Their recent releases run on Dell blades with EMC storage instead of the customized FPGAs of Netezza. And how is Greenplum rated higher than DATAllego? (via DBMS2)

TeraData Performance at KiloData Prices

Jay Jakosky — Tue, 07 Aug 2007 20:46:21 +0000

What if you could turn on a massively parallel business intelligence database cluster with a few lines of code? What if you could leverage in-house and outsourced resources for computation and storage as needed? What if you could expand your analysis, data mining and text-search effort one node at a time, transparently, instantly?

There’s been a flurry of discussion around Hadoop and the Hbase project to bring Google’s BigTable feature to Hadoop.

Now Amazon wants to talk about how to use Hadoop with EC2 and S3, their computing and storage clusters.

Can I search large volumes of data on the cheap? Yes, but my algorithms must fit within the MapReduce framework.

Does someone have a MapReduce-enabled data query language? Well, there’s Pig from Yahoo. Sawzall from Google. Here is a discussion comparing those two from Greg Linden. Abacus from the Hadoop project. Apparently Microsoft has DryadLINQ.

We are on the exponential curve as it swoops upward dramatically. From the power and flexibility of opensource, anyone can use Google secret sauce on Amazon’s computers for 18 cents per gigabyte and 10 cents per computing hour.

More on Vertica

Jay Jakosky — Fri, 16 Feb 2007 20:34:00 +0000

The ideas in this paper will be incorporated into the Vertica database product. And unfortunately it won’t be open source. At least that’s what one company employee commented on Slashdot.

In the same way that RAID design options (e.g. 1, 5 and 10) can accommodate multiple drive failures, the Vertica system will distribute the same slice of the database to several servers. A grid of commodity hardware can act as a high-availability system and Vertica’s shared-nothing architecture enables this feature without complex design or execution.

We call a system that tolerates K failures K-safe. C-Store will be configurable to support a range of values of K.

Inserts and updates are performed on a separate data store and merged in batches. Deletes are marked with bitmasks. Rather than building a complex locking scheme for grid members, data in the read-only and write stores is stamped with a time “epoch”. Queries specify an epoch. It’s an elegant implementation that is very well suited to a data warehouse.

What’s Vertica?

Jay Jakosky — Fri, 16 Feb 2007 05:46:00 +0000

Started by a major contributor to the Ingres and Postgres projects, Vertica is implementing a read-optimized database that is an excellent fit for the data warehouse world. Given the founder’s support of open-source, I expect this company will follow the hybrid commercial/FOSS model of MySQL and others. Some core design features include highly compact storage, total ad-hoc read optimization, and using a shared-nothing grid design that is dead easy to implement with commodity (not High-Availability) hardware. Via Slashdot.

New database company raises funds, nabs ex-Oracle bigwigs – Network World