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39 lines
1.4 KiB
Python
39 lines
1.4 KiB
Python
# Test sequential scan speed
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#
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# The test table is large enough (3-4 MB) that it doesn't fit in the compute node
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# cache, so the seqscans go to the page server. But small enough that it fits
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# into memory in the page server.
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from contextlib import closing
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from fixtures.zenith_fixtures import ZenithEnv
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from fixtures.log_helper import log
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from fixtures.benchmark_fixture import MetricReport, ZenithBenchmarker
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from fixtures.compare_fixtures import PgCompare
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pytest_plugins = (
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"fixtures.zenith_fixtures",
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"fixtures.benchmark_fixture",
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"fixtures.compare_fixtures",
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)
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def test_small_seqscans(zenith_with_baseline: PgCompare):
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env = zenith_with_baseline
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with closing(env.pg.connect()) as conn:
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with conn.cursor() as cur:
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cur.execute('create table t (i integer);')
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cur.execute('insert into t values (generate_series(1,100000));')
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# Verify that the table is larger than shared_buffers
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cur.execute('''
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select setting::int * pg_size_bytes(unit) as shared_buffers, pg_relation_size('t') as tbl_ize
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from pg_settings where name = 'shared_buffers'
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''')
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row = cur.fetchone()
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log.info(f"shared_buffers is {row[0]}, table size {row[1]}")
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assert int(row[0]) < int(row[1])
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with env.record_duration('run'):
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for i in range(1000):
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cur.execute('select count(*) from t;')
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