5dfdb9e481
* New indexes for states table * Added recorder_runs indexes * Created a new function for compound indexes. A new function was created because it makes it a little cleaner when creating a single-field index since one doesn't have to create a list. This is mostly when creating the name of the index so with a bit more logic it's possible to combine it into one function. Given how often migration changes are run, I thought that code bloat was probably a worthy trade-off for now. * Adjusted indexes, POC for ref indexes by name. * Corrected lint errors * Fixed pydocstyle error * Moved create_index function outside apply_update * Moved to single line (just barely)
97 lines
3.7 KiB
Python
97 lines
3.7 KiB
Python
"""Schema migration helpers."""
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import logging
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from .util import session_scope
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_LOGGER = logging.getLogger(__name__)
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def migrate_schema(instance):
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"""Check if the schema needs to be upgraded."""
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from .models import SchemaChanges, SCHEMA_VERSION
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with session_scope(session=instance.get_session()) as session:
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res = session.query(SchemaChanges).order_by(
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SchemaChanges.change_id.desc()).first()
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current_version = getattr(res, 'schema_version', None)
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if current_version == SCHEMA_VERSION:
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return
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_LOGGER.debug("Database requires upgrade. Schema version: %s",
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current_version)
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if current_version is None:
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current_version = _inspect_schema_version(instance.engine, session)
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_LOGGER.debug("No schema version found. Inspected version: %s",
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current_version)
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for version in range(current_version, SCHEMA_VERSION):
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new_version = version + 1
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_LOGGER.info("Upgrading recorder db schema to version %s",
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new_version)
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_apply_update(instance.engine, new_version)
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session.add(SchemaChanges(schema_version=new_version))
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_LOGGER.info("Upgrade to version %s done", new_version)
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def _create_index(engine, table_name, index_name):
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"""Create an index for the specified table.
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The index name should match the name given for the index
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within the table definition described in the models
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"""
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from sqlalchemy import Table
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from . import models
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table = Table(table_name, models.Base.metadata)
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_LOGGER.debug("Looking up index for table %s", table_name)
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# Look up the index object by name from the table is the the models
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index = next(idx for idx in table.indexes if idx.name == index_name)
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_LOGGER.debug("Creating %s index", index_name)
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index.create(engine)
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_LOGGER.debug("Finished creating %s", index_name)
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def _apply_update(engine, new_version):
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"""Perform operations to bring schema up to date."""
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if new_version == 1:
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_create_index(engine, "events", "ix_events_time_fired")
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elif new_version == 2:
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# Create compound start/end index for recorder_runs
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_create_index(engine, "recorder_runs", "ix_recorder_runs_start_end")
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# Create indexes for states
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_create_index(engine, "states", "ix_states_last_updated")
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_create_index(engine, "states", "ix_states_entity_id_created")
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else:
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raise ValueError("No schema migration defined for version {}"
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.format(new_version))
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def _inspect_schema_version(engine, session):
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"""Determine the schema version by inspecting the db structure.
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When the schema verison is not present in the db, either db was just
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created with the correct schema, or this is a db created before schema
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versions were tracked. For now, we'll test if the changes for schema
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version 1 are present to make the determination. Eventually this logic
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can be removed and we can assume a new db is being created.
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"""
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from sqlalchemy.engine import reflection
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from .models import SchemaChanges, SCHEMA_VERSION
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inspector = reflection.Inspector.from_engine(engine)
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indexes = inspector.get_indexes("events")
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for index in indexes:
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if index['column_names'] == ["time_fired"]:
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# Schema addition from version 1 detected. New DB.
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session.add(SchemaChanges(
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schema_version=SCHEMA_VERSION))
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return SCHEMA_VERSION
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# Version 1 schema changes not found, this db needs to be migrated.
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current_version = SchemaChanges(schema_version=0)
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session.add(current_version)
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return current_version.schema_version
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