I want to build a keyword search, i saw google app engine api and lucene api but my problem is I have some articles lets say 5000 articles each article have a unique ID, if user search with a keyword then the program should return all the article ID which contains this keyword.
Second thing if user search with a keyword for ex. dress then it should return the articles which contains the keywords dress, dressing, dressed etc.
This is what the Search API is designed for. While it has some limitations, for your basic use case it should suffice. If you want to use Lucene, you will need to run it on another platform (or heavily customise it) because it uses the file system.
For your requirement to find similar words, you can read about stemmed queries here
Use lucene which is a high-performance, full-featured text search engine library. Index each article in different lucene document with unique field article_id. Also index article text in field article_text. Apply StopWordsFilter, PorterStemFilter etc. to field article_text. After indexing you are ready to search keywords.
