Technology behind the Facebook Search [closed]

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Closed 7 years ago.

Improve this question 开发者_高级运维

If you just start typing a person name in the Facebook search box(displayed in blue upper bar on your profile) then suddenly within a fraction of a second search results appear and they comes much more faster if that person already exist in your profile.

so i just want to know that what is behind this search.i mean to say that which software tool and algorithm they are using for it.

i know that no one other than Facebook can explain exactly about it thats why i am just asking to give me an idea about that.

i am sure that they are using something which is open source.

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The response is an autocomplete Ajax form, but this is not really the question. The key question here is how fast can you search in a text field. Facebook splits this into 2 parts. First they search in the list of your friend which is a cached and relatively rarely changed file containing 100 to a 1000 entries. This is quite fast. The other thing is to search for a name in ALL Facebook, which means I guess 1 billion names. This is a little more tricky, but I guess they have them splitted and indexed by letters or letters combinations. For example:

// search query Alice Cooper
A ... they give you a list of A like names Alina, Ana, Alice...
Al .... they limit it to Alicia, Alice, Alina ...
// and so on

Probably after a 3 letters they are starting to do a search, but not in the 1 billion rows, but in a limited subset of your 3rd level friends and probably increasing it each time.

Probably your query is never compared with the whole table, and there are definitely cached levels or recalculated queries for most of the common names.

This is in terms of technique. In terms of technology take a look at Solandra, a search engine build on top of Cassandra which Facebook is using, though I cannot confirm that this is what they are using, but just to give you a research direction.

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I assume the underlying technology is AJAX, with some caching mechanism that increases performance for profiles in your friends list.