Full-Text Search in PostgreSQL

1. Introduction

Full-Text Search (FTS) in PostgreSQL allows for efficient searching of natural language text. It is designed to handle large volumes of text and provides flexibility in querying for specific terms or phrases.

2. Key Concepts

• Text Search Configuration: Defines how text is parsed and indexed.
• Document Types: Supports various document types (e.g., plain text, JSONB).
• Ranking: Ability to rank results based on relevance.
• Vectors: Utilizes tsvector (for text search) and tsquery (for search queries).

3. Implementation

3.1. Setting Up Full-Text Search

CREATE TABLE documents (
    id SERIAL PRIMARY KEY,
    title TEXT,
    body TEXT
);

3.2. Indexing for Full-Text Search

CREATE INDEX idx_gin_title_body ON documents USING GIN(to_tsvector('english', title || ' ' || body));

3.3. Querying with Full-Text Search

SELECT * FROM documents
WHERE to_tsvector('english', title || ' ' || body) @@ to_tsquery('search_term');

3.4. Ranking Results

SELECT *, 
    ts_rank(to_tsvector('english', title || ' ' || body), to_tsquery('search_term')) AS rank
FROM documents
WHERE to_tsvector('english', title || ' ' || body) @@ to_tsquery('search_term')
ORDER BY rank DESC;

4. Best Practices

4.1. Use Appropriate Text Search Configuration

Choose a text search configuration that fits the language and context of your data.

4.2. Regularly Update Statistics

Use ANALYZE to keep your statistics up to date for optimal performance.

4.3. Monitor Index Usage

Check if your indexes are being used effectively and consider partial indexes for large datasets.

5. FAQ