Coverage for python/lsst/daf/butler/registry/queries/_builder.py : 17%

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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__ = ("QueryBuilder",)
25from typing import Any, List, Iterable, TYPE_CHECKING
27from sqlalchemy.sql import ColumnElement, and_, literal, bindparam, select, FromClause
28import sqlalchemy.sql
29from sqlalchemy.engine import Connection
31from ...core import (
32 DimensionElement,
33 SkyPixDimension,
34 Dimension,
35 DatasetType,
36 Timespan,
37)
38from ...core.utils import NamedValueSet
40from ._structs import QuerySummary, QueryColumns, QueryParameters, GivenTime
41from ._datasets import DatasetRegistryStorage
42from .expressions import ClauseVisitor
43from ._query import Query
45if TYPE_CHECKING: 45 ↛ 46line 45 didn't jump to line 46, because the condition on line 45 was never true
46 from ..interfaces import DimensionRecordStorageManager
49class QueryBuilder:
50 """A builder for potentially complex queries that join tables based
51 on dimension relationships.
53 Parameters
54 ----------
55 connection : `sqlalchemy.engine.Connection`
56 SQLAlchemy connection object. This is only used to pass through
57 to the `Query` object returned by `finish`.
58 summary : `QuerySummary`
59 Struct organizing the dimensions involved in the query.
60 dimensionStorage : `DimensionRecordStorageManager`
61 Manager for storage backend objects that abstract access to dimension
62 tables.
63 datasetStorage : `DatasetRegistryStorage`
64 Storage backend object that abstracts access to dataset tables.
65 """
67 def __init__(self, connection: Connection, summary: QuerySummary,
68 dimensionStorage: DimensionRecordStorageManager,
69 datasetStorage: DatasetRegistryStorage):
70 self.summary = summary
71 self._connection = connection
72 self._dimensionStorage = dimensionStorage
73 self._datasetStorage = datasetStorage
74 self._sql = None
75 self._elements: NamedValueSet[DimensionElement] = NamedValueSet()
76 self._columns = QueryColumns()
78 def hasDimensionKey(self, dimension: Dimension) -> bool:
79 """Return `True` if the given dimension's primary key column has
80 been included in the query (possibly via a foreign key column on some
81 other table).
82 """
83 return dimension in self._columns.keys
85 def joinDimensionElement(self, element: DimensionElement):
86 """Add the table for a `DimensionElement` to the query.
88 This automatically joins the element table to all other tables in the
89 query with which it is related, via both dimension keys and spatial
90 and temporal relationships.
92 External calls to this method should rarely be necessary; `finish` will
93 automatically call it if the `DimensionElement` has been identified as
94 one that must be included.
96 Parameters
97 ----------
98 element : `DimensionElement`
99 Element for which a table should be added. The element must be
100 associated with a database table (see `DimensionElement.hasTable`).
101 """
102 assert element not in self._elements, "Element already included in query."
103 storage = self._dimensionStorage[element]
104 storage.join(
105 self,
106 regions=self._columns.regions if element in self.summary.spatial else None,
107 timespans=self._columns.timespans if element in self.summary.temporal else None,
108 )
109 self._elements.add(element)
111 def joinDataset(self, datasetType: DatasetType, collections: Any, *,
112 isResult: bool = True, addRank: bool = False):
113 """Add a dataset search or constraint to the query.
115 Unlike other `QueryBuilder` join methods, this *must* be called
116 directly to search for datasets of a particular type or constrain the
117 query results based on the exists of datasets. However, all dimensions
118 used to identify the dataset type must have already been included in
119 `QuerySummary.requested` when initializing the `QueryBuilder`.
121 Parameters
122 ----------
123 datasetType : `DatasetType`
124 The type of datasets to search for.
125 collections : sequence of `str` or `Like`, or ``...``
126 An expression describing the collections in which to search for
127 the datasets. This may be a single instance of or an iterable of
128 any of the following:
130 - a `str` collection name;
131 - a `Like` pattern to match against collection names;
132 - `...`, indicating all collections.
133 isResult : `bool`, optional
134 If `True` (default), include the ``dataset_id`` column in the
135 result columns of the query, allowing complete `DatasetRef`
136 instances to be produced from the query results for this dataset
137 type. If `False`, the existence of datasets of this type is used
138 only to constrain the data IDs returned by the query.
139 addRank : `bool`, optional
140 If `True` (`False` is default), also include a calculated column
141 that ranks the collection in which the dataset was found (lower
142 is better). Requires that all entries in ``collections`` be
143 regular strings, so there is a clear search order. Ignored if
144 ``isResult`` is `False`.
145 """
146 assert datasetType.dimensions.issubset(self.summary.requested)
147 table = self._datasetStorage.getDatasetSubquery(datasetType, collections=collections,
148 isResult=isResult, addRank=addRank)
149 self.joinTable(table, datasetType.dimensions)
150 if isResult:
151 self._columns.datasets[datasetType] = (table.columns["dataset_id"],
152 table.columns["rank"] if addRank else None)
154 def joinTable(self, table: FromClause, dimensions: Iterable[Dimension]):
155 """Join an arbitrary table to the query via dimension relationships.
157 External calls to this method should only be necessary for tables whose
158 records represent neither dataset nor dimension elements (i.e.
159 extensions to the standard `Registry` schema).
161 Parameters
162 ----------
163 table : `sqlalchemy.sql.FromClause`
164 SQLAlchemy object representing the logical table (which may be a
165 join or subquery expression) to be joined.
166 dimensions : iterable of `Dimension`
167 The dimensions that relate this table to others that may be in the
168 query. The table must have columns with the names of the
169 dimensions.
170 """
171 joinOn = self.startJoin(table, dimensions, dimensions.names)
172 self.finishJoin(table, joinOn)
174 def startJoin(self, table: FromClause, dimensions: Iterable[Dimension], columnNames: Iterable[str]
175 ) -> List[ColumnElement]:
176 """Begin a join on dimensions.
178 Must be followed by call to `finishJoin`.
180 Parameters
181 ----------
182 table : `sqlalchemy.sql.FromClause`
183 SQLAlchemy object representing the logical table (which may be a
184 join or subquery expression) to be joined.
185 dimensions : iterable of `Dimension`
186 The dimensions that relate this table to others that may be in the
187 query. The table must have columns with the names of the
188 dimensions.
189 columnNames : iterable of `str`
190 Names of the columns that correspond to dimension key values; must
191 be `zip` iterable with ``dimensions``.
193 Returns
194 -------
195 joinOn : `list` of `sqlalchemy.sql.ColumnElement`
196 Sequence of boolean expressions that should be combined with AND
197 to form (part of) the ON expression for this JOIN.
198 """
199 joinOn = []
200 for dimension, columnName in zip(dimensions, columnNames):
201 columnInTable = table.columns[columnName]
202 columnsInQuery = self._columns.keys.setdefault(dimension, [])
203 for columnInQuery in columnsInQuery:
204 joinOn.append(columnInQuery == columnInTable)
205 columnsInQuery.append(columnInTable)
206 return joinOn
208 def finishJoin(self, table, joinOn):
209 """Complete a join on dimensions.
211 Must be preceded by call to `startJoin`.
213 Parameters
214 ----------
215 table : `sqlalchemy.sql.FromClause`
216 SQLAlchemy object representing the logical table (which may be a
217 join or subquery expression) to be joined. Must be the same object
218 passed to `startJoin`.
219 joinOn : `list` of `sqlalchemy.sql.ColumnElement`
220 Sequence of boolean expressions that should be combined with AND
221 to form (part of) the ON expression for this JOIN. Should include
222 at least the elements of the list returned by `startJoin`.
223 """
224 if joinOn:
225 self._sql = self._sql.join(table, and_(*joinOn))
226 elif self._sql is None:
227 self._sql = table
228 else:
229 # New table is completely unrelated to all already-included
230 # tables. We need a cross join here but SQLAlchemy does not
231 # have a specific method for that. Using join() without
232 # `onclause` will try to join on FK and will raise an exception
233 # for unrelated tables, so we have to use `onclause` which is
234 # always true.
235 self._sql = self._sql.join(table, literal(True) == literal(True))
237 def _joinMissingDimensionElements(self):
238 """Join all dimension element tables that were identified as necessary
239 by `QuerySummary` and have not yet been joined.
241 For internal use by `QueryBuilder` only; will be called (and should
242 only by called) by `finish`.
243 """
244 # Join all DimensionElement tables that we need for spatial/temporal
245 # joins/filters or a nontrivial WHERE expression.
246 # We iterate over these in *reverse* topological order to minimize the
247 # number of tables joined. For example, the "visit" table provides
248 # the primary key value for the "instrument" table it depends on, so we
249 # don't need to join "instrument" as well unless we had a nontrivial
250 # expression on it (and hence included it already above).
251 for element in self.summary.universe.sorted(self.summary.mustHaveTableJoined, reverse=True):
252 self.joinDimensionElement(element)
253 # Join in any requested Dimension tables that don't already have their
254 # primary keys identified by the query.
255 for dimension in self.summary.universe.sorted(self.summary.mustHaveKeysJoined, reverse=True):
256 if dimension not in self._columns.keys:
257 self.joinDimensionElement(dimension)
259 def _addWhereClause(self):
260 """Add a WHERE clause to the query under construction, connecting all
261 joined dimensions to the expression and given dimensions from
262 `QuerySummary`.
264 For internal use by `QueryBuilder` only; will be called (and should
265 only by called) by `finish`.
266 """
267 parameters = QueryParameters()
268 whereTerms = []
269 if self.summary.expression.tree is not None:
270 visitor = ClauseVisitor(self.summary.universe, self._columns, self._elements)
271 whereTerms.append(self.summary.expression.tree.visit(visitor))
272 for dimension, columnsInQuery in self._columns.keys.items():
273 if dimension in self.summary.given:
274 if self.summary.whenIsDimensionGiven(dimension) == GivenTime.AT_EXECUTION:
275 givenKey = bindparam(f"_given_later_{dimension.name}")
276 parameters.keys[dimension] = givenKey
277 else:
278 givenKey = self.summary.dataId[dimension]
279 # Add a WHERE term for each column that corresponds to each
280 # key. This is redundant with the JOIN ON clauses that make
281 # them equal to each other, but more constraints have a chance
282 # of making things easier on the DB's query optimizer.
283 for columnInQuery in columnsInQuery:
284 whereTerms.append(columnInQuery == givenKey)
285 else:
286 # Dimension is not fully identified, but it might be a skypix
287 # dimension that's constrained by a given region.
288 if self.summary.given.spatial and isinstance(dimension, SkyPixDimension):
289 if self.summary.whenIsRegionGiven() == GivenTime.AT_CONSTRUCTION:
290 # We know the region now.
291 givenSkyPixIds = []
292 for begin, end in dimension.pixelization.envelope(self.summary.dataId.region):
293 givenSkyPixIds.extend(range(begin, end))
294 else:
295 # We'll know the region later (there might be a region
296 # now, too, but we'll know a more precise one later,
297 # and hence we'll ignore the one we know now).
298 givenSkyPixIds = bindparam(f"_given_later_{dimension.name}")
299 parameters.skypix[dimension] = givenSkyPixIds
300 for columnInQuery in columnsInQuery:
301 whereTerms.append(columnInQuery.in_(givenSkyPixIds))
302 # If we are [to be] given an dataId with a timespan, and there are
303 # one or more timespans in the query that aren't given, add a WHERE
304 # expression for each of them.
305 if self.summary.given.temporal and self.summary.temporal:
306 if self.summary.whenIsTimespanGiven() == GivenTime.AT_CONSTRUCTION:
307 # Timespan is known now.
308 givenInterval = self.summary.dataId.timespan
309 else:
310 # We'll know the timespan later (there might be a timespan now,
311 # too, but we'll know a more precise one later, and hence we'll
312 # ignore the one we know now).
313 givenInterval = Timespan(
314 begin=bindparam(f"_given_later_timespan_begin"),
315 end=bindparam(f"_given_later_timespan_end"),
316 )
317 for element, intervalInQuery in self._columns.timespans.items():
318 assert element not in self.summary.given.elements
319 whereTerms.append(intervalInQuery.overlaps(givenInterval, ops=sqlalchemy.sql))
320 # AND-together the full WHERE clause, and combine it with the FROM
321 # clause.
322 self._sql = self._sql.where(and_(*whereTerms))
323 return parameters
325 def _addSelectClause(self):
326 """Add a SELECT clause to the query under construction containing all
327 output columns identified by the `QuerySummary` and requested in calls
328 to `joinDataset` with ``isResult=True``.
330 For internal use by `QueryBuilder` only; will be called (and should
331 only by called) by `finish`.
332 """
333 columns = []
334 for dimension in self.summary.requested:
335 columns.append(self._columns.getKeyColumn(dimension))
336 for datasetType, columnPair in self._columns.datasets.items():
337 columns.extend(columnPair)
338 for element, column in self._columns.regions.items():
339 columns.append(column)
340 self._sql = select(columns).select_from(self._sql)
342 def finish(self) -> Query:
343 """Finish query constructing, returning a new `Query` instance.
345 This automatically joins any missing dimension element tables
346 (according to the categorization of the `QuerySummary` the builder was
347 constructed with).
349 This consumes the `QueryBuilder`; no other methods should be called
350 after this one.
352 Returns
353 -------
354 query : `Query`
355 A `Query` object that can be executed (possibly multiple times
356 with different bind parameter values) and used to interpret result
357 rows.
358 """
359 self._joinMissingDimensionElements()
360 self._addSelectClause()
361 parameters = self._addWhereClause()
362 return Query(summary=self.summary, connection=self._connection,
363 sql=self._sql, columns=self._columns, parameters=parameters)