datus-storage-postgresql 0.1.4

PostgreSQL RDB and pgvector backend adapters for datus-agent

datus-storage-postgresql

PostgreSQL storage adapter for datus-agent. Provides both RDB and Vector backends powered by a single PostgreSQL instance.

Backends

RDB Backend — PostgresRdbBackend

Implements BaseRdbBackend using psycopg v3 and psycopg-pool with a three-layer architecture:

• PostgresRdbBackend (lifecycle): initialize(), connect(namespace, store_db_name), close()
• PgRdbDatabase (database-level, implements RdbDatabase): ensure_table(), transaction(), close()
• PgRdbTable (table-level, implements RdbTable): insert(), query(), update(), delete(), upsert()

Features:

• Full CRUD via PgRdbTable (no need to pass table name)
• upsert() with PostgreSQL ON CONFLICT (dataclass record input)
• transaction() context manager with auto-commit/rollback
• Namespace-based data isolation via PostgreSQL schemas
• Connection pooling with configurable min/max size
• Convenience methods on PgRdbDatabase: get_connection(), execute(), execute_query(), execute_insert()

Vector Backend — PgvectorBackend

Implements BaseVectorBackend using the pgvector extension with a three-layer architecture:

• PgvectorBackend (lifecycle): initialize(), connect(namespace), build_embedding_config(), close()
• PgVectorDb (database-level, implements VectorDatabase): table_exists(), table_names(), create_table(), open_table(), drop_table()
• PgVectorTable (table-level, implements VectorTable): add(), merge_insert(), delete(), update(), search_vector(), search_hybrid(), search_all(), count_rows(), index operations

Features:

• WhereExpr support (condition AST nodes or None) via build_where()
• Vector similarity search (cosine / L2 / inner product)
• Automatic embedding computation on insert
• HNSW vector index, B-tree scalar index, GIN full-text index
• PyArrow Schema to PostgreSQL DDL mapping

Configuration

Both backends register as type: postgresql and accept the same configuration parameters. They can point to the same PostgreSQL instance.

storage:
  rdb:
    type: postgresql
    host: localhost
    port: 5432
    user: postgres
    password: postgres
    dbname: datus
    pool_min_size: 1
    pool_max_size: 10
  vector:
    type: postgresql
    host: localhost
    port: 5432
    user: postgres
    password: postgres
    dbname: datus
    pool_min_size: 1
    pool_max_size: 10

Parameters

Parameter	Required	Default	Description
host	Yes	—	Database host
port	Yes	—	Database port
user	Yes	—	Username
password	Yes	—	Password
dbname	Yes	—	Database name
pool_min_size	No	1	Minimum connections in pool
pool_max_size	No	10	Maximum connections in pool

The vector backend automatically enables the pgvector extension (CREATE EXTENSION IF NOT EXISTS vector) on connect.

Usage

RDB Backend

from dataclasses import dataclass
from datus.storage.rdb.base import TableDefinition, ColumnDef

@dataclass
class User:
    id: int = None
    name: str = None
    email: str = None

backend = PostgresRdbBackend()
backend.initialize(config)

# connect() returns a RdbDatabase handle (namespace maps to PG schema)
db = backend.connect(namespace="my_app", store_db_name="user_store")

# ensure_table() returns a RdbTable handle
users_table = db.ensure_table(TableDefinition(
    table_name="users",
    columns=[
        ColumnDef(name="id", col_type="INTEGER", primary_key=True, autoincrement=True),
        ColumnDef(name="name", col_type="TEXT"),
        ColumnDef(name="email", col_type="TEXT"),
    ],
))

# Table-level CRUD (no need to pass table name)
row_id = users_table.insert(User(name="Alice", email="[e-mail]"))
users = users_table.query(User, where={"name": "Alice"})
users_table.update({"email": "[e-mail]"}, where={"name": "Alice"})
users_table.delete(where={"name": "Alice"})

# Transaction on database level
with db.transaction():
    users_table.insert(User(name="Bob", email="[e-mail]"))
    users_table.insert(User(name="Carol", email="[e-mail]"))

Vector Backend

from datus.storage.conditions import eq, and_

backend = PgvectorBackend()
backend.initialize(config)

# connect() returns a VectorDatabase handle
db = backend.connect(namespace="my_namespace")

# create_table() / open_table() return VectorTable handles
table = db.create_table("my_table", schema=my_schema, embedding_function=emb_config)
table = db.open_table("my_table")

# Table-level operations (no handle passing)
table.add(df)
results = table.search_all(where=eq("category", "active"))
results = table.search_all(where=and_(eq("status", "active"), eq("type", "A")))
results = table.search_vector(query_text="hello", vector_column="vector", top_n=10)

# Database-level operations
db.drop_table("my_table", ignore_missing=True)
assert db.table_exists("my_table") == False

Entry Points

[project.entry-points."datus.storage.rdb"]
postgresql = "datus_storage_postgresql.rdb:register"

[project.entry-points."datus.storage.vector"]
postgresql = "datus_storage_postgresql.vector:register"

Once installed, datus-agent discovers and registers both backends automatically — no manual wiring needed.

Source Layout

datus_storage_postgresql/
├── rdb/
│   ├── __init__.py          # register() → RdbRegistry
│   └── backend.py           # PostgresRdbBackend
└── vector/
    ├── __init__.py           # register() → VectorRegistry
    ├── backend.py            # PgvectorBackend
    └── schema_converter.py   # PyArrow Schema → PostgreSQL DDL