neon/test_runner/regress/test_branch_behind.py

import pytest
from fixtures.common_types import Lsn, TimelineId
from fixtures.log_helper import log
from fixtures.neon_fixtures import NeonEnvBuilder
from fixtures.pageserver.http import TimelineCreate406
from fixtures.utils import print_gc_result, query_scalar


#
# Create a couple of branches off the main branch, at a historical point in time.
#
def test_branch_behind(neon_env_builder: NeonEnvBuilder):
    # Disable pitr, because here we want to test branch creation after GC
    neon_env_builder.pageserver_config_override = "tenant_config={pitr_interval = '0 sec'}"
    env = neon_env_builder.init_start()

    error_regexes = [
        ".*invalid branch start lsn.*",
        ".*invalid start lsn .* for ancestor timeline.*",
    ]
    env.pageserver.allowed_errors.extend(error_regexes)
    env.storage_controller.allowed_errors.extend(error_regexes)

    # Branch at the point where only 100 rows were inserted
    branch_behind_timeline_id = env.neon_cli.create_branch("test_branch_behind")
    endpoint_main = env.endpoints.create_start("test_branch_behind")

    main_cur = endpoint_main.connect().cursor()

    timeline = TimelineId(query_scalar(main_cur, "SHOW neon.timeline_id"))

    # Create table, and insert the first 100 rows
    main_cur.execute("CREATE TABLE foo (t text)")

    # keep some early lsn to test branch creation on out of date lsn
    gced_lsn = Lsn(query_scalar(main_cur, "SELECT pg_current_wal_insert_lsn()"))

    main_cur.execute(
        """
        INSERT INTO foo
            SELECT 'long string to consume some space' || g
            FROM generate_series(1, 100) g
    """
    )
    lsn_a = Lsn(query_scalar(main_cur, "SELECT pg_current_wal_insert_lsn()"))
    log.info(f"LSN after 100 rows: {lsn_a}")

    # Insert some more rows. (This generates enough WAL to fill a few segments.)
    main_cur.execute(
        """
        INSERT INTO foo
            SELECT 'long string to consume some space' || g
            FROM generate_series(1, 200000) g
    """
    )
    lsn_b = Lsn(query_scalar(main_cur, "SELECT pg_current_wal_insert_lsn()"))
    log.info(f"LSN after 200100 rows: {lsn_b}")

    # Branch at the point where only 100 rows were inserted
    env.neon_cli.create_branch(
        "test_branch_behind_hundred", "test_branch_behind", ancestor_start_lsn=lsn_a
    )

    # Insert many more rows. This generates enough WAL to fill a few segments.
    main_cur.execute(
        """
        INSERT INTO foo
            SELECT 'long string to consume some space' || g
            FROM generate_series(1, 200000) g
    """
    )
    lsn_c = Lsn(query_scalar(main_cur, "SELECT pg_current_wal_insert_lsn()"))

    log.info(f"LSN after 400100 rows: {lsn_c}")

    # Branch at the point where only 200100 rows were inserted
    env.neon_cli.create_branch(
        "test_branch_behind_more", "test_branch_behind", ancestor_start_lsn=lsn_b
    )

    endpoint_hundred = env.endpoints.create_start("test_branch_behind_hundred")
    endpoint_more = env.endpoints.create_start("test_branch_behind_more")

    # On the 'hundred' branch, we should see only 100 rows
    hundred_cur = endpoint_hundred.connect().cursor()
    assert query_scalar(hundred_cur, "SELECT count(*) FROM foo") == 100

    # On the 'more' branch, we should see 100200 rows
    more_cur = endpoint_more.connect().cursor()
    assert query_scalar(more_cur, "SELECT count(*) FROM foo") == 200100

    # All the rows are visible on the main branch
    assert query_scalar(main_cur, "SELECT count(*) FROM foo") == 400100

    # Check bad lsn's for branching
    pageserver_http = env.pageserver.http_client()

    # branch at segment boundary
    env.neon_cli.create_branch(
        "test_branch_segment_boundary", "test_branch_behind", ancestor_start_lsn=Lsn("0/3000000")
    )
    endpoint = env.endpoints.create_start("test_branch_segment_boundary")
    assert endpoint.safe_psql("SELECT 1")[0][0] == 1

    # branch at pre-initdb lsn (from main branch)
    with pytest.raises(Exception, match="invalid branch start lsn: .*"):
        env.neon_cli.create_branch("test_branch_preinitdb", ancestor_start_lsn=Lsn("0/42"))
    # retry the same with the HTTP API, so that we can inspect the status code
    with pytest.raises(TimelineCreate406):
        new_timeline_id = TimelineId.generate()
        log.info(f"Expecting failure for branch pre-initdb LSN, new_timeline_id={new_timeline_id}")
        pageserver_http.timeline_create(
            env.pg_version, env.initial_tenant, new_timeline_id, env.initial_timeline, Lsn("0/42")
        )

    # branch at pre-ancestor lsn
    with pytest.raises(Exception, match="less than timeline ancestor lsn"):
        env.neon_cli.create_branch(
            "test_branch_preinitdb", "test_branch_behind", ancestor_start_lsn=Lsn("0/42")
        )
    # retry the same with the HTTP API, so that we can inspect the status code
    with pytest.raises(TimelineCreate406):
        new_timeline_id = TimelineId.generate()
        log.info(
            f"Expecting failure for branch pre-ancestor LSN, new_timeline_id={new_timeline_id}"
        )
        pageserver_http.timeline_create(
            env.pg_version,
            env.initial_tenant,
            new_timeline_id,
            branch_behind_timeline_id,
            Lsn("0/42"),
        )

    # check that we cannot create branch based on garbage collected data
    pageserver_http.timeline_checkpoint(env.initial_tenant, timeline)
    gc_result = pageserver_http.timeline_gc(env.initial_tenant, timeline, 0)
    print_gc_result(gc_result)
    with pytest.raises(Exception, match="invalid branch start lsn: .*"):
        # this gced_lsn is pretty random, so if gc is disabled this woudln't fail
        env.neon_cli.create_branch(
            "test_branch_create_fail", "test_branch_behind", ancestor_start_lsn=gced_lsn
        )
    # retry the same with the HTTP API, so that we can inspect the status code
    with pytest.raises(TimelineCreate406):
        new_timeline_id = TimelineId.generate()
        log.info(f"Expecting failure for branch behind gc'd LSN, new_timeline_id={new_timeline_id}")
        pageserver_http.timeline_create(
            env.pg_version, env.initial_tenant, new_timeline_id, branch_behind_timeline_id, gced_lsn
        )

    # check that after gc everything is still there
    assert query_scalar(hundred_cur, "SELECT count(*) FROM foo") == 100

    assert query_scalar(more_cur, "SELECT count(*) FROM foo") == 200100

    assert query_scalar(main_cur, "SELECT count(*) FROM foo") == 400100