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:
Hardware and components — lessons from Teradata
I love talking with Carson Schmidt, chief of Teradata’s hardware engineering (among other things), even if I don’t always understand the details of what he’s talking about. It had been way too long since our last chat, so I requested another one. We were joined by Keith Muller, who I presume is pictured here. Takeaways included:
- Teradata performance growth was slow in the early 2000s, but has accelerated since then; Intel gets a lot of the credit (and blame) for that.
- Carson hopes for a performance “discontinuity” with Intel Ivy Bridge.
- Teradata is not afraid to use niche special-purpose chips.
- Teradata’s views can be taken as well-informed endorsements of InfiniBand and SAS 2.0.
| Categories: Data warehouse appliances, Data warehousing, Database compression, Solid-state memory, Storage, Teradata | 13 Comments |
SAP HANA today
SAP HANA has gotten much attention, mainly for its potential. I finally got briefed on HANA a few weeks ago. While we didn’t have time for all that much detail, it still might be interesting to talk about where SAP HANA stands today.
The HANA section of SAP’s website is a confusing and sometimes inaccurate mess. But an IBM whitepaper on SAP HANA gives some helpful background.
SAP HANA is positioned as an “appliance”. So far as I can tell, that really means it’s a software product for which there are a variety of emphatically-recommended hardware configurations — Intel-only, from what right now are eight usual-suspect hardware partners. Anyhow, the core of SAP HANA is an in-memory DBMS. Particulars include:
- Mainly, HANA is an in-memory columnar DBMS, based on SAP’s confusingly-renamed BI Accelerator/BW Accelerator. Analytics and most OLTP (OnLine Transaction Processing) go against the columnar part of HANA.
- The HANA DBMS also has an in-memory row storage option, used to store metadata, small tables, and so on.
- SAP HANA talks both SQL and MDX.
- The HANA DBMS is shared-nothing across blades or rack servers. I imagine that within an individual blade it’s shared everything. The usual-suspect data distribution or partitioning strategies are available — hash, range, round-robin.
- SAP HANA has what sounds like a natural disk-based persistence strategy — logs, snapshots, and so on. SAP says that this is synchronous enough to give ACID compliance. For some hardware partners, those “disks” are actually Fusion I/O cards.
- HANA is fault-tolerant “across servers”.
- Text support is “coming soon”, which makes sense, given that BI Accelerator was based on the TREX search engine in the first place. Inxight is also in the HANA text mix.
- You can put data into SAP HANA in a variety of obvious ways:
- Writing it directly.
- Trigger-based replication (perhaps from the DBMS that runs your SAP apps).
- Log-based replication (based on Sybase Replication Server).
- SAP Business Objects’ ETL tool.
SAP says that the row-store part is based both on P*Time, an acquisition from Korea some time ago, and also on SAP’s own MaxDB. The IBM white paper mentions only the MaxDB aspect. (Edit: Actually, see the comment thread below.) Based on a variety of clues, I conjecture that this was an aspect of SAP HANA development that did not go entirely smoothly.
Other SAP HANA components include: Read more
Comments on SAS
A reporter interviewed me via IM about how CIOs should view SAS Institute and its products. Naturally, I have edited my comments (lightly) into a blog post. They turned out to be clustered into three groups, as follows:
- SAS faces a number of challenges, not unlike those faced by other high-priced legacy technology vendors.
- It is used by organizations who have large budgets to pay for the product and to pay people to be expert on the product’s intricacies.
- SAS has not integrated with scale-out analytic DBMS technologies as well or quickly as had been hoped, or as earlier marketing suggested was likely.
- SAS has not been strong in helping its users do agile predictive analytics.
- SAS’ strengths are concentrated in product breadth:
- Lots of statistical algorithms.
- Various vertical products that make the modeling techniques more accessible in specific application domains.
- Various approaches to engineering for scalability — no one of those has been a table-thumping success to date, but SAS has the resources to keep trying.
- Some level of integration with its own business intelligence and text analytics products.
- For any particular use case, the burden of proof is on SAS alternatives to show that they have enough pieces in the toolkit to meet the needs.
- SPSS (now owned by IBM) also has legacy issues.
- KXEN is focused on marketing use cases.
- Mahout has been one of the less successful Hadoop-related open source projects.
- R-based technology is still maturing.
- The modeling capabilities (as opposed to just scoring) bundled into RDBMS and well-parallelized tend to be pretty limited. Apparent exceptions tend to just be R repackaged.
| Categories: Analytic technologies, Data warehousing, Hadoop, IBM and DB2, KXEN, Predictive modeling and advanced analytics, SAS Institute | 18 Comments |
Comments on the analytic DBMS industry and Gartner’s Magic Quadrant for same
This year’s Gartner Magic Quadrant for Data Warehouse Database Management Systems is out.* I shall now comment, just as I did on the 2010, 2009, 2008, 2007, and 2006 Gartner Data Warehouse Database Management System Magic Quadrants, to varying extents. To frame the discussion, let me start by saying:
- In general, I regard Gartner Magic Quadrants as a bad use of good research.
- Illustrating the uselessness of — or at least poor execution on — the overall quadrant metaphor, a large majority of the vendors covered are lined up near the line x = y, each outpacing the one below in both of the quadrant’s dimensions.
- I find fewer specifics to disagree with in this Gartner Magic Quadrant than in previous year’s versions. Two factors jump to mind as possible reasons:
- This year’s Gartner Magic Quadrant for Data Warehouse Database Management Systems is somewhat less ambitious than others; while it gives as much company detail as its predecessors, it doesn’t add as much discussion of overall trends. So there’s less to (potentially) disagree with.
- Merv Adrian is now at Gartner.
- Whatever the problems may be with Gartner’s approach, the whole thing comes out better than do Forrester’s failed imitations.
*As of February, 2012 — and surely for many months thereafter — Teradata is graciously paying for a link to the report.
Specific company comments, roughly in line with Gartner’s rough single-dimensional rank ordering, include: Read more
WibiData, derived data, and analytic schema flexibility
My clients at Odiago, vendors of WibiData, have changed their company name simply to WibiData. Even better, they blogged with more detail as to how WibiData works, in what is essentially a follow-on to my original WibiData post last October. Among other virtues, WibiData turns out to be a poster child for my views on derived data and the corresponding schema evolution.
Interesting quotes include:
WibiData is designed to store … transactional data side-by-side with profile and other derived data attributes.
… the ability to add new ad-hoc columns to a table enables more flexible analysis: output data that is the result of one analytic pipeline is stored adjacent to its input data, meaning that you can easily use this as input to second- or third-order derived data as well.
schemas can vary over time; you can easily add a field to a record, or delete a field. … But even though you start collecting that new data, your existing analysis pipelines can treat records like they always did; programs that don’t yet know about the new cookie are still compatible with both the old records already collected, and the new records with the additional field. New programs fill in default values for old data recorded before a field was added, applying the new schema at read time.
schemas for every column are stored in a data dictionary that matches column names with their schemas, as well as human-readable descriptions of the data.
Interesting aspects of the post that don’t lend themselves as well to being excerpted include:
- How the Produce-Gather “analysis calculus” — i.e. framework — works.
- How this all ties into Apache projects (and sub-projects) such as Hadoop, HBase, and Avro.
| Categories: Data models and architecture, Data warehousing, Derived data, NoSQL, WibiData | 3 Comments |
Comments on the 2012 Forrester Wave: Enterprise Hadoop Solutions
Forrester has released its Q1 2012 Forrester Wave: Enterprise Hadoop Solutions. (Googling turns up a direct link, but in case that doesn’t prove stable, here also is a registration-required link from IBM’s Conor O’Mahony.) My comments include:
- The Forrester Wave’s relative vendor rankings are meaningless, in that the document compares apples, peaches, almonds, and peanuts. Apparently, it covers any vendor that includes a distribution of Apache Hadoop MapReduce into something it offers, and that offered at least two (not necessarily full production) references for same.
- The Forrester Wave for “enterprise Hadoop” contradicts itself on the subject of Hortonworks.
- The Forrester Wave for “enterprise Hadoop” is correct when it says “Hortonworks … has Hadoop training and professional services offerings that are still embryonic.”
- Peculiarly, the Forrester Wave for “enterprise Hadoop” also says “Hortonworks offers an impressive Hadoop professional services portfolio”. Hortonworks will likely win one or more nice partnership deals with vendors in adjacent fields, but even so its professional services capabilities are … well, a good word might be “embryonic”.
- Forrester Waves always seem to have weird implicit definitions of “data warehousing”. This one is no exception.
- Forrester gave top marks in “Functionality” to 11 of 13 “enterprise Hadoop” vendors. This seems odd.
- I don’t know why MapR, which doesn’t like HDFS (Hadoop Distributed File System), got top marks in “Subproject integration”.
- Forrester gave top marks in “Storage” to Datameer. It also gave higher marks to MapR than to EMC Greenplum, even though EMC Greenplum’s technology is a superset of MapR’s. Very strange. (Edit: Actually, as per a comment below, there is some uncertainty about the EMC/MapR relationship.)
- Forrester gave higher marks in “Acceleration and optimization” to Hortonworks than to Cloudera and IBM, and higher marks yet to Pentaho. Very odd.
- I’m not sure what Forrester is calling a “Distributed EDW file store connector”, but it sounds like something that Cloudera has provided via partnership to a number of analytic DBMS vendors.
- Forrester’s “Strategy” rankings seem to correlate to a metric of “We’re a large enough vendor to go in N directions at once”, for various values of N.
- Forrester is correct to rank Cloudera’s “Adoption” as being stronger than EMC/Greenplum’s or MapR’s. But Hortonworks’ strong mark for “Adoption” baffles me.
| Categories: Cloudera, Data warehousing, EMC, Greenplum, Hadoop, Hortonworks, MapR, MapReduce, Pentaho | 11 Comments |
Departmental analytics — best practices
I believe IT departments should support and encourage departmental analytics efforts, where “support” and “encourage” are not synonyms for “control”, “dominate”, “overwhelm”, or even “tame”. A big part of that is:
Let, and indeed help, departments have the data they want, when they want it, served with blazing performance.
Three things that absolutely should NOT be obstacles to these ends are:
- Corporate DBMS standards.
- Corporate data governance processes.
- The difficulties of ETL.
| Categories: Business intelligence, Data mart outsourcing, Data warehousing, EAI, EII, ETL, ELT, ETLT, Predictive modeling and advanced analytics | 4 Comments |
Microsoft SQL Server 2012 and enterprise database choices in general
Microsoft is launching SQL Server 2012 on March 7. An IM chat with a reporter resulted, and went something like this.
Reporter: [Care to comment]?
CAM: SQL Server is an adequate product if you don’t mind being locked into the Microsoft stack. For example, the ColumnStore feature is very partial, given that it can’t be updated; but Oracle doesn’t have columnar storage at all.
Reporter: Is the lock-in overall worse than IBM DB2, Oracle?
CAM: Microsoft locks you into an operating system, so yes.
Reporter: Is this release something larger Oracle or IBM shops could consider as a lower-cost alternative a co-habitation scenario, in the event they’re mulling whether to buy more Oracle or IBM licenses?
CAM: If they have a strong Microsoft-stack investment already, sure. Otherwise, why?
Reporter: [How about] just cost?
CAM: DB2 works just as well to keep Oracle honest as SQL Server does, and without a major operating system commitment. For analytic databases you want an analytic DBMS or appliance anyway.
Best is to have one major vendor of OTLP/general-purpose DBMS, a web DBMS, a DBMS for disposable projects (that may be the same as one of the first two), plus however many different analytic data stores you need to get the job done.
By “web DBMS” I mean MySQL, NewSQL, or NoSQL. Actually, you might need more than one product in that area.
| Categories: Data warehousing, IBM and DB2, Microsoft and SQL*Server, Mid-range, MySQL, NoSQL, Oracle | 9 Comments |
Departmental analytics — general observations
Department-level adoption of analytic technology isn’t the exception; it’s the norm. Reasons include:
- Many analytic challenges are inherently departmental.
- In many cases, central IT control of analytics isn’t needed.
- Departments move ahead without central approval or involvement because they can.
That said, arguments for centralizing analytic technology include:
- A lot of data is used by more than one department, for example:
- Financial transactions (one or more affected departments and also the central accounting group).
- Web logs (marketing and IT/web operations).
- Departments may not have the requisite technical expertise (and it may be redundant/cost-ineffective for them to acquire it).
What’s more, there are IT best practices to support department-level analytics. Some of the key ones boil down to:
- Be flexible in your analytic DBMS support.
- Be responsive to requests for ETL.
My conclusion is that central IT should encourage (and aid) departmental analytics. Let’s look at some details.
| Categories: Data warehousing | Leave a Comment |
Splunk update
Splunk is announcing the Splunk 4.3 point release. Before discussing it, let’s recall a few things about Splunk, starting with:
- Splunk is first and foremost an analytic DBMS …
- … used to manage logs and similar multistructured data.
- Splunk’s DML (Data Manipulation Language) is based on text search, not on SQL.
- Splunk has extended its DML in natural ways (e.g., you can use it to do calculations and even some statistics).
- Splunk bundles some (very) basic, Splunk-specific business intelligence capabilities.
- The paradigmatic use of Splunk is to monitor IT operations in real time. However:
- There also are plenty of non-real-time uses for Splunk.
- Splunk is proudest of its growth in non-IT quasi-real-time uses, such as the marketing side of web operations.
As in any release, a lot of Splunk 4.3 is about “Oh, you didn’t have that before?” features and Bottleneck Whack-A-Mole performance speed-up. One performance enhancement is Bloom filters, which are a very hot topic these days. More important is a switch from Flash to HTML5, so as to accommodate mobile devices with less server-side rendering. Splunk reports that its users — especially the non-IT ones — really want to get Splunk information on the tablet devices. While this somewhat contradicts what I wrote a few days ago pooh-poohing mobile BI, let me hasten to point out:
- Splunk is used for a lot of (quasi) real-time monitoring.
- Splunk’s desktop user interfaces are, by BI standards, quite primitive.
That’s pretty much the ideal scenario for mobile BI: Timeliness matters and prettiness doesn’t.