Discussion of workload management technology, typically in analytic or mixed-workload DBMS.
It took me a bit of time, and an extra call with Vertica’s long-time R&D chief Shilpa Lawande, but I think I have a decent handle now on Vertica 7, code-named Crane. The two aspects of Vertica 7 I find most interesting are:
- Flex Zone, a schema-on-need technology very much like Hadapt’s (but of course with access to Vertica performance).
- What sounds like an alternate query execution capability for short-request queries, the big point of which is that it saves them from being broadcast across the whole cluster, hence improving scalability. (Adding nodes of course doesn’t buy you much for the portion of a workload that’s broadcast.)
Other Vertica 7 enhancements include:
- A lot of Bottleneck Whack-A-Mole.
- “Significant” improvements to the Vertica management console.
- Security enhancements (Kerberos), Hadoop integration enhancements (HCatalog), and enhanced integration with Hadoop security (Kerberos again).
- Some availability hardening. (“Fault groups”, which for example let you ensure that data is replicated not just to 2+ nodes, but also that the nodes aren’t all on the same rack.)
- Java as an option to do in-database analytics. (Who knew that feature was still missing?)
- Some analytic functionality. (Approximate COUNT DISTINCT, but not yet Approximate MEDIAN.)
Overall, two recurring themes in our discussion were:
- Load and ETL (Extract/Transform/Load) performance, and/or obviating ETL.
- Short-request performance, in the form of more scalable short-request concurrency.
I visited Cloudera Friday for, among other things, a chat about Impala with Marcel Kornacker and colleagues. Highlights included:
- Impala is meant to someday be a competitive MPP (Massively Parallel Processing) analytic RDBMS.
- At the moment, it is not one. For example, Impala lacks any meaningful form of workload management or query optimization.
- While Impala will run against any HDFS (Hadoop Distributed File System) file format, claims of strong performance assume that the data is in Parquet …
- … which is the replacement for the short-lived Trevni …
- … and which for most practical purposes is true columnar.
- Impala is also meant to be more than an RDBMS; Parquet and presumably in the future Impala can accommodate nested data structures.
- Just as Impala runs against most or all HDFS file formats, Parquet files can be used by most Hadoop execution engines, and of course by Pig and Hive.
- The Impala roadmap includes workload management, query optimization, data skipping, user-defined functions, hash distribution, two turtledoves, and a partridge in a pear tree.
Data gets into Parquet via batch jobs only — one reason it’s important that Impala run against multiple file formats — but background format conversion is another roadmap item. A single table can be split across multiple formats — e.g., the freshest data could be in HBase, with the rest is in Parquet.
I had a good chat with IBM about IBM BLU, aka BLU Accelerator or Acceleration. BLU basics start:
- BLU is a part of DB2.
- BLU works like a columnar analytic DBMS.
- If you want to do a join combining BLU and non-BLU tables, all the BLU tables are joined first, and the result set is joined to the other tables by the rest of DB2.
And yes — that means Oracle is now the only major relational DBMS vendor left without a true columnar story.
BLU’s maturity and scalability basics start:
- BLU is coming out in IBM DB2 10.5, this quarter.
- BLU will initially be single-server, but …
- … IBM claims “near-linear” scalability up to 64 cores, and further says that …
- … scale-out for BLU is coming “soon”.
- IBM already thinks all your analytically-oriented DB2 tables should be in BLU.
- IBM describes the first version of BLU as being optimized for 10 TB databases, but capable of handling 20 TB.
BLU technical highlights include: Read more
|Categories: Columnar database management, Data pipelining, Data warehousing, Database compression, IBM and DB2, Workload management||20 Comments|
Well-resourced Silicon Valley start-ups typically announce their existence multiple times. Company formation, angel funding, Series A funding, Series B funding, company launch, product beta, and product general availability may not be 7 different “news events”, but they’re apt to be at least 3-4. Platfora, no exception to this rule, is hitting general availability today, and in connection with that I learned a bit more about what they are up to.
In simplest terms, Platfora offers exploratory business intelligence against Hadoop-based data. As per last weekend’s post about exploratory BI, a key requirement is speed; and so far as I can tell, any technological innovation Platfora offers relates to the need for speed. Specifically, I drilled into Platfora’s performance architecture on the query processing side (and associated data movement); Platfora also brags of rendering 100s of 1000s of “marks” quickly in HTML5 visualizations, but I haven’t a clue as to whether that’s much of an accomplishment in itself.
Platfora’s marketing suggests it obviates the need for a data warehouse at all; for most enterprises, of course, that is a great exaggeration. But another dubious aspect of Platfora marketing actually serves to understate the product’s merits — Platfora claims to have an “in-memory” product, when what’s really the case is that Platfora’s memory-centric technology uses both RAM and disk to manage larger data marts than could reasonably be fit into RAM alone. Expanding on what I wrote about Platfora when it de-stealthed: Read more
|Categories: Business intelligence, Columnar database management, Data warehousing, EAI, EII, ETL, ELT, ETLT, Hadoop, Market share and customer counts, Memory-centric data management, Platfora, Workload management||11 Comments|
Hadoop 2.0/YARN is the first big step in evolving Hadoop beyond a strict Map/Reduce paradigm, in that it at least allows for the possibility of non- or beyond-MapReduce processing engines. While YARN didn’t meet its target of general availability around year-end 2012, Arun Murthy of Hortonworks told me recently that:
- Yahoo is a big YARN user.
- There are other — paying — YARN users.
- YARN general availability is now targeted for well before the end of 2013.
Arun further told me about Tez, the next-generation Hadoop processing engine he’s working on, which he also discussed in a recent blog post:
With the emergence of Apache Hadoop YARN as the basis of next generation data-processing architectures, there is a strong need for an application which can execute a complex DAG [Directed Acyclic Graph] of tasks which can then be shared by Apache Pig, Apache Hive, Cascading and others. The constrained DAG expressible in MapReduce (one set of maps followed by one set of reduces) often results in multiple MapReduce jobs which harm latency for short queries (overhead of launching multiple jobs) and throughput for large-scale queries (too much overhead for materializing intermediate job outputs to the filesystem). With Tez, we introduce a more expressive DAG of tasks, within a single application or job, that is better aligned with the required processing task – thus, for e.g., any given SQL query can be expressed as a single job using Tez.
This is similar to the approach of BDAS Spark:
Rather than being restricted to Maps and Reduces, Spark has more numerous primitive operations, including map, reduce, sample, join, and group-by. You can do these more or less in any order.
although Tez won’t match Spark’s richer list of primitive operations.
More specifically, there will be six primitive Tez operations:
- HDFS (Hadoop Distributed File System) input and output.
- Sorting on input and output (I’m not sure why that’s two operations rather than one).
- Shuffling of input and output (ditto).
A Map step would compound HDFS input, output sorting, and output shuffling; a Reduce step compounds — you guessed it! — input sorting, input shuffling, and HDFS output.
I can’t think of much in the way of algorithms that would be logically impossible in MapReduce yet possible in Tez. Rather, the main point of Tez seems to be performance, performance consistency, response-time consistency, and all that good stuff. Specific advantages that Arun and I talked about included:
- The requirement for materializing (onto disk) intermediate results that you don’t want to is gone. (Yay!)
- Hadoop jobs will step on each other’s toes less. Instead of Maps and Reduces from unrelated jobs getting interleaved, all the operations from a single job will by default be executed in one chunk. (Even so, I see no reason to expect early releases of Tez to do a great job on highly concurrent mixed workload management.)
- Added granularity brings opportunities for additional performance enhancements, for example in the area of sorting. (Arun loves sorts.)
|Categories: Databricks, Spark and BDAS, Hadoop, Hortonworks, MapReduce, Workload management, Yahoo||13 Comments|
I recently complained that the Gartner Magic Quadrant for Data Warehouse DBMS conflates many use cases into one set of rankings. So perhaps now would be a good time to offer some thoughts on how to tell use cases apart. Assuming you know that you really want to manage your analytic database with a relational DBMS, the first questions you ask yourself could be:
- How big is your database? How big is your budget?
- How do you feel about appliances?
- How do you feel about the cloud?
- What are the size and shape of your workload?
- How fresh does the data need to be?
Let’s drill down. Read more
Vertica 6 was recently announced, and so it seemed like a good time to catch up on Vertica features. The main topics I want to address are:
- External tables and the associated new Hadoop connector.
- Online schema evolution.
- Workload management.
- I have some tidbits to add to my June, 2011 coverage of Vertica’s analytic functionality.
- I’ll stand for now on my previous coverage of Vertica’s database organization.
In general, the main themes of Vertica 6 appear to be:
- Enterprise/SaaS-friendliness, high uptime, and so on.
- Improved analytic usefulness.
Let’s do the analytic functionality first. Notes on that include:
- Vertica has extended its user-defined function/analytic procedure/whatever functionality to include user-defined load. (Same SDK, different specific classes.)
- One of the languages Vertica supports is R. But for now, parallel R is limited to “Of course, you can run the same functions and procedures on many nodes at once.”
- Based on community activity around bugs and so on, it seems there are users for Vertica’s JSON-based Twitter sentiment analysis plug-in.
I’ll also take this opportunity to expand on something I wrote about a few vendors — including Vertica — at the end of my post on approximate query results. When I probed how customers of Vertica and other RDBMS-based analytic platform vendors used vendor-proprietary advanced analytic SQL and other analytic capabilities, answers included: Read more
|Categories: Columnar database management, Data warehousing, EAI, EII, ETL, ELT, ETLT, Hadoop, Investment research and trading, Predictive modeling and advanced analytics, SQL/Hadoop integration, Vertica Systems, Workload management||1 Comment|
A lot of confusion seems to have built around the facts:
- Hadoop MapReduce is being opened up into something called MapReduce 2 (MRv2).
- Something called YARN (Yet Another Resource Negotiator) is involved.
- One purpose of the whole thing is to make MapReduce not be required for Hadoop.
- MPI (Message Passing Interface) was mentioned as a paradigmatic example of a MapReduce alternative, yet the MPI/YARN/Hadoop effort is somehow troubled.
- Cloudera shipped YARN in June, yet simultaneously warned people away from actually using it.
Here’s my best effort to make sense of all that, helped by a number of conversations with various Hadoop companies, but most importantly a chat Friday with Arun Murthy and other Hortonworks folks.
- YARN, as an aspect of Hadoop, has two major kinds of benefits:
- The ability to use programming frameworks other than MapReduce.
- Scalability, no matter what programming framework you use.
- The YARN availability story goes:
- YARN is in alpha.
- YARN is expected to be in production at year-end, give or take.
- Cloudera made the marketing decision to include YARN in its June Hadoop distribution release anyway, but advised that it was for experimentation rather than production.
- Hortonworks, in its own June release, only shipped code it advised putting into production.
- My take on the YARN/MPI story goes something like this:
- Numerous people have told me of YARN/MPI delays.
- One person suggested that Greenplum is taking the lead in YARN/MPI integration, but has gotten slow and reclusive, apparently due to some big company-itis.
- I find that credible because of the Greenplum/SAS/MPI connection.
- If I understood Arun correctly, the latency story on Hadoop MapReduce is approximately:
- Arun says that Hadoop’s reputation for taking 10s of seconds to start a Hadoop job is old news. It takes a low single-digit number of seconds.
- However, starting all that Java does take 100s of milliseconds at best — 200 milliseconds in an ideal case, 500 milliseconds more realistically, and that’s just on a single server.
- Thus, if you want human real-time interaction, Hadoop MapReduce is not and likely never will be the way to go. Getting Hadoop MapReduce latencies under a few seconds is likely to be more trouble than it’s worth — because of MapReduce, not because of Hadoop.
- In particular — instead of incurring the overhead of starting processes up, Arun thinks low-latency needs should be met in a different way, namely by serving them from already-running processes. The examples he kept mentioning were the event processing projects Storm (out of Twitter, via an acquisition) and S4 (out of Yahoo).
Shortly before Tuesday’s launch of DB2 10, IBM’s Conor O’Mahony checked in for a relatively non-technical briefing.* More precisely, this is about DB2 for “distributed” systems, aka LUW (Linux/Unix/Windows); some of the features have already been in the mainframe version of DB2 for a while. IBM is graciously permitting me to post the associated DB2 10 announcement slide deck.
*I hope any errors in interpretation are minor.
Major aspects of DB2 10 include new or improved capabilities in the areas of:
- Analytic query performance.
- Data ingest.
- Multi-temperature data management.
- Workload management.
- Graph management/relationship analytics.
- Time-travel, bitemporal features, and bitemporal time-travel.
Of course, there are various other enhancements too, including to security (fine-grained access control), Oracle compatibility, and DB2 pureScale. Everything except the pureScale part is also reflected in IBM InfoSphere Warehouse, which is a near-superset of DB2.*
*Also, the data ingest part isn’t in base DB2.
|Categories: Data warehousing, Database compression, IBM and DB2, RDF and graphs, Solid-state memory, Workload management||6 Comments|
I’d like to survey a few related ideas:
- Enterprises should each have a variety of different analytic data stores.
- Vendors — especially but not only IBM and Teradata — are acknowledging and marketing around the point that enterprises should each have a number of different analytic data stores.
- In addition to having multiple analytic data management technology stacks, it is also desirable to have an agile way to spin out multiple virtual or physical relational data marts using a single RDBMS. Vendors are addressing that need.
- Some observers think that the real essence of analytic data management will be in data integration, not the actual data management.
Here goes. Read more
|Categories: Data warehousing, Database diversity, EAI, EII, ETL, ELT, ETLT, Exadata, Greenplum, Hadoop, Hortonworks, IBM and DB2, Informatica, Netezza, Oracle, Sybase, Teradata, Workload management||11 Comments|