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Instead of having a lot of separate fixtures for setting up the page server, the compute nodes, the safekeepers etc., have one big ZenithEnv object that encapsulates the whole environment. Every test either uses a shared "zenith_simple_env" fixture, which contains the default setup of a pageserver with no authentication, and no safekeepers. Tests that want to use safekeepers or authentication set up a custom test-specific ZenithEnv fixture. Gathering information about the whole environment into one object makes some things simpler. For example, when a new compute node is created, you no longer need to pass the 'wal_acceptors' connection string as argument to the 'postgres.create_start' function. The 'create_start' function fetches that information directly from the ZenithEnv object.
69 lines
2.8 KiB
Python
69 lines
2.8 KiB
Python
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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pytest_plugins = ("fixtures.zenith_fixtures")
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#
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# Test where Postgres generates a lot of WAL, and it's garbage collected away, but
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# no pages are evicted so that Postgres uses an old LSN in a GetPage request.
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# We had a bug where the page server failed to find the page version because it
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# thought it was already garbage collected away, because the LSN in the GetPage
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# request was very old and the WAL from that time was indeed already removed.
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# In reality, the LSN on a GetPage request coming from a primary server is
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# just a hint that the page hasn't been modified since that LSN, and the page
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# server should return the latest page version regardless of the LSN.
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#
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def test_old_request_lsn(zenith_simple_env: ZenithEnv):
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env = zenith_simple_env
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# Create a branch for us
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env.zenith_cli(["branch", "test_old_request_lsn", "empty"])
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pg = env.postgres.create_start('test_old_request_lsn')
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log.info('postgres is running on test_old_request_lsn branch')
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pg_conn = pg.connect()
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cur = pg_conn.cursor()
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# Get the timeline ID of our branch. We need it for the 'do_gc' command
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cur.execute("SHOW zenith.zenith_timeline")
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timeline = cur.fetchone()[0]
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psconn = env.pageserver.connect()
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pscur = psconn.cursor()
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# Create table, and insert some rows. Make it big enough that it doesn't fit in
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# shared_buffers.
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cur.execute('CREATE TABLE foo (id int4 PRIMARY KEY, val int, t text)')
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cur.execute('''
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INSERT INTO foo
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SELECT g, 1, 'long string to consume some space' || g
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FROM generate_series(1, 100000) g
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''')
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# Verify that the table is larger than shared_buffers, so that the SELECT below
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# will cause GetPage requests.
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cur.execute('''
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select setting::int * pg_size_bytes(unit) as shared_buffers, pg_relation_size('foo') 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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cur.execute('VACUUM foo')
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# Make a lot of updates on a single row, generating a lot of WAL. Trigger
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# garbage collections so that the page server will remove old page versions.
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for i in range(10):
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pscur.execute(f"do_gc {env.initial_tenant} {timeline} 0")
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for j in range(100):
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cur.execute('UPDATE foo SET val = val + 1 WHERE id = 1;')
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# All (or at least most of) the updates should've been on the same page, so
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# that we haven't had to evict any dirty pages for a long time. Now run
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# a query that sends GetPage@LSN requests with the old LSN.
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cur.execute("SELECT COUNT(*), SUM(val) FROM foo")
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assert cur.fetchone() == (100000, 101000)
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