Python

Python client for ChronDB, auto-generated from the Rust SDK via UniFFI.

Requirements

• Python 3.8+

Installation

Install directly from the latest GitHub release:

macOS (Apple Silicon):

pip install https://github.com/avelino/chrondb/releases/download/latest/chrondb-latest-py3-none-macosx_14_0_arm64.whl

Linux (x86_64):

pip install https://github.com/avelino/chrondb/releases/download/latest/chrondb-latest-py3-none-manylinux_2_35_x86_64.whl

The wheel already includes the native shared library — no extra configuration needed.

Library path (advanced)

If you need to override the bundled library (e.g., using a custom build), the binding searches in this order:

1. CHRONDB_LIB_PATH — full path to the library file

2. CHRONDB_LIB_DIR — directory containing the library

3. Bundled lib/ inside the package

4. System paths: /usr/local/lib, /usr/lib

export CHRONDB_LIB_PATH=/path/to/libchrondb.so

Quick Start

from chrondb import ChronDB

# Single path (preferred)
with ChronDB("./mydb") as db:
    # Save a document
    db.put("user:1", {"name": "Alice", "age": 30})

    # Retrieve it
    doc = db.get("user:1")
    print(doc)  # {"name": "Alice", "age": 30}

Legacy API (deprecated): ChronDB("/tmp/data", "/tmp/index") still works but is deprecated. Use the single-path form instead.

API Reference

ChronDB(db_path: str, idle_timeout: float = None)

Opens a database connection using a single directory path. Data and index are stored in subdirectories automatically.

Parameter	Type	Description
db_path	str	Path for the database (data and index stored inside)
idle_timeout	Optional[float]	Seconds of inactivity before suspending the GraalVM isolate. None (default) keeps it alive for the entire lifetime.

When idle_timeout is set, the GraalVM isolate is automatically closed after the specified seconds of inactivity, freeing CPU and memory. The next operation transparently reopens it. See Idle Timeout for details.

Raises: ChronDBError if the database cannot be opened.

Implements the context manager protocol (__enter__ / __exit__), calling close() automatically on exit.

Legacy: ChronDB(data_path: str, index_path: str, idle_timeout: float = None)

Deprecated. The two-path constructor still works but is deprecated. Use the single-path form above.

Parameter	Type	Description
data_path	str	Path for the Git repository (data storage)
index_path	str	Path for the Lucene index
idle_timeout	Optional[float]	Seconds of inactivity before suspending the GraalVM isolate

---

put(id, doc, branch=None) -> Dict[str, Any]

Saves a document.

Parameter	Type	Description
id	str	Document ID (e.g., "user:1")
doc	Dict[str, Any]	Document data
branch	Optional[str]	Branch name (None for default)

Returns: The saved document as a dictionary.

Raises: ChronDBError on failure.

---

get(id, branch=None) -> Dict[str, Any]

Retrieves a document by ID.

Parameter	Type	Description
id	str	Document ID
branch	Optional[str]	Branch name

Returns: The document as a dictionary.

Raises: DocumentNotFoundError if not found, ChronDBError on failure.

---

delete(id, branch=None) -> bool

Deletes a document by ID.

Parameter	Type	Description
id	str	Document ID
branch	Optional[str]	Branch name

Returns: True if deleted.

Raises: DocumentNotFoundError if not found, ChronDBError on failure.

---

list_by_prefix(prefix, branch=None) -> List[Dict[str, Any]]

Lists documents whose IDs start with the given prefix.

Parameter	Type	Description
prefix	str	ID prefix to match
branch	Optional[str]	Branch name

Returns: List of matching documents (empty list if none).

---

list_by_table(table, branch=None) -> List[Dict[str, Any]]

Lists all documents in a table.

Parameter	Type	Description
table	str	Table name
branch	Optional[str]	Branch name

Returns: List of matching documents (empty list if none).

---

history(id, branch=None) -> List[Dict[str, Any]]

Returns the change history of a document.

Parameter	Type	Description
id	str	Document ID
branch	Optional[str]	Branch name

Returns: List of history entries (empty list if none).

---

query(query, branch=None) -> Dict[str, Any]

Executes a query against the Lucene index.

Parameter	Type	Description
query	Dict[str, Any]	Query in Lucene AST format
branch	Optional[str]	Branch name

Returns: Results dict with keys results, total, limit, offset.

Raises: ChronDBError on failure.

---

execute(sql, branch=None) -> Dict[str, Any]

Executes a SQL query directly against the database without needing a running server.

Parameter	Type	Description
sql	str	SQL query string
branch	Optional[str]	Branch name (None for default)

Returns: Result dict with keys type, columns, rows, count.

Raises: ChronDBError on failure.

---

close()

Closes the database connection and releases native resources. Called automatically when using the context manager.

Document ID Convention

Documents use the format table:id:

db.put("user:123", {"name": "Alice"})
db.put("order:456", {"total": 99.90})

Internally, user:123 is stored as user/user_COLON_123.json in the Git repository.

Use list_by_table("user") to retrieve all documents in the user table.

Error Handling

Exception Hierarchy

ChronDBError (base)
  └── DocumentNotFoundError

ChronDBError

Base exception for all ChronDB errors (connection failures, operation errors, native library issues).

DocumentNotFoundError

Raised by get() and delete() when the target document does not exist.

Example

from chrondb import ChronDB, ChronDBError, DocumentNotFoundError

try:
    with ChronDB("./mydb") as db:
        doc = db.get("user:999")
except DocumentNotFoundError:
    print("Document does not exist")
except ChronDBError as e:
    print(f"Database error: {e}")

Examples

Full CRUD

from chrondb import ChronDB

with ChronDB("./mydb") as db:
    # Create
    db.put("user:1", {"name": "Alice", "email": "[email protected]"})
    db.put("user:2", {"name": "Bob", "email": "[email protected]"})

    # Read
    alice = db.get("user:1")

    # Update
    alice["age"] = 30
    db.put("user:1", alice)

    # Delete
    db.delete("user:2")

    # List by table
    users = db.list_by_table("user")

    # List by prefix
    matched = db.list_by_prefix("user:1")

Query

with ChronDB("./mydb") as db:
    db.put("product:1", {"name": "Laptop", "price": 999})
    db.put("product:2", {"name": "Mouse", "price": 29})

    results = db.query({
        "type": "term",
        "field": "name",
        "value": "Laptop"
    })
    print(results["total"])  # 1

History (Time Travel)

with ChronDB("./mydb") as db:
    db.put("config:app", {"version": "1.0"})
    db.put("config:app", {"version": "2.0"})

    entries = db.history("config:app")
    for entry in entries:
        print(entry)

SQL Queries

Execute SQL queries directly without needing a running server:

with ChronDB("./mydb") as db:
    db.put("user:1", {"name": "Alice", "age": 30})
    db.put("user:2", {"name": "Bob", "age": 25})

    result = db.execute("SELECT * FROM user")
    print(result["columns"])  # ["name", "age"]
    print(result["count"])    # 2

    result = db.execute("SELECT * FROM user WHERE name = 'Alice'")
    print(result["rows"])     # [{"name": "Alice", "age": 30}]

Idle Timeout (long-running services)

ChronDB loads a GraalVM native-image shared library whose internal threads consume CPU even when no operations are in flight. For long-running services with sporadic database access, use idle_timeout to automatically suspend the isolate when idle:

from chrondb import ChronDB

# Isolate suspends after 2 minutes of inactivity
db = ChronDB("./mydb", idle_timeout=120)

# Normal usage — no change in API
db.put("audit:1", {"action": "login"})
doc = db.get("audit:1")

# After 120s without operations, the GraalVM isolate is torn down.
# The next call to put/get/query transparently reopens it.

When to use:

• Long-running daemons that write to ChronDB intermittently (e.g., audit logging, MCP servers)

• Services where memory/CPU usage matters during idle periods

When NOT to use:

• Short-lived scripts (just use ChronDB(...) without timeout)

• High-throughput services with constant database access (the isolate would never go idle)

Pytest Fixture

import pytest
from chrondb import ChronDB

@pytest.fixture
def db(tmp_path):
    with ChronDB(str(tmp_path / "db")) as conn:
        yield conn

def test_put_and_get(db):
    db.put("item:1", {"value": 42})
    doc = db.get("item:1")
    assert doc["value"] == 42

Building from Source

# 1. Build the shared library (requires Java 11+ and GraalVM)
cd chrondb/
clojure -M:shared

# 2. Install the Python package in development mode
cd bindings/python/
pip install -e .

# 3. Run tests
CHRONDB_LIB_DIR=../../target pytest