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Dllb

dllb

Elixir client for the dllb multi-model NoSQL database

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Dllb provides a high-level Elixir API for communicating with the dllb database over TCP. It manages a NimblePool-based connection pool, speaks the dllb line-based wire protocol, and exposes a query builder plus result parsing so your application can focus on data rather than sockets.

Features

  • Connection pooling—NimblePool-managed TCP sockets with automatic reconnection on dead connections.
  • Wire protocol—Line-based text over TCP; supports JSON, toon, and CSV response formats.
  • Query builder—Composable functions for CREATE, SELECT, UPDATE, DELETE, RELATE, COUNT, upsert (ON CONFLICT UPDATE [SET ...]), DEFINE TABLE/FIELD, and DEFINE/REMOVE INDEX statements.
  • Result structs—Typed structs (Ok, Created, Deleted, Rows, Count, Update, Batch, Communities, Components, Error) parsed from server responses.
  • Secondary indexes—Persisted single- and multi-field (composite) index definitions with optional UNIQUE constraints. Equality and range filters on indexed fields are transparently accelerated by the engine.
  • Full-text & vector search—DEFINE FULLTEXT INDEX (BM25/Tantivy) and DEFINE VECTOR INDEX (HNSW) creation, plus SEARCH and VECTOR SEARCH query builders.
  • MetaAST bridge—Serialization between Metastatic AST 3-tuples and dllb documents/edges, including bulk tree ingestion.
  • Schema bootstrap—Declarative schema definitions executed through any query function.
  • OTP-ready—Application supervision tree with opt-in pool startup via config :dllb, enabled: true.

Installation

Add dllb to your list of dependencies in mix.exs:

def deps do
  [
    {:dllb, "~> 0.1.0"}
  ]
end

Configuration

# config/config.exs
config :dllb,
  enabled: true,
  host: "127.0.0.1",
  port: 3009,
  pool_size: 5,
  outcome: :json,
  timeout: 30_000

Setting enabled: false (the default) starts the application without the connection pool, which is useful for compile-time or test environments where no dllb server is available.

Options

  • :host—server hostname or IP (default "127.0.0.1")
  • :port—server port (default 3009)
  • :pool_size—number of persistent TCP connections (default 5)
  • :outcome—response format: :json, :toon, or :csv (default :json)
  • :timeout—connection and receive timeout in milliseconds (default 30_000)

Usage

Basic queries

{:ok, %Dllb.Result.Rows{count: 3, data: rows}} = Dllb.query("SELECT * FROM users")

result = Dllb.query!("SELECT * FROM users WHERE age > 25")

Query builder

Dllb.Query.create("user", %{name: "Alice", age: 30})
# => "CREATE user SET age = 30, name = 'Alice'"

Dllb.Query.select("user", where: "age > 25", limit: 10)
# => "SELECT * FROM user WHERE age > 25 LIMIT 10"

Dllb.Query.relate("user:a", "follows", "user:b", %{since: "2024"})
# => "RELATE user:a->follows->user:b SET since = '2024'"

Secondary indexes

# Single-field secondary index.
Dllb.Query.define_index("user", "by_age", ["age"])
# => "DEFINE INDEX by_age ON TABLE user FIELDS age"

# Composite index (leftmost-prefix planning: list the leading field first).
Dllb.Query.define_index("ast_node", "idx_file_kind", ["file_path", "kind"])
# => "DEFINE INDEX idx_file_kind ON TABLE ast_node FIELDS file_path, kind"

# Unique constraint over the full indexed tuple.
Dllb.Query.define_index("user", "by_email", ["email"], unique: true)
# => "DEFINE INDEX by_email ON TABLE user FIELDS email UNIQUE"

# Drop an index (queries then fall back to full scans).
Dllb.Query.remove_index("user", "by_age")
# => "REMOVE INDEX by_age ON TABLE user"

Once an index exists, no query changes are required: SELECT, COUNT, and UPDATE statements whose WHERE clause has equality or range predicates on indexed fields are accelerated automatically.

Full-text and vector search

Full-text (BM25) and vector (HNSW) indexes are created over the wire and queried with the SEARCH and VECTOR SEARCH verbs. Both require a dllb server with search services enabled (the default server build).

# Define a full-text index (optionally with a language analyzer).
Dllb.Query.define_fulltext_index("article", "ft_body", "body", analyzer: "english")
# => "DEFINE FULLTEXT INDEX ft_body ON TABLE article FIELDS body ANALYZER english"

# BM25 search; each row carries a "score" field, best-first.
Dllb.Query.search("article", "body", "graph database", limit: 5)
# => "SEARCH article body 'graph database' LIMIT 5"

# Define a vector (HNSW) index over a dense embedding field.
Dllb.Query.define_vector_index("ast_node", "vec_src", "source_embedding", 768, metric: "cosine")
# => "DEFINE VECTOR INDEX vec_src ON TABLE ast_node FIELDS source_embedding DIMENSION 768 METRIC cosine"

# Approximate nearest-neighbour search; each row carries a "distance" field.
Dllb.Query.vector_search("ast_node", "source_embedding", [0.12, 0.07, 0.91], k: 10)
# => "VECTOR SEARCH ast_node source_embedding [0.12, 0.07, 0.91] K 10"

Valid analyzers: default, simple, english, spanish, french, german, italian, portuguese, russian. Valid metrics: cosine, euclidean (alias l2), dot (alias dotproduct/dot_product).

Upserts

# Insert, or merge the same fields on conflict.
Dllb.Query.upsert("user", "u1", %{name: "Alice", age: 30})
# => "CREATE user:u1 SET age = 30, name = 'Alice' ON CONFLICT UPDATE"

# Insert, or apply explicit fields on conflict.
Dllb.Query.upsert("user", "u1", %{name: "Alice", age: 30}, %{age: 31})
# => "CREATE user:u1 SET age = 30, name = 'Alice' ON CONFLICT UPDATE SET age = 31"

Schema bootstrap

{:ok, :bootstrapped} = Dllb.Schema.bootstrap(&Dllb.query/1)

MetaAST ingestion

context = %{language: :elixir, file_path: "/app/lib/parser.ex"}
{:ok, %{nodes: 42, edges: 17}} = Dllb.MetaAST.ingest_tree(ast, context, &Dllb.query/1)

Modules

  • Dllb—top-level query interface (query/1, query!/1)
  • Dllb.Connection—raw TCP socket operations (connect, query, close, alive?)
  • Dllb.Pool—NimblePool connection pool with dead-socket detection
  • Dllb.Protocol—wire format encoding/decoding (line-based text over TCP)
  • Dllb.Query—query string builder for all dllb statement types
  • Dllb.Result—typed structs for parsed server responses
  • Dllb.Schema—declarative schema bootstrap (DEFINE TABLE/FIELD/INDEX)
  • Dllb.MetaAST—Metastatic AST serialization and bulk ingestion
  • Dllb.Error—exception struct with typed error classification

Documentation

hexdocs.pm/dllb

Credits

Created as part of the Oeditus code quality tooling ecosystem.

License

MIT