使用mysql和php查找短语

Question

I am working on a project and I need your suggestions in a database query. I am using PHP and MySQL.

Context

• I have a table named phrases containing a phrases column in which there are phrases stored, each of which consists of one to three words.
• I have a text string which contains 500 - 1000 words

I need to highlight all the phrases in the text string which exist in my phrases database table.

My solution

I go through every phrase in the phrase list and compare it against the text , but the number of phrases is large (100k) so it takes about 2 min or more to do this matching.

Is there any more efficient way of doing this?

Answer 1

I'm gonna focus on how to do the comparision part with 100K Values. This will require two steps.

a) Write a C++ library and link it to PHP using an extension. Google PHP-CPP. There is a framework which allows you to do this.

b) Inside C/C++ , you need to create a data structure which has a time complexity of O(n) . n being length of the phrases you're searching for. Normally, this is called a tries data structure. This is conventionally used for words without space[not phrases]. but, surely you can write your own.

Here is a link, which contains the word implementation. aka dictionary. http://www.geeksforgeeks.org/trie-insert-and-search/

This takes quite a bit of Memory since, the number is 100K. fair to say, you need a large system. But, when you're looking for better performance, then, Memory tends to be a tradeoff.

Alternative Approach Only PHP. Here , extract phrases from your text input. Convert them into a Hash. the table data that you contain, should also be stored in a hash. [Needs Huge Memory]. The performance here will be rocket fast, per search aka O(1). so, for a sentence of k words. your time complexity will be O(K-factorial).