Source code for terracotta.drivers.sqlite_meta_store


SQLite-backed metadata driver. Metadata is stored in an SQLite database.

import os
from pathlib import Path
from typing import Union

from terracotta.drivers.relational_meta_store import RelationalMetaStore

[docs] class SQLiteMetaStore(RelationalMetaStore): """An SQLite-backed metadata driver. Stores metadata and paths to raster files in SQLite. This is the simplest Terracotta driver, as it requires no additional infrastructure. The SQLite database is simply a file that can e.g. be stored together with the actual raster files. Note: This driver requires the SQLite database to be physically present on the server. For remote SQLite databases hosted on S3, use :class:`~terracotta.drivers.sqlite_remote.RemoteSQLiteDriver`. The SQLite database consists of 4 different tables: - ``terracotta``: Metadata about the database itself. - ``key_names``: Contains two columns holding all available keys and their description. - ``datasets``: Maps key values to physical raster path. - ``metadata``: Contains actual metadata as separate columns. Indexed via key values. This driver caches key names, but not metadata. Warning: This driver is not thread-safe. It is not possible to connect to the database outside the main thread. """ SQL_DIALECT = "sqlite" SQL_DRIVER = "pysqlite" SQL_KEY_SIZE = 256 SQL_TIMEOUT_KEY = "timeout" def __init__(self, path: Union[str, Path]) -> None: """Initialize the SQLiteDriver. This should not be called directly, use :func:`~terracotta.get_driver` instead. Arguments: path: File path to target SQLite database (may or may not exist yet) """ super().__init__(f"{self.SQL_DIALECT}:///{path}") @classmethod def _normalize_path(cls, path: str) -> str: if path.startswith(f"{cls.SQL_DIALECT}:///"): path = path.replace(f"{cls.SQL_DIALECT}:///", "") return os.path.normpath(os.path.realpath(path)) def _create_database(self) -> None: """The database is automatically created by the sqlite driver on connection, so no need to do anything here """ pass