Data warehousing
Analysis of issues in data warehousing, with extensive coverage of database management systems and data warehouse appliances that are optimized to query large volumes of data. Related subjects include:
User data vs. raw disk space as a marketing metric
I tried to post a comment on Daniel Abadi’s blog, but doing so seems to require some sort of registration process, so I’m posting here instead.
In a comment to his post on node scalability, Daniel Abadi argued that disk space is a better metric to use in marketing than (presumably compressed) user data. Well, I imagine he didn’t quite mean to say that, but that’s actually what he wound up saying, starting from the accurate observation that compression ratios vary wildly from one data set to another, even more than they vary from product to product on the same data.
Nonetheless, I favor user data as a metric because:
- That’s what users care about.
- That’s how a number of analytic DBMS vendors, including Vertica, actually price.
| Categories: Data warehousing, Parallelization, Pricing | 3 Comments |
The TPC-H schema
Would anybody recommend in real life running the TPC-H schema for that data? (I.e., fully normalized, no materialized views.) If so — why????
| Categories: Benchmarks and POCs, Data warehousing | 8 Comments |
Notes on columnar/TPC-H compression
I was chatting with Omer Trajman of Vertica, and he said that a 70% compression figure for ParAccel’s recent TPC-H filing sounded about right.* When I noted that seemed kind of low, Omer pointed out that TPC-H data is pseudo-random, while real-life data has much more correlation among the values in different columns. E.g., in retail, a customer is likely to consistently shop at the same stores and to put similar items into his shopping basket).
*Omer was involved in Vertica’s TPC-H-data-based load speed benchmark, and is Vertica’s representative to the TPC.
But why does this matter? After all, Vertica compresses one column at a time (unlike, say, Clearpace). Well, the reason is that Vertica — like other column stores — wants to store different columns in the same row order, for obvious benefits in both reading and writing. So, for example, if all the rows that include Gotham City are grouped sequentially, then all the rows mentioning Bruce Wayne are likely to be near each other as well, while none of the rows that mention Clark Kent will be mixed in.
And when a set of consecutive entries has low cardinality, it’s easier to get high levels of compression.
| Categories: Benchmarks and POCs, Columnar database management, Data warehousing, Database compression, Vertica Systems | Leave a Comment |
NoSQL?
Eric Lai emailed today to ask what I thought about the NoSQL folks, and especially whether I thought their ideas were useful for enterprises in general, as opposed to just Web 2.0 companies. That was the first I heard of NoSQL, which seems to be a community discussing SQL alternatives popular among the cloud/big-web-company set, such as BigTable, Hadoop, Cassandra and so on. My short answers are:
- In most cases, no.
- Most of these technologies are designed for simple, high-volume OLTP (OnLine Transaction Processing.) Most large enterprises have an established way of doing OLTP, probably via relational database management systems. Why change?
- MapReduce is an exception, in that it’s designed for analytics. MapReduce may be useful for enterprises. But where it is, it probably should be integrated into an analytic DBMS.
- There’s one big countervailing factor to all these generalities — schema flexibility.
As for the longer form, let me start by noting that there are two main kinds of reason for not liking SQL.
Correction to a recent quote
I’m quoted in a recent article around Aster’s appliance announcement as saying data warehouse appliances are more suitable for small workgroups of analysts crunching small amounts of data than they are for other uses.
But that’s not what I think at all.
I do think the ease-of-administration pitch for appliances makes them particularly well suited for users who want to scrape by without doing much database adminstration. This is especially appealing to departments or smaller enterprises. And the first/best scenario that comes to mind is indeed a small team of analysts, with good SQL skills but lightweight DBA experience, although Netezza has proved that many other kinds of users can find appliances appealing as well.
But that small team of analysts may maintain the largest database in the firm.
And by the way — notwithstanding the MySpace counterexample, most of Aster’s initial customers had <10 terabyte databases, and I think indeed <5 terabyte. The “frontline” pitch succeeded for Aster before (MySpace again aside) any better-big-data-crunching story did.
| Categories: Analytic technologies, Aster Data, Data warehouse appliances, Data warehousing, Theory and architecture | Leave a Comment |
Xtreme Data readies a different kind of FPGA-based data warehouse appliance
Xtreme Data called me to talk about its plans in the data warehouse appliance business, almost all details of which are currently embargoed. Still, a few points may be worth noting ahead of more precise information, namely:
- Xtreme Data’s basic idea is to take a custom board and build a data warehouse appliance around it.
- An Xtreme Data board looks a lot like a conventional two-socket board, but has only one four-core CPU. In addition, it sports some FPGAs (Field-Programmable Gate Arrays).
- In the Xtreme Data appliance, the FPGAs will be used for core SQL processing, after the data is ingested via conventional I/O. This is different from Netezza’s approach to FPGA-based data warehouse appliances, in which the FPGA sits in the place of a disk controller and touches the data first, before passing it off to a more or less conventional CPU.
- While preparing entry into the data warehouse appliance business, Xtreme Data has sold its board to 150 other outfits, many quite impressive. Buyers seem to be FPGA users who previously had to craft their own custom boards. According to Xtreme Data, major uses by these customers include:
- Military/intelligence/digital signal processing.
- Military/intelligence/cybersecurity (a newish area for Xtreme Data)
- Bioinformatics/high-throughput gene sequencing (a “handful” of customers)
- Medical imaging
- More or less pure university research of various sorts (around 50 customers)
- … but not database management.
- Xtreme Data’s website has a non-obvious URL.
So far as I can tell, Xtreme Data’s 1.0 product will — like most other 1.0 analytic database management products — be focused on price/performance, without little or no positive differentiation in the way of features.
| Categories: Data warehouse appliances, Data warehousing, Netezza, Theory and architecture | 6 Comments |
Aster Data enters the appliance game
Aster Data is rolling out a line of nCluster appliances today. Highlights include:
- Configurations ranging from 9 6.25 terabytes to 1 petabyte of user data. (Edit: Here’s the up-to-date data sheet.)
- A $50K “Express Edition” price for <1 terabyte of user data. Unfortunately, that’s the only stated price.
- The option of bundled MicroStrategy.
- “MapReduce” in the name, which suggests something about the positioning — i.e., enterprise decision support, rather than Aster’s usual web/”frontline” emphasis. (Edit: That also fits with Aster’s recent MapReduce-for-.NET announcement.) (Edit: Actual name is Aster MapReduce Data Warehouse Appliance.)
- Claims that because Aster runs effectively on cheaper, more truly “commodity” hardware than competitors, you get more hardware bang for the buck if you buy from Aster.
I don’t have a lot more to add right now, mainly because I wrote at some length about Aster’s non-appliance-specific, non-MapReduce technology and positioning a couple of weeks ago.
| Categories: Analytic technologies, Aster Data, Business intelligence, Data warehouse appliances, Data warehousing, Database compression, MapReduce, Pricing | 16 Comments |
My current customer list among the analytic DBMS specialists
(This is an updated version of an August, 2008 post.)
One of my favorite pages on the Monash Research website is the list of many current and a few notable past customers. (Another favorite page is the one for testimonials.) For a variety of reasons, I won’t undertake to be more precise about my current customer list than that. But I don’t think it would hurt anything to list the analytic/data warehouse DBMS/appliance specialists in the group. They are:
- Aster Data
- Greenplum
- Infobright
- Kickfire
- Kognitio
- Microsoft
- Netezza (my biggest client this year, probably, because of all the Enzee Universe appearances)
- Sybase
- Teradata
- Vertica
- Attivio, which may or may not be construed as being in the analytic DBMS business
- Clearpace, ditto
All of those are Monash Advantage members.
If you care about all this, you may also be interested in the rest of my standards and disclosures.
| Categories: About this blog, Aster Data, Data warehousing, Greenplum, Infobright, Kickfire, Microsoft and SQL*Server, Netezza, Sybase, Teradata, Vertica Systems | 2 Comments |
ParAccel pricing
As I noted in connection with ParAccel’s recent TPC-H filing, I think the whole exercise is basically an expensive joke. But one slightly useful spin-off is that ParAccel disclosed pricing. Specifically, ParAccel’s stated price in the disclosure document is:
- $100,000/TB license fee (user data). That’s like Vertica, although I don’t know whether ParAccel emulates Vertica’s policy of making test and development licenses free.
- 57% quantity discount at 30 terabytes. That’s not surprising.
- 1% annual maintenance fee (applied to the discounted price). That’s astounding.
Last year ParAccel quoted prices of $100,000/TB or $50,000/server. The latter figure would seem to have led to lower numbers on the benchmark configuration, so perhaps it’s no longer an option on ParAccel’s price list.
| Categories: Benchmarks and POCs, Data warehousing, ParAccel, Pricing | 2 Comments |
The TPC-H benchmark is a blight upon the industry
ParAccel has released a 30,000-gigabtye TPC-H benchmark, and no less a sage than Merv Adrian paid attention. Now, the TPCs may have had some use in the 1990s. Indeed, Merv was my analyst relations contact for a visit to my clients at Sybase around the time — 1996 or so — I was advising Sybase on how to market against its poor benchmark results. But TPCs are worthless today.
It’s not just that TPCs are highly tuned (ParAccel’s claim of “load-and-go” is laughable Edit: Looking at Appendix A of the full disclosure report, maybe it’s more justified than I thought.). It’s also not just that different analytic database management products perform very differently on different workloads, making the TPC-H not much of an indicator of anything real-life. The biggest problem is: Most TPC benchmarks are run on absurdly unrealistic hardware configurations.
For example, if you look at some details, the ParAccel 30-terabyte benchmark ran on 43 nodes, each with 64 gigabytes of RAM and 24 terabytes of disk. That’s 961,124.9 gigabytes of disk, officially, for a 32:1 disk/data ratio. By way of contrast, real-life analytic DBMS with good compression often have disk/data ratios of well under 1:1.
Meanwhile, the RAM:data ratio is around 1:11 It’s clear that ParAccel’s early TPC-H benchmarks ran entirely in RAM; indeed, ParAccel even admits that. And so I conjecture that ParAccel’s latest TPC-H benchmark ran (almost) entirely in RAM as well. Once again, this would illustrate that the TPC-H is irrelevant to judging an analytic DBMS’ real world performance.
More generally — I would not advise anybody to consider ParAccel’s product, for any use, except after a proof-of-concept in which ParAccel was not given the time and opportunity to perform extensive off-site tuning. I tend to feel that way about all analytic DBMS, but it’s a particular concern in the case of ParAccel.
| Categories: Analytic technologies, Benchmarks and POCs, Buying processes, Columnar database management, Data warehousing, Database compression, ParAccel | 85 Comments |
Aster Data on parallelism
Aster Data’s core claim boils down to “We do parallelism better.” Aster has shied away from saying that for marketing purposes, for fear of the response “Yeah, right, everybody says that.” But when I talked with Mayank Bawa, Steve Wooledge, et al. yesterday, I focused discussions on just that point. Based on that chat and others before, here are some highlights (as I understand them) of what Aster claims, believes, or believes to be differentiated about its nCluster technology:
| Categories: Analytic technologies, Aster Data, Data warehousing, MapReduce, Parallelization, Theory and architecture | 3 Comments |
Dataupia’s troubles are now confirmed
Todd Fin pointed me yesterday to an article by Wade Roush that confirmed in detail layoffs and other troubles at Dataupia. The article quotes Dataupia marketing VP Samantha Stone as saying Dataupia is down to 23 employees, and that some of the layoffs were in engineering. This is consistent with what I’d been hearing for a while, namely that other analytic DBMS vendors were seeing a flood of Dataupia resumes, especially technical ones.
The article goes on to discuss difficulties Dataupia has had in raising another round of financing. During Dataupia’s very long CEO search — which I kept hearing about from people who’d been approached for the job — it was obvious money wouldn’t come in until a CEO was found. But it seems that even with a new CEO, existing investors are reluctant to re-up without a new investor as well, and that new investment is slow in happening.
On the plus side, the article quotes Samantha as saying founder Foster Hinshaw is recovering well from his heart surgery.
| Categories: Data warehouse appliances, Data warehousing, Dataupia, Emulation, transparency, portability | 2 Comments |
Netezza Q1 earning call transcript
I finally read the Netezza Q1 earnings call transcript, put out by Seeking Alpha. Highlights included:
- Netezza got 14 new-name accounts and 21 follow-on deals. Average sale in both groups was right around $1 million.
- The economy is tough, deals are slipping, and nobody knows for sure what will happen.
- Netezza’s main head-to-head competitors are Oracle and Teradata. Netezza claims good but not perfect win rates against each, but concedes that those vendors (especially Oracle) of course get other deals Netezza never sees.
- Netezza characterizes Teradata as offering its multiple product lines, trying to upsell many customers from cheaper to more expensive product lines, and being selectively aggressive about pricing. None of this is surprising to me.
- 80% of Netezza’s Q1 revenue, and perhaps even a higher fraction of new-name accounts, was in four vertical markets: “Digital media,” telecom, government, and financial services.
- Some time over the next few months, Netezza will give at least some more clarity about future products.
One tip for the Netezza folks, by the way, from this former stock analyst — you should never use the word “certainly” about a deal you haven’t closed yet. “Almost surely” could be OK, but “certainly” — well, it certainly was not the thing to say.
Aster Data sticks by its SQL/MapReduce guns
Aster Data continues to think that MapReduce, integrated with SQL, is an important technology. For example:
- Aster announced today that it’s providing .NET support for SQL/MapReduce. Perhaps not coincidentally, Aster’s biggest customer is MySpace, which is apparently a big Microsoft shop. (And MySpace parent Fox Interactive Media is a SQL/MapReduce fan, albeit running on Greenplum.)
- Aster generally puts more emphasis on MapReduce than SQL/MapReduce rival Greenplum. That’s a non-trivial comparison, because Greenplum is making progress in SQL/MapReduce itself.
- When talking with Aster folks, I can’t get them to shut up hear a lot about SQL/MapReduce.
I was a big fan of SQL/MapReduce when it was first announced last August. Notwithstanding persuasive examples favoring pure DBMS or pure MapReduce over DBMS/MapReduce integration, I continue to think the SQL/MapReduce idea has great potential. But I do wish more successful production examples would become visible …
| Categories: Analytic technologies, Aster Data, Data warehousing, Fox and MySpace, Greenplum, MapReduce, Parallelization | 3 Comments |
Per-terabyte pricing
Software-only DBMS vendors sometimes price per terabyte of user data. Vertica’s list price is $100K/TB. Greenplum’s list price is $70K/TB. In practice, both offer substantial discounts, especially at higher volumes. In both cases, this means raw data, uncompressed, without counting indexes or temp space.
Client experience teaches me that this definition is easy to forget, so let me reemphasize the key point:
Per-terabyte pricing is based on a calculated figure. Per-terabyte pricing is not based on the current disk space used by your database when managed by the DBMS you are replacing.
There’s at least one important difference in how Vertica and Greenplum calculate database size. No matter how many times you copy the data, Vertica only charges you for it once.* But if you spin out data marts and recopy data into it — as Greenplum rightly encourages you to do — Greenplum wants to be paid for each copy. Similarly, Vertica charges only for deployment, and not for test or development; I didn’t remember to ask what Greenplum’s policies are in those regards. (Edit: Greenplum says in a comment below that it doesn’t charge for test or development data either.)
*That policy is a great fit with Vertica’s performance recommendation that you should store columns in different sort orders, perhaps an average of two copies per column.
| Categories: Columnar database management, Data warehousing, Greenplum, Pricing, Vertica Systems | 4 Comments |
Greenplum blogs about some customers
I’ve written some about Greenplum’s customers at eBay and Fox Interactive Media. But as I recently grumped, I’m not in the mood right now to write much about other Greenplum customers. Fortunately, Greenplum has filled the gap itself. Marketing chief Paul Salazar just blogged about a number of other big Greenplum customers. And last month Paul blogged in considerable detail about what he characterizes as an enterprise data warehouse (EDW) conversion — Oracle replacement — at a large pharmaceutical company.
| Categories: Application areas, Data warehousing, Greenplum, Oracle | Leave a Comment |
The future of data marts
Greenplum is announcing today a long-term vision, under the name Enterprise Data Cloud (EDC). Key observations around the concept — mixing mine and Greenplum’s together — include:
- Data marts aren’t just for performance (or price/performance). They also exist to give individual analysts or small teams control of their analytic destiny.
- Thus, it would be really cool if business users could have their own analytic “sandboxes” — virtual or physical analytic databases that they can manipulate without breaking anything else.
- In any case, business users want to analyze data when they want to analyze it. It is often unwise to ask business users to postpone analysis until after an enterprise data model can be extended to fully incorporate the new data they want to look at.
- Whether or not you agree with that, it’s an empirical fact that enterprises have many legacy data marts (or even, especially due to M&A, multiple legacy data warehouses). Similarly, it’s an empirical fact that many business users have the clout to order up new data marts as well.
- Consolidating data marts onto one common technological platform has important benefits.
In essence, Greenplum is pitching the story:
- Thesis: Enterprise Data Warehouses (EDWs)
- Antithesis: Data Warehouse Appliances
- Synthesis: Greenplum’s Enterprise Data Cloud vision
When put that starkly, it’s overstated, not least because
Specialized Analytic DBMS != Data Warehouse Appliance
But basically it makes sense, for two main reasons:
- Analysis is performed on all sorts of novel data, from sources far beyond an enterprise’s core transactions. This data neither has to fit nor particularly benefits from being tightly fitted into the core enterprise data model. Requiring it to do so is just an unnecessary and painful bureaucratic delay.
- On the other hand, consolidation can be a good idea even when systems don’t particularly interoperate. Data marts, which commonly do in part interoperate with central data stores, have all the more reason to be consolidated onto a central technology platform/stack.
More on Fox Interactive Media’s use of Greenplum
Greenplum’s most important reference is probably its energetic advocate Fox Interactive Media, even ahead of much larger user Greenplum user eBay, and notwithstanding Aster Data’s large presence in Fox subsidiary MySpace. I just ran across a “review” of Greenplum by FIM’s Brian Dolan, neatly summarizing his views about Greenplum’s strengths, weaknesses, and uses inside Fox. Highlights include: Read more
| Categories: Data warehousing, Fox and MySpace, Greenplum, Web analytics | 1 Comment |
Merv Adrian on SAND Technology
Merv Adrian blogged about SAND Technology, casting significant doubt on SAND’s business prospects. At this point, I can’t say I disagree. On the other hand, SAND does have public, audited financial statements showing it generating more revenue than a lot of other analytic DBMS or archiving vendors probably make. Columnar DBMS vendors doing better than SAND are Sybase, Vertica, maybe Infobright — and who else?
| Categories: Archiving and information preservation, Columnar database management, Data warehousing, SAND Technology | 1 Comment |
Daniel Abadi on Kickfire and related subjects
Daniel Abadi has a new blog, whose first post centers around Kickfire. The money quote is (emphasis mine):
In order for me to get excited about Kickfire, I have to ignore Mike Stonebraker’s voice in my head telling me that DBMS hardware companies have been launched many times in the past are ALWAYS fail (the main reasoning is that Moore’s law allows for commodity hardware to catch up in performance, eventually making the proprietary hardware overpriced and irrelevant). But given that Moore’s law is transforming into increased parallelism rather than increased raw speed, maybe hardware DBMS companies can succeed now where they have failed in the past
Good point.
More generally, Abadi speculates about the market for MySQL-compatible data warehousing. My responses include:
- OF COURSE there are many MySQL users who need to move to a serious analytic DBMS.
- What’s less clear is whether there’s any big advantage to those users in remaining MySQL-compatible when they do move. I’m not sure what MySQL-specific syntax or optimizations they’d have that would be difficult to port to a non-MySQL system.
- It’s nice to see Abadi speaking well of Infobright and its technology.
- To say that Infobright went open source because it was “desperate” is overstated. That said, I don’t think Infobright was on track to prosper without going open source.
- While open source and MySQL go together, an appliance like Kickfire loses many (not all) of the benefits of open source.
- Calpont has indeed never disclosed a customer win. Any year now … (Just kidding, Vogel!)
- In general, seeing Abadi be so favorable toward Vertica competitors adds credibiity to the recent Hadoop vs. DBMS paper.
Anyhow, as previously noted, I’m a big Daniel Abadi fan. I look forward to seeing what else he posts in his blog, and am optimistic he’ll live up to or exceed its stated goals.
| Categories: Calpont, Columnar database management, DBMS product categories, Data warehouse appliances, Data warehousing, Infobright, Kickfire, MySQL, Open source, Theory and architecture | 2 Comments |
Greenplum update — Release 3.3 and so on
I visited Greenplum in early April, and talked with them again last night. As I noted in a separate post, there are a couple of subjects I won’t write about today. But that still leaves me free to cover a number of other points about Greenplum, including:
| Categories: Data warehousing, Database compression, EAI, EII, ETL, ELT, ETLT, Greenplum, MapReduce, Parallelization, PostgreSQL | 9 Comments |
Greenplum will be announcing some stuff
Greenplum is having a webinar Monday to announce “The Next Big Leap in Data Warehousing” (capitalization theirs). The idea they’ll be talking about is a genuinely good one. And off the top of my head I can only think of a few vendors who implemented it before Greenplum, and even fewer who emphasize it explicitly. So if you like webinars, you might want to listen in. I plan to blog about the general concept soon after the 12:01 am Monday embargo lifts. (Uh, guys, it is Monday rather than Tuesday, right?)
| Categories: Data warehousing, Greenplum, Specific users | 1 Comment |
How big are the intelligence agencies’ data warehouses?
Edit: The relevant part of the article cited has now been substantially changed, in line with Jeff Jonas’ remarks in the comment thread below.
Joe Harris linked me to an article that made a rather extraordinary claim:
At another federal agency Jonas worked at (he wouldn’t say which), they had a very large data warehouse in the basement. The size of the data warehouse was a secret, but Jonas estimated it at 4 exabytes (EB), and increasing at the rate of 5 TB per day.
Now, if one does the division, the quote claims it takes 800,000 days for the database to double in size, which is absurd. Perhaps this (Jeff) Jonas guy was just talking about a 4 petabyte system and got confused. (Of course, that would still be pretty big.) But before I got my arithmetic straight, I ran the 4 exabyte figure past a couple of folks, as a target for the size of the US government’s largest classified database. Best guess turns out to be that it’s 1-2 orders of magnitude too high for the government’s largest database, not 3. But that’s only a guess …
| Categories: Data warehousing, Specific users | 5 Comments |
Facebook’s experiences with compression
One little topic didn’t make it into my long post on Facebook’s Hadoop/Hive-based data warehouse: Compression. The story seems to be:
- Facebook uses gzip, and gets a little bit more than 6X compression.
- Experiments suggest bzip2 would reduce data by another 20% or so, increasing compression to the 7.5X range.
- The downside of bzip2 is 15-25% processing overhead, depending on the kind of data.
| Categories: Data warehousing, Database compression, Facebook and Cassandra, Hadoop | 2 Comments |
How much state is saved when an MPP DBMS node fails?
Mark Callaghan raised an interesting question in the comment thread to my recent Facebook/Hadoop/Hive post:
My question is about how commercial MPP RDBMS vendors recover from single or a small number of node failures during a long running SQL query. Do any of them save enough state to avoid starting the query over?
Honestly, I’d just be guessing at the answer.
Would any vendors or other knowledgeable folks care to take a crack at answering directly?
| Categories: Data warehousing, Parallelization | 10 Comments |
