search indexing from postgres

If you mean “how do I create/search indexes for Postgres so searches are fast?”, there are a few common options depending on the type of search:

1) Exact match / filtering

Use a normal B-tree index:

CREATE INDEX idx_users_email ON users(email);

Good for:

SELECT * FROM users WHERE email = 'a@b.com';

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2) Partial match with LIKE

For prefix searches:

CREATE INDEX idx_users_name ON users(name);

Works for:

SELECT * FROM users WHERE name LIKE 'Jo%';

For case-insensitive prefix search, use an expression index:

CREATE INDEX idx_users_name_lower ON users (lower(name));

Query:

SELECT * FROM users WHERE lower(name) LIKE 'jo%';

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3) Full-text search

For searching words in text fields, use PostgreSQL full-text search:

CREATE INDEX idx_articles_fts
ON articles
USING GIN (to_tsvector('english', content));

Query:

SELECT *
FROM articles
WHERE to_tsvector('english', content) @@ plainto_tsquery('english', 'database indexing');

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4) Search across multiple columns

Create a combined full-text index:

CREATE INDEX idx_docs_fts
ON docs
USING GIN (
  to_tsvector('english', coalesce(title, '') || ' ' || coalesce(body, ''))
);

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5) Trigram search

For fuzzy matching / similarity / ILIKE '%term%' style searches, use pg_trgm:

CREATE EXTENSION IF NOT EXISTS pg_trgm;

CREATE INDEX idx_users_name_trgm
ON users
USING GIN (name gin_trgm_ops);

Then:

SELECT * FROM users WHERE name ILIKE '%john%';

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6) JSONB search

If you search inside JSONB fields, index them with GIN:

CREATE INDEX idx_events_data ON events USING GIN (data);

Query:

SELECT * FROM events WHERE data @> '{"type":"click"}';

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How to see if Postgres is using an index

Use:

EXPLAIN ANALYZE
SELECT * FROM users WHERE email = 'a@b.com';

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If you want, I can show:

• the best index for your exact query
• how to sync PostgreSQL indexing with Elasticsearch/OpenSearch
• how to build a search index in PostgreSQL with SQLAlchemy/Django