Coverage for python/lsst/daf/butler/registry/dimensions/query.py : 79%

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1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
21from __future__ import annotations
23__all__ = ["QueryDimensionRecordStorage"]
25from typing import Any, Iterable, Mapping, Optional
27import sqlalchemy
29from ...core import (
30 DatabaseDimension,
31 DatabaseDimensionElement,
32 DataCoordinateIterable,
33 DimensionElement,
34 DimensionRecord,
35 GovernorDimension,
36 NamedKeyDict,
37 NamedKeyMapping,
38 SpatialRegionDatabaseRepresentation,
39 TimespanDatabaseRepresentation,
40)
41from ..interfaces import (
42 Database,
43 DatabaseDimensionRecordStorage,
44 GovernorDimensionRecordStorage,
45 StaticTablesContext,
46)
47from ..queries import QueryBuilder
50class QueryDimensionRecordStorage(DatabaseDimensionRecordStorage):
51 """A read-only record storage implementation backed by SELECT query.
53 At present, the only query this class supports is a SELECT DISTNCT over the
54 table for some other dimension that has this dimension as an implied
55 dependency. For example, we can use this class to provide access to the
56 set of ``band`` names referenced by any ``physical_filter``.
58 Parameters
59 ----------
60 db : `Database`
61 Interface to the database engine and namespace that will hold these
62 dimension records.
63 element : `DatabaseDimensionElement`
64 The element whose records this storage will manage.
65 """
66 def __init__(self, db: Database, element: DatabaseDimensionElement, viewOf: str):
67 assert isinstance(element, DatabaseDimension), \
68 "An element cannot be a dependency unless it is a dimension."
69 self._db = db
70 self._element = element
71 self._target = element.universe[viewOf]
72 self._targetSpec = self._target.RecordClass.fields.makeTableSpec(
73 RegionReprClass=self._db.getSpatialRegionRepresentation(),
74 TimespanReprClass=self._db.getTimespanRepresentation(),
75 )
76 self._viewOf = viewOf
77 self._query = None # Constructed on first use.
78 if element not in self._target.graph.dimensions: 78 ↛ 79line 78 didn't jump to line 79, because the condition on line 78 was never true
79 raise NotImplementedError("Query-backed dimension must be a dependency of its target.")
80 if element.metadata: 80 ↛ 81line 80 didn't jump to line 81, because the condition on line 80 was never true
81 raise NotImplementedError("Cannot use query to back dimension with metadata.")
82 if element.implied: 82 ↛ 83line 82 didn't jump to line 83, because the condition on line 82 was never true
83 raise NotImplementedError("Cannot use query to back dimension with implied dependencies.")
84 if element.alternateKeys: 84 ↛ 85line 84 didn't jump to line 85, because the condition on line 84 was never true
85 raise NotImplementedError("Cannot use query to back dimension with alternate unique keys.")
86 if element.spatial is not None: 86 ↛ 87line 86 didn't jump to line 87, because the condition on line 86 was never true
87 raise NotImplementedError("Cannot use query to back spatial dimension.")
88 if element.temporal is not None: 88 ↛ 89line 88 didn't jump to line 89, because the condition on line 88 was never true
89 raise NotImplementedError("Cannot use query to back temporal dimension.")
91 @classmethod
92 def initialize(
93 cls,
94 db: Database,
95 element: DatabaseDimensionElement, *,
96 context: Optional[StaticTablesContext] = None,
97 config: Mapping[str, Any],
98 governors: NamedKeyMapping[GovernorDimension, GovernorDimensionRecordStorage],
99 ) -> DatabaseDimensionRecordStorage:
100 # Docstring inherited from DatabaseDimensionRecordStorage.
101 viewOf = config["view_of"]
102 return cls(db, element, viewOf)
104 @property
105 def element(self) -> DatabaseDimension:
106 # Docstring inherited from DimensionRecordStorage.element.
107 return self._element
109 def clearCaches(self) -> None:
110 # Docstring inherited from DimensionRecordStorage.clearCaches.
111 pass
113 def _ensureQuery(self) -> None:
114 if self._query is None: 114 ↛ exitline 114 didn't return from function '_ensureQuery', because the condition on line 114 was never false
115 targetTable = self._db.getExistingTable(self._target.name, self._targetSpec)
116 assert targetTable is not None
117 columns = []
118 # The only columns for this dimension are ones for its required
119 # dependencies and its own primary key (guaranteed by the checks in
120 # the ctor).
121 for dimension in self.element.required:
122 if dimension == self.element: 122 ↛ 125line 122 didn't jump to line 125, because the condition on line 122 was never false
123 columns.append(targetTable.columns[dimension.name].label(dimension.primaryKey.name))
124 else:
125 columns.append(targetTable.columns[dimension.name].label(dimension.name))
126 # This query doesn't do a SELECT DISTINCT, because that's confusing
127 # and potentially wasteful if we apply a restrictive WHERE clause,
128 # as SelectableDimensionRecordStorage.fetch will do.
129 # Instead, we add DISTINCT in join() only.
130 self._query = sqlalchemy.sql.select(
131 columns, distinct=True
132 ).select_from(
133 targetTable
134 ).alias(
135 self.element.name
136 )
138 def join(
139 self,
140 builder: QueryBuilder, *,
141 regions: Optional[NamedKeyDict[DimensionElement, SpatialRegionDatabaseRepresentation]] = None,
142 timespans: Optional[NamedKeyDict[DimensionElement, TimespanDatabaseRepresentation]] = None,
143 ) -> None:
144 # Docstring inherited from DimensionRecordStorage.
145 assert regions is None, "Should be guaranteed by constructor checks."
146 assert timespans is None, "Should be guaranteed by constructor checks."
147 if self._target in builder.summary.mustHaveKeysJoined: 147 ↛ 152line 147 didn't jump to line 152, because the condition on line 147 was never true
148 # Do nothing; the target dimension is already being included, so
149 # joining against a subquery referencing it would just produce a
150 # more complicated query that's guaranteed to return the same
151 # results.
152 return
153 self._ensureQuery()
154 joinOn = builder.startJoin(self._query, self.element.required,
155 self.element.RecordClass.fields.required.names)
156 builder.finishJoin(self._query, joinOn)
157 return self._query
159 def insert(self, *records: DimensionRecord) -> None:
160 # Docstring inherited from DimensionRecordStorage.insert.
161 raise TypeError(f"Cannot insert {self.element.name} records.")
163 def sync(self, record: DimensionRecord) -> bool:
164 # Docstring inherited from DimensionRecordStorage.sync.
165 raise TypeError(f"Cannot sync {self.element.name} records.")
167 def fetch(self, dataIds: DataCoordinateIterable) -> Iterable[DimensionRecord]:
168 # Docstring inherited from DimensionRecordStorage.fetch.
169 RecordClass = self.element.RecordClass
170 for dataId in dataIds:
171 # Given the restrictions imposed at construction, we know there's
172 # nothing to actually fetch: everything we need is in the data ID.
173 yield RecordClass(**dataId.byName())
175 def digestTables(self) -> Iterable[sqlalchemy.schema.Table]:
176 # Docstring inherited from DimensionRecordStorage.digestTables.
177 return []