bvandeusenandClaude Opus 5.5
656e127fd8
#5490 "A day of one metric reads fast even cold". A cold 24 h series read measured 18.3 s against 63 ms warm (#5485): every sample's row sat on its own heap page. ix_plugin_metrics_series_value carries `value` (INCLUDE), so the read is an index-only scan; it replaces the plain series index from 0023. It is built once, with CREATE INDEX CONCURRENTLY from a task started after the app is serving, never in a migration, so the boot isn't held while it builds over the live table (#5220) and ingest and pages carry on. A build cut short by a restart leaves an INVALID index; the next boot drops and rebuilds it. Later boots find it present and only check. Postgres keeps it current on each insert, as it did the index it replaces. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
54 lines
2.0 KiB
Python
54 lines
2.0 KiB
Python
"""Integration: the covering series index on plugin_metrics (#5490), built
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after boot against Postgres. It replaces the plain series index, a later boot
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only checks, and a day of one series is then read from the index alone."""
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from __future__ import annotations
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import asyncio
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import logging
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import os
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import pytest
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pytestmark = pytest.mark.integration
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@pytest.fixture
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def app():
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if not os.environ.get("STEWARD_DATABASE_URL"):
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pytest.skip("needs Postgres")
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from steward.app import create_app
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return create_app(testing=False)
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def test_the_series_index_is_built_once_and_replaces_the_plain_one(app):
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from sqlalchemy import text
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from steward.core.metric_index import REPLACES, SERIES_INDEX, ensure_series_index
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log = logging.getLogger("test")
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async def _indexes():
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async with app.db_sessionmaker() as s:
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return dict((await s.execute(text(
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"SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'plugin_metrics'"))).all())
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async def _go():
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first = await ensure_series_index(app._db_engine, log)
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got = await _indexes()
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assert SERIES_INDEX in got and REPLACES not in got
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assert "INCLUDE (value)" in got[SERIES_INDEX]
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assert await ensure_series_index(app._db_engine, log) == "present"
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assert first in ("built", "present")
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# One series over a day is answered from the index alone.
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async with app.db_sessionmaker() as s:
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await s.execute(text("SET enable_seqscan = off"))
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await s.execute(text("SET enable_bitmapscan = off"))
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plan = "\n".join(r[0] for r in (await s.execute(text(
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"EXPLAIN SELECT date_trunc('hour', recorded_at), avg(value) FROM plugin_metrics "
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"WHERE source_module = 'host_agent' AND resource_name = 'x' "
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"AND metric_name = 'cpu_pct' AND recorded_at >= now() - interval '1 day' "
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"GROUP BY 1"))).all())
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assert f"Index Only Scan using {SERIES_INDEX}" in plan, plan
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asyncio.run(_go())
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