I am now sitting in on MySQL and Search at Craigslist by Jeremy Zawodny at MySQL Users Conference
Some of the technical difficulties that required addressing.
- High churn rate
- half life can be very short
- Growth
- Traffic
- Need to archive postings, e.g. 100M but be searchable
- Internationalization and UTF-8
Some of the Craigslist Goals
- Open Source
- Easy and approachable
- be green with energy use
A review of the Internals server configuration
- Load Balancer (perlbal like)
- Read Proxy Array (perl+memcached)
- Web Read Array (apache 1.3 + mod_perl)
- Object Cache (Perl + memcached)
- Read DB Cluster (MySQL 5.0.x)
- Search Cluster (Sphinx)
Clusters of DB servers have good vertical partitioning by Roles. These being
- Users
- Classified
- Forums
- Stats
- Archive
Sphinx is a full standalone full text search that is used. Did compare with Apache Solr, but it seemed more complex and complicated. The Sphinx configuration:
- Partitioned based on cities (people search locally)
- Attributes v Keywords
- Persistent Connections
- Minimal stopword list
- Partition in 2 clusters (1 master, 4 slaves)
The results of implementing Sphinx were:
- decrease in 25 MySQL boxes to 10 sphinx boxes
- no locking
- 1,000+ qps
- 50M queries per day
- Better separation of code
