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https://github.com/neondatabase/neon.git
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257ade0688
This patch aims to:
* Unify connection & querying logic of ZenithPagerserver and Postgres.
* Mitigate changes to transaction machinery introduced in `psycopg2 >= 2.9`.
Now it's possible to acquire db connection using the corresponding
method:
```python
pg = postgres.create_start('main')
conn = pg.connect()
...
conn.close()
```
This pattern can be further improved with the help of `closing`:
```python
from contextlib import closing
pg = postgres.create_start('main')
with closing(pg.connect()) as conn:
...
```
All connections produced by this method will have autocommit
enabled by default.
74 lines
2.7 KiB
Python
74 lines
2.7 KiB
Python
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, postgres, 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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print("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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print('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, 100000) 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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print('LSN after 100100 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, 100000) 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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print('LSN after 200100 rows: ' + lsn_c)
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# Branch at the point where only 200 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() == (100100, )
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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() == (200100, )
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