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84 lines
2.9 KiB
Python
84 lines
2.9 KiB
Python
from fixtures.log_helper import log
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from fixtures.neon_fixtures import NeonEnv
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#
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# Test that the VM bit is cleared correctly at a HEAP_DELETE and
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# HEAP_UPDATE record.
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#
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def test_vm_bit_clear(neon_simple_env: NeonEnv):
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env = neon_simple_env
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env.neon_cli.create_branch("test_vm_bit_clear", "empty")
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pg = env.postgres.create_start("test_vm_bit_clear")
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log.info("postgres is running on 'test_vm_bit_clear' branch")
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pg_conn = pg.connect()
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cur = pg_conn.cursor()
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# Install extension containing function needed for test
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cur.execute("CREATE EXTENSION neon_test_utils")
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# Create a test table and freeze it to set the VM bit.
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cur.execute("CREATE TABLE vmtest_delete (id integer PRIMARY KEY)")
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cur.execute("INSERT INTO vmtest_delete VALUES (1)")
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cur.execute("VACUUM FREEZE vmtest_delete")
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cur.execute("CREATE TABLE vmtest_update (id integer PRIMARY KEY)")
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cur.execute("INSERT INTO vmtest_update SELECT g FROM generate_series(1, 1000) g")
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cur.execute("VACUUM FREEZE vmtest_update")
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# DELETE and UPDATE the rows.
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cur.execute("DELETE FROM vmtest_delete WHERE id = 1")
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cur.execute("UPDATE vmtest_update SET id = 5000 WHERE id = 1")
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# Branch at this point, to test that later
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env.neon_cli.create_branch("test_vm_bit_clear_new", "test_vm_bit_clear")
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# Clear the buffer cache, to force the VM page to be re-fetched from
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# the page server
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cur.execute("SELECT clear_buffer_cache()")
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# Check that an index-only scan doesn't see the deleted row. If the
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# clearing of the VM bit was not replayed correctly, this would incorrectly
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# return deleted row.
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cur.execute(
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"""
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set enable_seqscan=off;
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set enable_indexscan=on;
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set enable_bitmapscan=off;
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"""
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)
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cur.execute("SELECT * FROM vmtest_delete WHERE id = 1")
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assert cur.fetchall() == []
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cur.execute("SELECT * FROM vmtest_update WHERE id = 1")
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assert cur.fetchall() == []
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cur.close()
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# Check the same thing on the branch that we created right after the DELETE
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#
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# As of this writing, the code in smgrwrite() creates a full-page image whenever
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# a dirty VM page is evicted. If the VM bit was not correctly cleared by the
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# earlier WAL record, the full-page image hides the problem. Starting a new
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# server at the right point-in-time avoids that full-page image.
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pg_new = env.postgres.create_start("test_vm_bit_clear_new")
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log.info("postgres is running on 'test_vm_bit_clear_new' branch")
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pg_new_conn = pg_new.connect()
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cur_new = pg_new_conn.cursor()
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cur_new.execute(
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"""
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set enable_seqscan=off;
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set enable_indexscan=on;
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set enable_bitmapscan=off;
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"""
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)
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cur_new.execute("SELECT * FROM vmtest_delete WHERE id = 1")
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assert cur_new.fetchall() == []
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cur_new.execute("SELECT * FROM vmtest_update WHERE id = 1")
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assert cur_new.fetchall() == []
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