Yahoo
Discussion of Yahoo’s use of database and analytic technology. Related subjects include:
- The use of analytic technologies to study web and network event data
- (in Text Technologies) Analysis of Yahoo’s efforts as a provider of search and other online services
Facebook, Hadoop, and Hive
I few weeks ago, I posted about a conversation I had with Jeff Hammerbacher of Cloudera, in which he discussed a Hadoop-based effort at Facebook he previously directed. Subsequently, Ashish Thusoo and Joydeep Sarma of Facebook contacted me to expand upon and in a couple of instances correct what Jeff had said. They also filled me in on Hive, a data-manipulation add-on to Hadoop that they developed and subsequently open-sourced.
Updating the metrics in my Cloudera post,
- Facebook has 400 terabytes of disk managed by Hadoop/Hive, with a slightly better than 6:1 overall compression ratio. So the 2 1/2 petabytes figure for user data is reasonable.
- Facebook’s Hadoop/Hive system ingests 15 terabytes of new data per day now, not 10.
- Hadoop/Hive cycle times aren’t as fast as I thought I heard from Jeff. Ad targeting queries are the most frequent, and they’re run hourly. Dashboards are repopulated daily.
Nothing else in my Cloudera post was called out as being wrong.
In a new-to-me metric, Facebook has 610 Hadoop nodes, running in a single cluster, due to be increased to 1000 soon. Facebook thinks this is the second-largest* Hadoop installation, or else close to it. What’s more, Facebook believes it is unusual in spreading all its apps across a single huge cluster, rather than doing different kinds of work on different, smaller sub-clusters.
| Categories: Data warehousing, EAI, EII, ETL, ELT, ETLT, Facebook and Cassandra, Hadoop, MapReduce, Parallelization, Petabyte-scale data management, Specific users, Web analytics, Yahoo | 30 Comments |
Some of Oracle’s largest data warehouses
Googling around, I came across an Oracle presentation – given some time this year – that lists some of Oracle’s largest data warehouses. 10 databases total are listed with >16 TB, which is fairly consistent with Larry Ellison’s confession during the Exadata announcement that Oracle has trouble over 10 TB (which is something I’ve gotten a lot of flack from a few Oracle partisans for pointing out … 
).
However, what’s being measured is probably not the same in all cases. For example, I think the Amazon 70 TB figure is obviously for spinning disk (elsewhere in the presentation it’s stated that Amazon has 71 TB of disk). But the 16 TB British Telecom figure probably is user data — indeed, it’s the same figure Computergram cited for BT user data way back in 2001.
The list is:
| Categories: Data warehousing, Oracle, Specific users, Telecommunications, Yahoo | 2 Comments |
Yahoo scales its web analytics database to petabyte range
Information Week has an article with details on what sounds like Yahoo’s core web analytics database. Highlights include:
- The Yahoo web analytics database is over 1 petabyte. They claim it will be in the 10s of petabytes by 2009.
- The Yahoo web analytics database is based on PostgreSQL. So much for MySQL fanboys’ claims of Yahoo validation for their beloved toy … uh, let me rephrase that. The highly-regarded MySQL, although doing a great job for some demanding and impressive applications at Yahoo, evidently wasn’t selected for this one in particular. OK. That’s much better now.
- But the Yahoo web analytics database doesn’t actually use PostgreSQL’s storage engine. Rather, Yahoo wrote something custom and columnar.
- Yahoo is processing 24 billion “events” per day. The article doesn’t clarify whether these are sent straight to the analytics store, or whether there’s an intermediate storage engine. Most likely the system fills blocks in RAM and then just appends them to the single persistent store. If commodity boxes occasionally crash and lose a few megs of data — well, in this application, that’s not a big deal at all.
- Yahoo thinks commercial column stores aren’t ready yet for more than 100 terabytes of data.
- Yahoo says it got great performance advantages from a custom system by optimizing for its specific application. I don’t know exactly what that would be, but I do know that database architectures for high-volume web analytics are still in pretty bad shape. In particular, there’s no good way yet to analyze the specific, variable-length paths users take through websites.
