Täistekstindeksite

Täistekstindeksite, known in English as full-text indexes, are data structures designed to enable efficient searching of words within documents. Unlike traditional keyword indexes that only store specific terms, a full-text index stores every word from a document, excluding common words known as stop words (e.g., "the," "a," "is"). This comprehensive approach allows for highly granular searches.

The process of creating a full-text index involves parsing documents, tokenizing them into individual words, and then storing these words along with their locations within the original text. This often involves stemming, where words are reduced to their root form (e.g., "running," "ran," "runs" all become "run"), and lemmatization, which considers the grammatical context to find the base or dictionary form of a word. Inverted indexes are a common implementation, mapping each unique word to a list of documents and positions where it appears.

Full-text indexing is crucial for applications requiring robust search capabilities, such as web search engines, document management systems, and databases. It facilitates searching for phrases, proximity searches (words appearing near each other), and relevance ranking based on word frequency and distribution. The trade-off for this advanced search functionality is the increased storage space required for the index compared to simpler keyword indexes. Efficient algorithms and data structures are employed to manage and query these large indexes effectively.