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Solr @ eBay Kleinanzeigen Olaf Zschiedrich, eBay Classifieds Group ozschiedrich@ebay-kleinanzeigen.de, 5/25/2011


Who I am? !  !  !  ! 

Olaf Zschiedrich eBay Classifieds Group Head of Technology @ eBay Kleinanzeigen Area of expertise/interest: •  •  •  • 

High traffic web-applications Agile development Java/JEE Search technologies

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Agenda !  !  !  !  !  !  !  !  !  ! 

About eBay Classifieds Group/ebay Kleinanzeigen Metrics & Traffic Numbers Why Solr? Solr Features in Action Data Indexing Solr in Production Best Practices Problems Outlook Questions 4


About eBay Classifieds Group

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About eBay Classifieds Group

online classifieds company in the world

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About eBay Kleinanzeigen !  Typilcal classifieds ad platform (horizontal, local trading) !  Launched 2009 after 4 months of development !  Small agile team (using Scrum) •  12-15 people total •  5-7 developers

!  Leverages open source (Spring, Solr, MySQL, ActiveMQ) !  Applications: •  •  •  •  • 

Public website Customer support tool API (Rest supporting JSON and XML) Iphone App (~ 250.000 installations) Facebook App 7


Metrics & Traffic Numbers !  Site metrics: •  ~ 3.2 M active ads •  16 – 24 M PVs per day •  Peak hours = 1.8 M PVs (~ 500 PVs per second)

!  Solr request metrics: •  ~ 60 M requests per day •  Peak hours = ~ 1500 request per second

!  Avg. response time •  20 ms (search) and 3 ms for auto-suggest

Site is rapidly growing !!! 8


Why Solr !  !  !  !  !  !  !  !  ! 

Open Source Good documentation / big community Java-based (the language we know/use) Widely used (especially lucene) Based on lucene (de-facto standard for full text search in java) Feature-rich (including enterprise features) Extensible (e.g. easy implementation of own tokenizers) Easy to integrate (HTTP, SolrJ client) Easy to setup (java web application)

Most promising option we looked at. Due to very aggressive timelines no time consuming research was possible! 9


Solr Features in Action !  !  !  !  !  !  !  ! 

Faceting Language specific stemming More Like This Auto-Suggest based on TermComponent Spellchecking Synonyms Stopwords Dynamic fields

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Data Indexing MySQL Slave

JDBC

Solr Master

!  !  ! 

Delta Import Handler

! 

Use of Delta Import Handler Delta import runs every 10 minutes Full import only done in case schema change requires full index rebuild Index optimized once a day

HTTP / REST API Replication Handler

Solr Slave

Solr Slave

Solr Slave

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Solr In Production !  2 datacenters !  1 Master + 6 Slaves per datacenter Slaves show very low resource consumption. Could go down to 4 slaves per datacenter while still having 50% overcapacity

!  !  !  !  ! 

Master only used for indexing Load balancer in front of slaves Varnish in front of slaves (for dedicated use cases) Working closely with SITE-OPS Team DEV-OPS are part of development process

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Solr 3.1 in Production !  Solr 3.1 productive since mid of May !  Not plug and play. Needs migration path as: •  Index format has changed •  Java-bin format has changed

!  Two major problems: •  Bug in spellchecker (SOLR-2462) Leads to infinite GC loops

•  Bug in replication handler (SOLR-2469) Leads to growing disk usage as old index files are not removed is case “replicateAfter=startup” is used.

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Best Practises !  Use solr cores right from the beginning Allows you to run mutiple indexes on one box in dev and distribute indexes to mutiple boxes in production

Use filter queries Use caching (FieldCache, QueryCache, Web Proxy Cache e.g. Varnish or Squid) Tune JVM properly Build search-layer hiding the usage of solr

!  !  !  ! 

SearchCommand cmd = new SearchCommand();
 cmd.setKeywords(“BMW 323“);
 ...
 SearchResult result = searchService.searchActiveAds(cmd);
 List<Ad> ads = result.getAds();

" !  Create a QueryBuilder to ease query building SolrQueryBuilder sqb = new SolrQueryBuilder();
 sqb = sqb.freetext("freetext", "BMW").and().in("color", "RED", "BLACK“);
 sqb = sqb.and().not().eq("fuel_type", "GAS").and().lt(“price“, "10000");
 ...
 String query = sqb.build();
 
 (Just an example. Normally filter queries should be used for a query like this!) 14


Problems !  Distance search including sorting •  Not supported in previous Solr versions •  LocalSolr not working with Solr 1.4 final, GC issues, performance issues

•  Solution: Got rid of sort by distance. Implemented own distance search based on bounding boxes and simple range queries.

•  Solved in 3.1

!  Real time updates !  Deep paging large result sets (SOLR-1726)

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Outlook / Future Plans !  Migrate further applications to Solr Most batch-jobs and customer support tool search against db which is getting slower due to growth of data.

!  Evaluate new features of Solr 3.1 •  Spatial/distance search •  New auto-suggest component •  Extended dismax query parser

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Questions ?

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Contact !  Olaf Zschiedrich •  ozschiedrich@ebay-kleinanzeigen.de •  ozschiedrich@ebay.com •  www.ebay-kleinanzeigen.de

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Zschiedrich Olaf - Solr @ Ebay Kleinanzeigen - read only