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44111e3ba3
This introduces new timeline field latest_gc_cutoff. It is updated before each gc iteration. New check is added to branch_timelines to prevent branch creation with start point less than latest_gc_cutoff. Also this adds a check to get_page_at_lsn which asserts that lsn at which the page is requested was not garbage collected. This check currently is triggered for readonly nodes which are pinned to specific lsn and because they are not tracked in pageserver garbage collection can remove data that still might be referenced. This is a bug and will be fixed separately.
92 lines
3.4 KiB
Python
92 lines
3.4 KiB
Python
import pytest
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from fixtures.log_helper import log
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from fixtures.zenith_fixtures import ZenithEnv
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pytest_plugins = ("fixtures.zenith_fixtures")
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#
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# Create read-only compute nodes, anchored at historical points in time.
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#
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# This is very similar to the 'test_branch_behind' test, but instead of
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# creating branches, creates read-only nodes.
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#
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def test_readonly_node(zenith_simple_env: ZenithEnv):
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env = zenith_simple_env
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env.zenith_cli(["branch", "test_readonly_node", "empty"])
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pgmain = env.postgres.create_start('test_readonly_node')
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log.info("postgres is running on 'test_readonly_node' 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('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('LSN after 200100 rows: ' + lsn_b)
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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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lsn_c = main_cur.fetchone()[0]
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log.info('LSN after 400100 rows: ' + lsn_c)
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# Create first read-only node at the point where only 100 rows were inserted
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pg_hundred = env.postgres.create_start("test_readonly_node_hundred",
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branch=f'test_readonly_node@{lsn_a}')
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# And another at the point where 200100 rows were inserted
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pg_more = env.postgres.create_start("test_readonly_node_more",
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branch=f'test_readonly_node@{lsn_b}')
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# On the 'hundred' node, 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' node, 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 creating a node at segment boundary
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pg = env.postgres.create_start("test_branch_segment_boundary",
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branch="test_readonly_node@0/3000000")
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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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# Create node at pre-initdb lsn
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with pytest.raises(Exception, match='extracting base backup failed'):
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# compute node startup with invalid LSN should fail
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env.zenith_cli(["pg", "start", "test_branch_preinitdb", "test_readonly_node@0/42"])
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