RediSearch

Redlite implements RediSearch-compatible full-text search using SQLite’s FTS5 (Full-Text Search) extension.

Commands

Command	Syntax	Description
FT.CREATE	FT.CREATE index [ON HASH|JSON] SCHEMA field [TEXT|TAG|NUMERIC] ...	Create search index
FT.SEARCH	FT.SEARCH index query [LIMIT offset count]	Search index
FT.INFO	FT.INFO index	Get index information
FT.ALTER	FT.ALTER index SCHEMA ADD field [TEXT|TAG|NUMERIC]	Add field to index
FT.DROPINDEX	FT.DROPINDEX index [DD]	Delete index
FT.EXPLAIN	FT.EXPLAIN index query	Explain query execution
FT.PROFILE	FT.PROFILE index SEARCH query	Profile query performance
FT.AGGREGATE	FT.AGGREGATE index query ...	Aggregate search results

Creating Indexes

Basic Index

# Create index on hash keys matching pattern "doc:*"
127.0.0.1:6379> FT.CREATE idx:docs ON HASH PREFIX 1 doc: SCHEMA title TEXT body TEXT
OK

Index with Multiple Field Types

127.0.0.1:6379> FT.CREATE idx:products ON HASH PREFIX 1 product: SCHEMA name TEXT WEIGHT 5.0 description TEXT category TAG price NUMERIC SORTABLE
OK

Indexing Documents

# Add documents as hashes
127.0.0.1:6379> HSET doc:1 title "Introduction to Databases" body "SQLite is a lightweight database..."
(integer) 2

127.0.0.1:6379> HSET doc:2 title "Redis Guide" body "Redis is an in-memory data store..."
(integer) 2

127.0.0.1:6379> HSET doc:3 title "Database Comparison" body "Comparing SQLite, Redis, and PostgreSQL..."
(integer) 2

Searching

Basic Search

# Search for "database"
127.0.0.1:6379> FT.SEARCH idx:docs "database"
1) (integer) 2
2) "doc:1"
3) 1) "title"
   2) "Introduction to Databases"
   3) "body"
   4) "SQLite is a lightweight database..."
4) "doc:3"
5) 1) "title"
   2) "Database Comparison"
   3) "body"
   4) "Comparing SQLite, Redis, and PostgreSQL..."

Field-Specific Search

# Search in title field only
127.0.0.1:6379> FT.SEARCH idx:docs "@title:redis"
1) (integer) 1
2) "doc:2"
3) 1) "title"
   2) "Redis Guide"
   3) "body"
   4) "Redis is an in-memory data store..."

Boolean Queries

# AND query
127.0.0.1:6379> FT.SEARCH idx:docs "database redis"
1) (integer) 1
2) "doc:3"

# OR query
127.0.0.1:6379> FT.SEARCH idx:docs "sqlite | redis"
1) (integer) 3

# NOT query
127.0.0.1:6379> FT.SEARCH idx:docs "database -redis"
1) (integer) 1
2) "doc:1"

Phrase Search

# Exact phrase
127.0.0.1:6379> FT.SEARCH idx:docs "\"in-memory data store\""
1) (integer) 1
2) "doc:2"

Prefix Search

# Prefix matching
127.0.0.1:6379> FT.SEARCH idx:docs "data*"
1) (integer) 2

Pagination

# Get results 10-20
127.0.0.1:6379> FT.SEARCH idx:docs "database" LIMIT 10 10

TAG Fields

# Create index with tag field
127.0.0.1:6379> FT.CREATE idx:articles ON HASH PREFIX 1 article: SCHEMA title TEXT tags TAG
OK

# Add documents with tags
127.0.0.1:6379> HSET article:1 title "Python Tutorial" tags "programming,python,tutorial"
(integer) 2

# Search by tag
127.0.0.1:6379> FT.SEARCH idx:articles "@tags:{python}"
1) (integer) 1
2) "article:1"

# Multiple tags (OR)
127.0.0.1:6379> FT.SEARCH idx:articles "@tags:{python | javascript}"

# Multiple tags (AND)
127.0.0.1:6379> FT.SEARCH idx:articles "@tags:{python} @tags:{tutorial}"

NUMERIC Fields

# Create index with numeric field
127.0.0.1:6379> FT.CREATE idx:products ON HASH PREFIX 1 product: SCHEMA name TEXT price NUMERIC
OK

# Add products
127.0.0.1:6379> HSET product:1 name "Laptop" price 999.99
(integer) 2
127.0.0.1:6379> HSET product:2 name "Mouse" price 29.99
(integer) 2

# Numeric range query
127.0.0.1:6379> FT.SEARCH idx:products "@price:[0 100]"
1) (integer) 1
2) "product:2"

# Greater than
127.0.0.1:6379> FT.SEARCH idx:products "@price:[500 +inf]"
1) (integer) 1
2) "product:1"

Index Management

Get Index Info

127.0.0.1:6379> FT.INFO idx:docs
 1) "index_name"
 2) "idx:docs"
 3) "index_definition"
 4) 1) "key_type"
    2) "HASH"
    3) "prefixes"
    4) 1) "doc:"
 5) "attributes"
 6) 1) 1) "identifier"
       2) "title"
       3) "type"
       4) "TEXT"
    2) 1) "identifier"
       2) "body"
       3) "type"
       4) "TEXT"
 7) "num_docs"
 8) "3"

Alter Index

# Add new field to existing index
127.0.0.1:6379> FT.ALTER idx:docs SCHEMA ADD author TEXT
OK

Drop Index

# Drop index only (keep documents)
127.0.0.1:6379> FT.DROPINDEX idx:docs
OK

# Drop index and delete documents
127.0.0.1:6379> FT.DROPINDEX idx:docs DD
OK

Aggregation

# Count documents by category
127.0.0.1:6379> FT.AGGREGATE idx:products "*" GROUPBY 1 @category REDUCE COUNT 0 AS count

Query Explanation

# Explain query execution plan
127.0.0.1:6379> FT.EXPLAIN idx:docs "database redis"
1) "AND("
2) "  TERM(database)"
3) "  TERM(redis)"
4) ")"

Performance Profiling

# Profile search query
127.0.0.1:6379> FT.PROFILE idx:docs SEARCH QUERY "database"
1) 1) "Parsing time"
   2) "0.05ms"
2) 1) "Search time"
   2) "0.15ms"

Library Mode (Rust)

use redlite::Db;

let db = Db::open("mydata.db")?;

// Create index
db.ft_create("idx:docs", "HASH", &["doc:"], &[
    ("title", "TEXT"),
    ("body", "TEXT"),
])?;

// Add documents
db.hset("doc:1", &[("title", "Database Guide"), ("body", "...")])?;

// Search
let results = db.ft_search("idx:docs", "database", None, None)?;
for (key, fields) in results {
    println!("{}: {:?}", key, fields);
}

// Drop index
db.ft_dropindex("idx:docs", false)?;

Use Cases

Documentation Search

FT.CREATE idx:docs ON HASH PREFIX 1 doc: SCHEMA title TEXT WEIGHT 5.0 content TEXT tags TAG
FT.SEARCH idx:docs "@tags:{api} @title:authentication"

E-commerce Product Search

FT.CREATE idx:products ON HASH PREFIX 1 product: SCHEMA name TEXT description TEXT category TAG price NUMERIC
FT.SEARCH idx:products "@category:{electronics} @price:[100 500]"

Blog/CMS Search

FT.CREATE idx:posts ON HASH PREFIX 1 post: SCHEMA title TEXT author TEXT content TEXT published NUMERIC
FT.SEARCH idx:posts "@author:john @published:[1704067200 +inf]"

Implementation

• Backend: SQLite FTS5 (Full-Text Search) extension
• Tokenization: Unicode61 tokenizer with case-folding
• Ranking: BM25 ranking algorithm
• Storage: Inverted index in SQLite tables
• Stemming: Porter stemmer support
• Languages: Unicode support for all languages