Computerworld on memory-centric data management
Computerworld recently ran an excellent story on memory-centric data management. The opening sentences show that correspondent Gary Anthes most definitely “gets it”:
Relational database management systems have become all but ubiquitous in enterprise computing since 1970, when they were first devised by E.F. Codd. But as powerful and flexible as those databases are, they’ve proved inadequate for a handful of ultrademanding applications that have to process hundreds or thousands of transactions per second and never go down.
I’m quoted in one of the sidebars, but with the core article being this good I didn’t really add much.
Incidentally, the article talked a lot about Oracle’s recently acquired TimesTen in-memory DBMS product, and also a fair amount about Streambase. This is complementary to my own research, which has focused more on the other leading memory-centric data management vendors.
| Categories: Memory-centric data management, Oracle | Leave a Comment |
DB2 Express-C
IBM announced the freeware version of DB2 today. I’ll post links to the details later, but I want to highlight a couple of interesting implications:
1. They define the cutoff between the free and paid version not by how big a database you can manage on disk, but rather by how much RAM the software can address. This supports my thesis that effective use of RAM is crucial to DBMS performance, and is corollary — specially optimized memory-centric data management products deserve a place in most large enterprises’ product portfolios.
2. Having a free version of DB2 lets one play with whatever features DB2 may have that simply aren’t available in other DBMS, to see if they’re worth using. And the most significant such feature, in my opinion, is native XML storage. Whatever else this product does or doesn’t accomplish, it may serve to speed adoption of IBM’s native XML server technology.
| Categories: IBM and DB2, Memory-centric data management, Mid-range, OLTP, Structured documents | Leave a Comment |
Why I use the word “MOLAP”
“MOLAP” stands for “Multidimensional OLAP.” It’s almost exactly what Ted Codd was referring to in the white paper where he introduced the term “OLAP.” Relational advocates correctly point out that relational tables are NOT “two-dimensional;” rather, every column in a table represents a dimension.
(If that’s not obvious, think of rows in a table as n-tuples, and n-tuples as akin to vectors. Then think back to the linear algebra segment at the beginning of your Calculus of Several Variables class. Vector spaces? Dimensions? I rest my case.)
Despite all that, I’m comfortable with the “M” in MOLAP, because a dimension in a MOLAP hypercube is a lot more complex than a dimension in a relational table. The latter is itself — well, if there’s a sort order, it’s typically one dimensional. But the analog in a MOLAP cube can be a whole rich and complex hierarchy.
So yes — MOLAP is inherently more multidimensional than ROLAP, atlhough one can of course do something equivalent to a single hypercube by creating a whole lot of different tables.
Business rules, business process
Alf Pederson’s blog has yet another long discussion on putting business rules in the database versus putting them in the application. (Since IT Toolbox trackbacks seem to be, as usual, broken, this is the best link I have.)
What’s getting forgotten as usual in this debate, I think, is the direct automation of business processes. Business rules of the sort “No credit granted can exceed $10,000″ are silly whereever they’re put. Rather, the business rule should be something like “An attempt to grant credit in excess of $10,000 is not successful until it has been approved by a VP-level manager.” And the natural way to implement that kind of rule is NOT via database constraints (you need all sorts of other logic around it for usability).
The only “business rules” that belong in the database are precisely those that aren’t really business rules at all.
| Categories: Theory and architecture | 10 Comments |
Detailed webinar on memory-centric technology
I did a webinar on memory-centric data management for Applix. It was the standard hour in length, but they had me do the vast majority of the talking, so I laid out my ideas in some detail.
In line with their business focus, I emphasized OLAP in general and MOLAP in particular. But I did have a chance to lay out pretty much the whole story.
There’s a lot of material in it I haven’t published yet in written form, and some nuances I may never get around to writing down. So if you’re sufficiently interested in the area, I recommend watching the webinar.
| Categories: MOLAP, Memory-centric data management | Leave a Comment |
SAP, MaxDB, and MySQL, updated
I’ve had a chance to clarify and correct my understanding of the relationship between SAP, MaxDB, and MySQL. The story is this:
- MySQL has the right to sell MaxDB, but apparently isn’t focusing much on that.
- The MySQL and MaxDB code lines are NOT merging, for technical reasons. For example, the older MaxDB does a lot of its own thread management, while MySQL relies on the operating system for that.
- When SAP thinks a DBMS is capable of running SAP’s apps, it adds the DBMS to its product catalog and resells it. Yes, even Oracle. That’s why all my discussions with SAP of MySQL’s enterprise-readiness quickly come back to an exhaustive multi-year certification process.
- My personal best guess as to when MySQL will be in SAP’s product catalog is 1 1/2 – 3 years from now.
And by the way, MaxDB’s share in SAP’s user base is about the same as DB2′s (at least DB2 for open systems). MaxDB is being aggressively supported, and nobody should get any ideas to the contrary!
| Categories: IBM and DB2, MySQL, Open source, Oracle, SAP AG | 5 Comments |
Progress DataDirect discovers XML
As a general rule, if you want DBMS drivers, your first call should be to Progress DataDirect. They’ve been the dominant vendor (under multiple names and ownerships) of both ODBC and JDBC drivers, essentially since those standards’ respective inventions. (Persistent Systems Private Ltd. — better known as PSPL — wouldn’t be a terrible choice for your second call).
DataDirect seems to have introduced XQuery drivers last fall. I don’t have a lot of detail on those, however, because the DataDirect guy who contacted me did so mainly to show off a nice toy, Stylus Studio. StylusS tudio is an XML query-building toolkit, available for online purchase for $800 or less. A lot of the users seem to be system integrators. Sales are split 50-50 between the DataDirect regular salesforce and online, apparently mainly from their own store, but I got the sense we’re not talking about huge numbers yet.
In usability when they demoed it to me it looked on a par with Cognos Improptu (a SQL query-building tool) circa the mid-1990s. But they do claim all the right things in round-trip code generation and so on.
Applications seem to be concentrated in intercompany information exchange, based on both legacy EDI (Electronic Data Interchange) and more modern web services. Other uses they cited were parsing web server logs and publishing relational data to a web page.
The technology/product seems to have bounced around for a while, from Object Design (OODBMS pioneer that took a premature shot at the XML database business, and the source of the ObjectStore technology I keep writing about in this blog) to eXcelon (merger partner for ODS, eventually bought by Progress), to Progress’s Sonic Software Division, and now to DataDirect after Progress bought them. Apparently none of those companies have or had top-end UI expertise …
If you want to get a better feel for XQuery, you could do worse than to play with this tool. For example, it’s what I think I’ll use in the unlikely case I ever get around to parsing the SpamAssassin add-ins to my email messages and trying to understand what SpamAssassin is and isn’t doing.
| Categories: Progress, Apama, and DataDirect | Leave a Comment |
More on the inventory database example
In my recent column on XML storage (referenced a couple of posts back), I referenced a Microsoft-provided example of an inventory database. A retailer (I think an online one) wanted to manage books and DVDs and so on, and search across attributes that we common to the different entity kinds, such as title.
Obviously, there are relational alternatives. Items have unique SKU numbers, and they have one of a limited number of kinds, and a set of integrity constraints could mandate that an item was listed in the appropriate table for its kind and no other, and then common attributes could be search on via views that amounted to unions (or derived tables kept synchronized via their own integrity constraints).
I pushed back at Microsoft — which is, you may recall, not just an XML advocate but also one of the largest RDBMS vendors — with this kind of reasoning, and they responded with the following, which I just decided to (with permission) post verbatim.
“If all you ever do is manage books and DVDs, then managing them relationally works well, especially if their properties do not change. However, you many want to add CDs and MP3 on memory cards and many other items that all have different properties. Then you quickly run into an administration overhead and may not be able to keep up with your schema evolution (and you need an additional DBA for managing the complex relational schema). Even if you use a relational approach that stores common properties in joint tables, the recomposition costs of the information for one item may become too expensive to bear.”
| Categories: Microsoft and SQL*Server, Structured documents | 3 Comments |
And now a moment of humor
A classic hacker jest, and also the best blonde joke ever.
| Categories: Humor | 2 Comments |
Finally a column on XML storage
After several months of headfakes, I finally did a column on XML storage this month. There turned out to be room for application discussion, but not for much technical nitty-gritty.
The app discussion is pretty consistent with what I’d already posted here, although I wish I’d gone into more detail on the inventory database example. (Stay tuned for followup here!)
I also intend to post soon with some technical detail about how XML storage is actually handled.
I also got some good insight from Marklogic about what customers wanted in their text-centric markets. More on that soon too.
And by the way — I didn’t pick the Oracle-bashing title. I also didn’t pick the Oracle-bashing title for my Network World “Hot Seat” video. But somehow, the Oracle-doubting parts of my views are of special interest to my friends in the media. And it’s not as if the titles say anything I actually disagree with …
| Categories: OLTP, Oracle, Structured documents | 2 Comments |