MapReduce
Analysis of implementations of and issues associated with the parallel programming framework MapReduce. Related subjects include:
Cloudera Altus
I talked with Cloudera before the recent release of Altus. In simplest terms, Cloudera’s cloud strategy aspires to:
- Provide all the important advantages of on-premises Cloudera.
- Provide all the important advantages of native cloud offerings such as Amazon EMR (Elastic MapReduce, or at least come sufficiently close to that goal.
- Benefit from customers’ desire to have on-premises and cloud deployments that work:
- Alike in any case.
- Together, to the extent that that makes use-case sense.
In other words, Cloudera is porting its software to an important new platform.* And this port isn’t complete yet, in that Altus is geared only for certain workloads. Specifically, Altus is focused on “data pipelines”, aka data transformation, aka “data processing”, aka new-age ETL (Extract/Transform/Load). (Other kinds of workload are on the roadmap, including several different styles of Impala use.) So what about that is particularly interesting? Well, let’s drill down.
*Or, if you prefer, improving on early versions of the port.
| Categories: Amazon and its cloud, Cloud computing, Cloudera, Databricks, Spark and BDAS, Hadoop, Log analysis, MapReduce, Software as a Service (SaaS) | 2 Comments |
Notes on Spark and Databricks — generalities
I visited Databricks in early July to chat with Ion Stoica and Reynold Xin. Spark also comes up in a large fraction of the conversations I have. So let’s do some catch-up on Databricks and Spark. In a nutshell:
- Spark is indeed the replacement for Hadoop MapReduce.
- Spark is becoming the default platform for machine learning.
- SparkSQL (nee’ Shark) is puttering along predictably.
- Databricks reports good success in its core business of cloud-based machine learning support.
- Spark Streaming has strong adoption, but its position is at risk.
- Databricks, the original authority on Spark, is not keeping a tight grip on that role.
I shall explain below. I also am posting separately about Spark evolution, especially Spark 2.0. I’ll also talk a bit in that post about Databricks’ proprietary/closed-source technology.
Spark is the replacement for Hadoop MapReduce.
This point is so obvious that I don’t know what to say in its support. The trend is happening, as originally decreed by Cloudera (and me), among others. People are rightly fed up with the limitations of MapReduce, and — niches perhaps aside — there are no serious alternatives other than Spark.
The greatest use for Spark seems to be the same as the canonical first use for MapReduce: data transformation. Also in line with the Spark/MapReduce analogy: Read more
| Categories: Cloudera, Databricks, Spark and BDAS, EAI, EII, ETL, ELT, ETLT, Hadoop, MapReduce, Market share and customer counts, Predictive modeling and advanced analytics | 6 Comments |
Readings in Database Systems
Mike Stonebraker and Larry Ellison have numerous things in common. If nothing else:
- They’re both titanic figures in the database industry.
- They both gave me testimonials on the home page of my business website.
- They both have been known to use the present tense when the future tense would be more accurate. 🙂
I mention the latter because there’s a new edition of Readings in Database Systems, aka the Red Book, available online, courtesy of Mike, Joe Hellerstein and Peter Bailis. Besides the recommended-reading academic papers themselves, there are 12 survey articles by the editors, and an occasional response where, for example, editors disagree. Whether or not one chooses to tackle the papers themselves — and I in fact have not dived into them — the commentary is of great interest.
But I would not take every word as the gospel truth, especially when academics describe what they see as commercial market realities. In particular, as per my quip in the first paragraph, the data warehouse market has not yet gone to the extremes that Mike suggests,* if indeed it ever will. And while Joe is close to correct when he says that the company Essbase was acquired by Oracle, what actually happened is that Arbor Software, which made Essbase, merged with Hyperion Software, and the latter was eventually indeed bought by the giant of Redwood Shores.**
*When it comes to data warehouse market assessment, Mike seems to often be ahead of the trend.
**Let me interrupt my tweaking of very smart people to confess that my own commentary on the Oracle/Hyperion deal was not, in retrospect, especially prescient.
Mike pretty much opened the discussion with a blistering attack against hierarchical data models such as JSON or XML. To a first approximation, his views might be summarized as: Read more
Hadoop generalities
Occasionally I talk with an astute reporter — there are still a few left 🙂 — and get led toward angles I hadn’t considered before, or at least hadn’t written up. A blog post may then ensue. This is one such post.
There is a group of questions going around that includes:
- Is Hadoop overhyped?
- Has Hadoop adoption stalled?
- Is Hadoop adoption being delayed by skills shortages?
- What is Hadoop really good for anyway?
- Which adoption curves for previous technologies are the best analogies for Hadoop?
To a first approximation, my responses are: Read more
Teradata will support Presto
At the highest level:
- Presto is, roughly speaking, Facebook’s replacement for Hive, at least for queries that are supposed to run at interactive speeds.
- Teradata is announcing support for Presto with a classic open source pricing model.
- Presto will also become, roughly speaking, Teradata’s replacement for Hive.
- Teradata’s Presto efforts are being conducted by the former Hadapt.
Now let’s make that all a little more precise.
Regarding Presto (and I got most of this from Teradata)::
- To a first approximation, Presto is just another way to write SQL queries against HDFS (Hadoop Distributed File System). However …
- … Presto queries other data stores too, such as various kinds of RDBMS, and federates query results.
- Facebook at various points in time created both Hive and now Presto.
- Facebook started the Presto project in 2012 and now has 10 engineers on it.
- Teradata has named 16 engineers – all from Hadapt – who will be contributing to Presto.
- Known serious users of Presto include Facebook, Netflix, Groupon and Airbnb. Airbnb likes Presto well enough to have 1/3 of its employees using it, via an Airbnb-developed tool called Airpal.
- Facebook is known to have a cluster cited at 300 petabytes and 4000 users where Presto is presumed to be a principal part of the workload.
Daniel Abadi said that Presto satisfies what he sees as some core architectural requirements for a modern parallel analytic RDBMS project: Read more
Notes on indexes and index-like structures
Indexes are central to database management.
- My first-ever stock analyst report, in 1982, correctly predicted that index-based DBMS would supplant linked-list ones …
- … and to this day, if one wants to retrieve a small fraction of a database, indexes are generally the most efficient way to go.
- Recently, I’ve had numerous conversations in which indexing strategies played a central role.
Perhaps it’s time for a round-up post on indexing. 🙂
1. First, let’s review some basics. Classically:
- An index is a DBMS data structure that you probe to discover where to find the data you really want.
- Indexes make data retrieval much more selective and hence faster.
- While indexes make queries cheaper, they make writes more expensive — because when you write data, you need to update your index as well.
- Indexes also induce costs in database size and administrative efforts. (Manual index management is often the biggest hurdle for “zero-DBA” RDBMS installations.)
2. Further: Read more
| Categories: Data warehousing, Database compression, GIS and geospatial, Google, MapReduce, McObject, MemSQL, MySQL, ScaleDB, solidDB, Sybase, Text, Tokutek and TokuDB | 18 Comments |
Where the innovation is
I hoped to write a reasonable overview of current- to medium-term future IT innovation. Yeah, right. 🙂 But if we abandon any hope that this post could be comprehensive, I can at least say:
1. Back in 2011, I ranted against the term Big Data, but expressed more fondness for the V words — Volume, Velocity, Variety and Variability. That said, when it comes to data management and movement, solutions to the V problems have generally been sketched out.
- Volume has been solved. There are Hadoop installations with 100s of petabytes of data, analytic RDBMS with 10s of petabytes, general-purpose Exadata sites with petabytes, and 10s/100s of petabytes of analytic Accumulo at the NSA. Further examples abound.
- Velocity is being solved. My recent post on Hadoop-based streaming suggests how. In other use cases, velocity is addressed via memory-centric RDBMS.
- Variety and Variability have been solved. MongoDB, Cassandra and perhaps others are strong NoSQL choices. Schema-on-need is in earlier days, but may help too.
2. Even so, there’s much room for innovation around data movement and management. I’d start with:
- Product maturity is a huge issue for all the above, and will remain one for years.
- Hadoop and Spark show that application execution engines:
- Have a lot of innovation ahead of them.
- Are tightly entwined with data management, and with data movement as well.
- Hadoop is due for another refactoring, focused on both in-memory and persistent storage.
- There are many issues in storage that can affect data technologies as well, including but not limited to:
- Solid-state (flash or post-flash) vs. spinning disk.
- Networked vs. direct-attached.
- Virtualized vs. identifiable-physical.
- Object/file/block.
- Graph analytics and data management are still confused.
3. As I suggested last year, data transformation is an important area for innovation. Read more
Hadoop’s next refactoring?
I believe in all of the following trends:
- Hadoop is a Big Deal, and here to stay.
- Spark, for most practical purposes, is becoming a big part of Hadoop.
- Most servers will be operated away from user premises, whether via SaaS (Software as a Service), co-location, or “true” cloud computing.
Trickier is the meme that Hadoop is “the new OS”. My thoughts on that start:
- People would like this to be true, although in most cases only as one of several cluster computing platforms.
- Hadoop, when viewed as an operating system, is extremely primitive.
- Even so, the greatest awkwardness I’m seeing when different software shares a Hadoop cluster isn’t actually in scheduling, but rather in data interchange.
There is also a minor issue that if you distribute your Hadoop work among extra nodes you might have to pay a bit more to your Hadoop distro support vendor. Fortunately, the software industry routinely solves more difficult pricing problems than that.
| Categories: Cloud computing, Databricks, Spark and BDAS, Hadoop, MapReduce, MemSQL, Software as a Service (SaaS) | 15 Comments |
Thoughts and notes, Thanksgiving weekend 2014
I’m taking a few weeks defocused from work, as a kind of grandpaternity leave. That said, the venue for my Dances of Infant Calming is a small-but-nice apartment in San Francisco, so a certain amount of thinking about tech industries is inevitable. I even found time last Tuesday to meet or speak with my clients at WibiData, MemSQL, Cloudera, Citus Data, and MongoDB. And thus:
1. I’ve been sloppy in my terminology around “geo-distribution”, in that I don’t always make it easy to distinguish between:
- Storing different parts of a database in different geographies, often for reasons of data privacy regulatory compliance.
- Replicating an entire database into different geographies, often for reasons of latency and/or availability/ disaster recovery,
The latter case can be subdivided further depending on whether multiple copies of the data can accept first writes (aka active-active, multi-master, or multi-active), or whether there’s a clear single master for each part of the database.
What made me think of this was a phone call with MongoDB in which I learned that the limit on number of replicas had been raised from 12 to 50, to support the full-replication/latency-reduction use case.
2. Three years ago I posted about agile (predictive) analytics. One of the points was:
… if you change your offers, prices, ad placement, ad text, ad appearance, call center scripts, or anything else, you immediately gain new information that isn’t well-reflected in your previous models.
Subsequently I’ve been hearing more about predictive experimentation such as bandit testing. WibiData, whose views are influenced by a couple of Very Famous Department Store clients (one of which is Macy’s), thinks experimentation is quite important. And it could be argued that experimentation is one of the simplest and most direct ways to increase the value of your data.
3. I’d further say that a number of developments, trends or possibilities I’m seeing are or could be connected. These include agile and experimental predictive analytics in general, as noted in the previous point, along with: Read more
Some stuff on my mind, September 28, 2014
1. I wish I had some good, practical ideas about how to make a political difference around privacy and surveillance. Nothing else we discuss here is remotely as important. I presumably can contribute an opinion piece to, more or less, the technology publication(s) of my choice; that can have a small bit of impact. But I’d love to do better than that. Ideas, anybody?
2. A few thoughts on cloud, colocation, etc.:
- The economies of scale of colocation-or-cloud over operating your own data center are compelling. Most of the reasons you outsource hardware manufacture to Asia also apply to outsourcing data center operation within the United States. (The one exception I can think of is supply chain.)
- The arguments for cloud specifically over colocation are less persuasive. Colo providers can even match cloud deployments in rapid provisioning and elastic pricing, if they so choose.
- Surely not coincidentally, I am told that Rackspace is deemphasizing cloud, reemphasizing colocation, and making a big deal out of Open Compute. In connection with that, Rackspace has pulled back from its leadership role in OpenStack.
- I’m hearing much more mention of Amazon Redshift than I used to. It seems to have a lot of traction as a simple and low-cost option.
- I’m hearing less about Elastic MapReduce than I used to, although I imagine usage is still large and growing.
- In general, I get the impression that progress is being made in overcoming the inherent difficulties in cloud (and even colo) parallel analytic processing. But it all still seems pretty vague, except for the specific claims being made for traction of Redshift, EMR, and so on.
- Teradata recently told me that in colocation pricing, it is common for floor space to be everything, with power not separately metered. But I don’t think that trend is a big deal, as it is not necessarily permanent.
- Cloud hype is of course still with us.
- Other than the above, I stand by my previous thoughts on appliances, clusters and clouds.
3. As for the analytic DBMS industry: Read more