DatabaseDimensionOverlapStorage

class lsst.daf.butler.registry.interfaces.DatabaseDimensionOverlapStorage

Bases: abc.ABC

A base class for objects that manage overlaps between a pair of database-backed dimensions.

Attributes Summary

elements

The pair of elements whose overlaps this object manages.

Methods Summary

clearCaches()	Clear any cached state about which overlaps have been materialized.
digestTables()	Return tables used for schema digest.
initialize(db, elementStorage, …)	Construct an instance of this class using a standardized interface.
make_relation(context, governor_constraints, …)	Return a lsst.daf.relation.Relation that represents the join table.

Attributes Documentation

elements

The pair of elements whose overlaps this object manages.

The order of elements is the same as their ordering within the DimensionUniverse.

Methods Documentation

clearCaches() → None

Clear any cached state about which overlaps have been materialized.

digestTables() → collections.abc.Iterable[sqlalchemy.sql.schema.Table]

Return tables used for schema digest.

Returns:

tables : Iterable [ sqlalchemy.schema.Table ]

Possibly empty set of tables for schema digest calculations.

classmethod initialize(db: Database, elementStorage: tuple[DatabaseDimensionRecordStorage, DatabaseDimensionRecordStorage], governorStorage: tuple[GovernorDimensionRecordStorage, GovernorDimensionRecordStorage], context: StaticTablesContext | None = None) → DatabaseDimensionOverlapStorage

Construct an instance of this class using a standardized interface.

Parameters:

db : Database

Interface to the underlying database engine and namespace.

elementStorage : tuple [ DatabaseDimensionRecordStorage ]

Storage objects for the elements this object will related.

governorStorage : tuple [ GovernorDimensionRecordStorage ]

Storage objects for the governor dimensions of the elements this object will related.

context : StaticTablesContext, optional

If provided, an object to use to create any new tables. If not provided, db.ensureTableExists should be used instead.

Returns:

storage : DatabaseDimensionOverlapStorage

A new DatabaseDimensionOverlapStorage subclass instance.

make_relation(context: queries.SqlQueryContext, governor_constraints: Mapping[str, Set[str]]) → Relation | None

Return a lsst.daf.relation.Relation that represents the join table.

High-level code should generally call DimensionRecordStorageManager.make_spatial_join_relation (which delegates to this) instead of calling this method directly.

Parameters:

context : queries.SqlQueryContext

Object that manages relation engines and database-side state (e.g. temporary tables) for the query.

governor_constraints : Mapping [ str, Set ], optional

Constraints imposed by other aspects of the query on governor dimensions; collections inconsistent with these constraints will be skipped.

Returns:

relation : lsst.daf.relation.Relation or None

Join relation. Should be None when no direct overlaps for this combination are stored; higher-level code is responsible for working out alternative approaches involving multiple joins.