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Merged
balloob merged 1 commit into from
Feb 16, 2018
Merged

Optimize recorder purge #12448

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22 changes: 10 additions & 12 deletions homeassistant/components/recorder/purge.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,8 +12,7 @@
def purge_old_data(instance, purge_days, repack):
"""Purge events and states older than purge_days ago."""
from .models import States, Events
from sqlalchemy import orm
from sqlalchemy.sql import exists
from sqlalchemy import func

purge_before = dt_util.utcnow() - timedelta(days=purge_days)
_LOGGER.debug("Purging events before %s", purge_before)
Expand All @@ -22,18 +21,10 @@ def purge_old_data(instance, purge_days, repack):
# For each entity, the most recent state is protected from deletion
# s.t. we can properly restore state even if the entity has not been
# updated in a long time
states_alias = orm.aliased(States, name='StatesAlias')
protected_states = session.query(States.state_id, States.event_id)\
.filter(~exists()
.where(States.entity_id ==
states_alias.entity_id)
.where(states_alias.last_updated >
States.last_updated))\
.all()
protected_states = session.query(func.max(States.state_id)) \
.group_by(States.entity_id).all()

protected_state_ids = tuple((state[0] for state in protected_states))
protected_event_ids = tuple((state[1] for state in protected_states
if state[1] is not None))

deleted_rows = session.query(States) \
.filter((States.last_updated < purge_before)) \
Expand All @@ -46,6 +37,13 @@ def purge_old_data(instance, purge_days, repack):
# Otherwise, if the SQL server has "ON DELETE CASCADE" as default, it
# will delete the protected state when deleting its associated
# event. Also, we would be producing NULLed foreign keys otherwise.
protected_events = session.query(States.event_id) \
.filter(States.state_id.in_(protected_state_ids)) \
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@balloob balloob Feb 18, 2018

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I got a warning from pytest when running the purge tests locally. I think that it is from this line.

tests/components/recorder/test_purge.py::TestRecorderPurge::test_purge_old_events
  /Users/paulus/dev/python/py34-home-assistant/lib/python3.4/site-packages/sqlalchemy/sql/default_comparator.py:161: SAWarning: The IN-predicate on "states.state_id" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate.  Consider alternative strategies for improved performance.
    'strategies for improved performance.' % expr)
  /Users/paulus/dev/python/py34-home-assistant/lib/python3.4/site-packages/sqlalchemy/sql/default_comparator.py:161: SAWarning: The IN-predicate on "events.event_id" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate.  Consider alternative strategies for improved performance.
    'strategies for improved performance.' % expr)

.filter(States.event_id.isnot(None)) \
.all()

protected_event_ids = tuple((state[0] for state in protected_events))

deleted_rows = session.query(Events) \
.filter((Events.time_fired < purge_before)) \
.filter(~Events.event_id.in_(
Expand Down