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80 lines
2.7 KiB
Python
80 lines
2.7 KiB
Python
from fixtures.log_helper import log
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from fixtures.neon_fixtures import NeonEnv, check_restored_datadir_content
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from fixtures.utils import query_scalar
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#
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# Test multixact state after branching
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# Now this test is very minimalistic -
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# it only checks next_multixact_id field in restored pg_control,
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# since we don't have functions to check multixact internals.
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#
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def test_multixact(neon_simple_env: NeonEnv, test_output_dir):
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env = neon_simple_env
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env.neon_cli.create_branch("test_multixact", "empty")
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pg = env.postgres.create_start("test_multixact")
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log.info("postgres is running on 'test_multixact' branch")
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cur = pg.connect().cursor()
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cur.execute(
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"""
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CREATE TABLE t1(i int primary key);
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INSERT INTO t1 select * from generate_series(1, 100);
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"""
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)
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next_multixact_id_old = query_scalar(
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cur, "SELECT next_multixact_id FROM pg_control_checkpoint()"
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)
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# Lock entries using parallel connections in a round-robin fashion.
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nclients = 20
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connections = []
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for i in range(nclients):
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# Do not turn on autocommit. We want to hold the key-share locks.
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conn = pg.connect(autocommit=False)
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connections.append(conn)
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# On each iteration, we commit the previous transaction on a connection,
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# and issue antoher select. Each SELECT generates a new multixact that
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# includes the new XID, and the XIDs of all the other parallel transactions.
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# This generates enough traffic on both multixact offsets and members SLRUs
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# to cross page boundaries.
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for i in range(5000):
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conn = connections[i % nclients]
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conn.commit()
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conn.cursor().execute("select * from t1 for key share")
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# We have multixacts now. We can close the connections.
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for c in connections:
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c.close()
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# force wal flush
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cur.execute("checkpoint")
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cur.execute(
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"SELECT next_multixact_id, pg_current_wal_insert_lsn() FROM pg_control_checkpoint()"
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)
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res = cur.fetchone()
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assert res is not None
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next_multixact_id = res[0]
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lsn = res[1]
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# Ensure that we did lock some tuples
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assert int(next_multixact_id) > int(next_multixact_id_old)
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# Branch at this point
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env.neon_cli.create_branch("test_multixact_new", "test_multixact", ancestor_start_lsn=lsn)
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pg_new = env.postgres.create_start("test_multixact_new")
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log.info("postgres is running on 'test_multixact_new' branch")
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next_multixact_id_new = pg_new.safe_psql(
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"SELECT next_multixact_id FROM pg_control_checkpoint()"
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)[0][0]
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# Check that we restored pg_controlfile correctly
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assert next_multixact_id_new == next_multixact_id
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# Check that we can restore the content of the datadir correctly
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check_restored_datadir_content(test_output_dir, env, pg)
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