Coverage for python/lsst/daf/butler/registry/interfaces/_opaque.py: 85%
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5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
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8#
9# This program is free software: you can redistribute it and/or modify
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22"""Interfaces for the objects that manage opaque (logical) tables within a
23`Registry`.
24"""
26from __future__ import annotations
28__all__ = ["OpaqueTableStorageManager", "OpaqueTableStorage"]
30from abc import ABC, abstractmethod
31from collections.abc import Iterable, Iterator, Mapping
32from typing import TYPE_CHECKING, Any
34from ...core.ddl import TableSpec
35from ._database import Database, StaticTablesContext
36from ._versioning import VersionedExtension, VersionTuple
38if TYPE_CHECKING:
39 from ...core.datastore import DatastoreTransaction
42class OpaqueTableStorage(ABC):
43 """An interface that manages the records associated with a particular
44 opaque table in a `Registry`.
46 Parameters
47 ----------
48 name : `str`
49 Name of the opaque table.
50 """
52 def __init__(self, name: str):
53 self.name = name
55 @abstractmethod
56 def insert(self, *data: dict, transaction: DatastoreTransaction | None = None) -> None:
57 """Insert records into the table.
59 Parameters
60 ----------
61 *data
62 Each additional positional argument is a dictionary that represents
63 a single row to be added.
64 transaction : `DatastoreTransaction`, optional
65 Transaction object that can be used to enable an explicit rollback
66 of the insert to be registered. Can be ignored if rollback is
67 handled via a different mechanism, such as by a database. Can be
68 `None` if no external transaction is available.
69 """
70 raise NotImplementedError()
72 @abstractmethod
73 def fetch(self, **where: Any) -> Iterator[Mapping[Any, Any]]:
74 """Retrieve records from an opaque table.
76 Parameters
77 ----------
78 **where
79 Additional keyword arguments are interpreted as equality
80 constraints that restrict the returned rows (combined with AND);
81 keyword arguments are column names and values are the values they
82 must have.
84 Yields
85 ------
86 row : `dict`
87 A dictionary representing a single result row.
88 """
89 raise NotImplementedError()
91 @abstractmethod
92 def delete(self, columns: Iterable[str], *rows: dict) -> None:
93 """Remove records from an opaque table.
95 Parameters
96 ----------
97 columns: `~collections.abc.Iterable` of `str`
98 The names of columns that will be used to constrain the rows to
99 be deleted; these will be combined via ``AND`` to form the
100 ``WHERE`` clause of the delete query.
101 *rows
102 Positional arguments are the keys of rows to be deleted, as
103 dictionaries mapping column name to value. The keys in all
104 dictionaries must be exactly the names in ``columns``.
105 """
106 raise NotImplementedError()
108 name: str
109 """The name of the logical table this instance manages (`str`).
110 """
113class OpaqueTableStorageManager(VersionedExtension):
114 """An interface that manages the opaque tables in a `Registry`.
116 `OpaqueTableStorageManager` primarily serves as a container and factory for
117 `OpaqueTableStorage` instances, which each provide access to the records
118 for a different (logical) opaque table.
120 Notes
121 -----
122 Opaque tables are primarily used by `Datastore` instances to manage their
123 internal data in the same database that hold the `Registry`, but are not
124 limited to this.
126 While an opaque table in a multi-layer `Registry` may in fact be the union
127 of multiple tables in different layers, we expect this to be rare, as
128 `Registry` layers will typically correspond to different leaf `Datastore`
129 instances (each with their own opaque table) in a `ChainedDatastore`.
130 """
132 def __init__(self, *, registry_schema_version: VersionTuple | None = None):
133 super().__init__(registry_schema_version=registry_schema_version)
135 @classmethod
136 @abstractmethod
137 def initialize(
138 cls, db: Database, context: StaticTablesContext, registry_schema_version: VersionTuple | None = None
139 ) -> OpaqueTableStorageManager:
140 """Construct an instance of the manager.
142 Parameters
143 ----------
144 db : `Database`
145 Interface to the underlying database engine and namespace.
146 context : `StaticTablesContext`
147 Context object obtained from `Database.declareStaticTables`; used
148 to declare any tables that should always be present in a layer
149 implemented with this manager.
150 registry_schema_version : `VersionTuple` or `None`
151 Schema version of this extension as defined in registry.
153 Returns
154 -------
155 manager : `OpaqueTableStorageManager`
156 An instance of a concrete `OpaqueTableStorageManager` subclass.
157 """
158 raise NotImplementedError()
160 def __getitem__(self, name: str) -> OpaqueTableStorage:
161 """Interface to `get` that raises `LookupError` instead of returning
162 `None` on failure.
163 """
164 r = self.get(name)
165 if r is None:
166 raise LookupError(f"No logical table with name '{name}' found.")
167 return r
169 @abstractmethod
170 def get(self, name: str) -> OpaqueTableStorage | None:
171 """Return an object that provides access to the records associated with
172 an opaque logical table.
174 Parameters
175 ----------
176 name : `str`
177 Name of the logical table.
179 Returns
180 -------
181 records : `OpaqueTableStorage` or `None`
182 The object representing the records for the given table in this
183 layer, or `None` if there are no records for that table in this
184 layer.
186 Notes
187 -----
188 Opaque tables must be registered with the layer (see `register`) by
189 the same client before they can safely be retrieved with `get`.
190 Unlike most other manager classes, the set of opaque tables cannot be
191 obtained from an existing data repository.
192 """
193 raise NotImplementedError()
195 @abstractmethod
196 def register(self, name: str, spec: TableSpec) -> OpaqueTableStorage:
197 """Ensure that this layer can hold records for the given opaque logical
198 table, creating new tables as necessary.
200 Parameters
201 ----------
202 name : `str`
203 Name of the logical table.
204 spec : `TableSpec`
205 Schema specification for the table to be created.
207 Returns
208 -------
209 records : `OpaqueTableStorage`
210 The object representing the records for the given element in this
211 layer.
213 Notes
214 -----
215 This operation may not be invoked within a transaction context block.
216 """
217 raise NotImplementedError()