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feae7f39c1
Change 'zenith.signal' file to a human-readable format, similar to
backup_label. It can contain a "PREV LSN: %X/%X" line, or a special
value to indicate that it's OK to start with invalid LSN ('none'), or
that it's a read-only node and generating WAL is forbidden
('invalid').
The 'zenith pg create' and 'zenith pg start' commands now take a node
name parameter, separate from the branch name. If the node name is not
given, it defaults to the branch name, so this doesn't break existing
scripts.
If you pass "foo@<lsn>" as the branch name, a read-only node anchored
at that LSN is created. The anchoring is performed by setting the
'recovery_target_lsn' option in the postgresql.conf file, and putting
the server into standby mode with 'standby.signal'.
We no longer store the synthetic checkpoint record in the WAL segment.
The postgres startup code has been changed to use the copy of the
checkpoint record in the pg_control file, when starting in zenith
mode.
96 lines
3.6 KiB
Python
96 lines
3.6 KiB
Python
import subprocess
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from fixtures.zenith_fixtures import PostgresFactory, ZenithPageserver
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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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# Create a couple of branches off the main branch, at a historical point in time.
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#
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def test_branch_behind(zenith_cli, pageserver: ZenithPageserver, postgres: PostgresFactory, pg_bin):
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# Branch at the point where only 100 rows were inserted
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zenith_cli.run(["branch", "test_branch_behind", "empty"])
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pgmain = postgres.create_start('test_branch_behind')
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log.info("postgres is running on 'test_branch_behind' branch")
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main_pg_conn = pgmain.connect()
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main_cur = main_pg_conn.cursor()
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# Create table, and insert the first 100 rows
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main_cur.execute('CREATE TABLE foo (t text)')
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main_cur.execute('''
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INSERT INTO foo
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SELECT 'long string to consume some space' || g
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FROM generate_series(1, 100) g
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''')
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main_cur.execute('SELECT pg_current_wal_insert_lsn()')
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lsn_a = main_cur.fetchone()[0]
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log.info(f'LSN after 100 rows: {lsn_a}')
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# Insert some more rows. (This generates enough WAL to fill a few segments.)
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main_cur.execute('''
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INSERT INTO foo
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SELECT 'long string to consume some space' || g
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FROM generate_series(1, 200000) g
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''')
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main_cur.execute('SELECT pg_current_wal_insert_lsn()')
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lsn_b = main_cur.fetchone()[0]
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log.info(f'LSN after 200100 rows: {lsn_b}')
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# Branch at the point where only 100 rows were inserted
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zenith_cli.run(["branch", "test_branch_behind_hundred", "test_branch_behind@" + lsn_a])
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# Insert many more rows. This generates enough WAL to fill a few segments.
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main_cur.execute('''
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INSERT INTO foo
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SELECT 'long string to consume some space' || g
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FROM generate_series(1, 200000) g
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''')
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main_cur.execute('SELECT pg_current_wal_insert_lsn()')
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main_cur.execute('SELECT pg_current_wal_insert_lsn()')
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lsn_c = main_cur.fetchone()[0]
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log.info(f'LSN after 400100 rows: {lsn_c}')
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# Branch at the point where only 200100 rows were inserted
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zenith_cli.run(["branch", "test_branch_behind_more", "test_branch_behind@" + lsn_b])
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pg_hundred = postgres.create_start("test_branch_behind_hundred")
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pg_more = postgres.create_start("test_branch_behind_more")
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# On the 'hundred' branch, we should see only 100 rows
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hundred_pg_conn = pg_hundred.connect()
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hundred_cur = hundred_pg_conn.cursor()
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hundred_cur.execute('SELECT count(*) FROM foo')
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assert hundred_cur.fetchone() == (100, )
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# On the 'more' branch, we should see 100200 rows
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more_pg_conn = pg_more.connect()
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more_cur = more_pg_conn.cursor()
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more_cur.execute('SELECT count(*) FROM foo')
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assert more_cur.fetchone() == (200100, )
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# All the rows are visible on the main branch
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main_cur.execute('SELECT count(*) FROM foo')
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assert main_cur.fetchone() == (400100, )
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# Check bad lsn's for branching
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# branch at segment boundary
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zenith_cli.run(["branch", "test_branch_segment_boundary", "test_branch_behind@0/3000000"])
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pg = postgres.create_start("test_branch_segment_boundary")
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cur = pg.connect().cursor()
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cur.execute('SELECT 1')
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assert cur.fetchone() == (1, )
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# branch at pre-initdb lsn
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#
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# FIXME: This works currently, but probably shouldn't be allowed
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try:
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zenith_cli.run(["branch", "test_branch_preinitdb", "test_branch_behind@0/42"])
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# FIXME: assert false, "branch with invalid LSN should have failed"
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except subprocess.CalledProcessError:
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log.info("Branch creation with pre-initdb LSN failed (as expected)")
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