Jiří Materna, Head of Research

The Czech number one Internet company

Seznam.cz

www.seznam.cz

Internet portal with tens of high-quality services:• Web search (web search engine successfully competing with Google)

• Specialized search (Czech companies, e-shops)

• E-mail (the most popular free e-mail in the Czech market)

• News (covering business, politics, lifestyle, sport, whether, TV schedules, etc.)

• Entertainment (video and music online streaming)

• On-line maps (more detailed than Google maps)

• Sklik.cz (advertising system)

• And others…

What is Seznam.cz

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www.seznam.cz

• More than 1000 employees• Revenue 2.8 billion CZK (108 mil. EUR)• 2.4 million people visit Seznam.cz every day• 1.5 billion crawled web pages

-- 45 % English

-- 37 % Czech

-- 7.7 % Slovak

-- 2.3 % German

-- 8 % Others

• 500 queries per second in peak hours

Seznam.cz in numbers

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www.seznam.cz

Search engine architecture

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www.seznam.cz

• Query understanding• Graph representation:

- AND

- OR

- optional

- other relations

Query Expander

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www.seznam.cz

Search aggregators

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• Deduplication• Document sub-results• SERP restrictions• Caching

www.seznam.cz

• RC-Rank – Boosted regression oblivious trees• Hundreds of features• Our own quality measure

Ranking

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www.seznam.cz

Index & Indexer

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• Indexing: complete, daily, fresh

• Data structures:

word barrel – stores the inverted index

document barrel – stores document features

title barrel – stores processed web pages content and metadata

others – query site barrel, site barrel, link barrel, qds barrel, query url barrel, …

www.seznam.cz

• Hadoop, Giraffe, Yarn• 50 mil. documents every day• 1.5 bil. documents out of 50 bil. known

documents stored• duplicity detection

Downloader & document database

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www.seznam.cz

• Joint projects• Providing our technology• Sharing data (MetaCentrum) • …

Possible models of cooperation

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www.seznam.cz

Jiří Materna, Head of Research, jiri.materna@firma.seznam.cz

Thank you for your attention.

@JiriMaterna