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e4a279db13
## Problem We are currently supporting two read paths. No bueno. ## Summary of changes High level: use vectored read path to serve get page requests - gated by `get_impl` config Low level: 1. Add ps config, `get_impl` to specify which read path to use when serving get page requests 2. Fix base cached image handling for the vectored read path. This was subtly broken: previously we would not mark keys that went past their cached lsn as complete. This is a self standing change which could be its own PR, but I've included it here because writing separate tests for it is tricky. 3. Fork get page to use either the legacy or vectored implementation 4. Validate the use of vectored read path when serving get page requests against the legacy implementation. Controlled by `validate_vectored_get` ps config. 5. Use the vectored read path to serve get page requests in tests (with validation). ## Note Since the vectored read path does not go through the page cache to read buffers, this change also amounts to a removal of the buffer page cache. Materialized page cache is still used.
210 lines
8.6 KiB
Python
210 lines
8.6 KiB
Python
import re
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import time
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from datetime import datetime, timedelta, timezone
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from fixtures.log_helper import log
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from fixtures.neon_fixtures import NeonEnvBuilder, wait_for_last_flush_lsn
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from fixtures.pageserver.http import PageserverApiException
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from fixtures.types import Lsn
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from fixtures.utils import query_scalar
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#
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# Test pageserver get_lsn_by_timestamp API
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#
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def test_lsn_mapping(neon_env_builder: NeonEnvBuilder):
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env = neon_env_builder.init_start()
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tenant_id, _ = env.neon_cli.create_tenant(
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conf={
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# disable default GC and compaction
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"gc_period": "1000 m",
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"compaction_period": "0 s",
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"gc_horizon": f"{1024 ** 2}",
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"checkpoint_distance": f"{1024 ** 2}",
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"compaction_target_size": f"{1024 ** 2}",
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}
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)
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timeline_id = env.neon_cli.create_branch("test_lsn_mapping", tenant_id=tenant_id)
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endpoint_main = env.endpoints.create_start("test_lsn_mapping", tenant_id=tenant_id)
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timeline_id = endpoint_main.safe_psql("show neon.timeline_id")[0][0]
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cur = endpoint_main.connect().cursor()
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# Obtain an lsn before all write operations on this branch
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start_lsn = Lsn(query_scalar(cur, "SELECT pg_current_wal_lsn()"))
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# Create table, and insert rows, each in a separate transaction
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# Disable synchronous_commit to make this initialization go faster.
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# Disable `synchronous_commit` to make this initialization go faster.
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# XXX: on my laptop this test takes 7s, and setting `synchronous_commit=off`
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# doesn't change anything.
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#
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# Each row contains current insert LSN and the current timestamp, when
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# the row was inserted.
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cur.execute("SET synchronous_commit=off")
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cur.execute("CREATE TABLE foo (x integer)")
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tbl = []
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for i in range(1000):
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cur.execute("INSERT INTO foo VALUES(%s)", (i,))
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# Get the timestamp at UTC
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after_timestamp = query_scalar(cur, "SELECT clock_timestamp()").replace(tzinfo=None)
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tbl.append([i, after_timestamp])
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# Execute one more transaction with synchronous_commit enabled, to flush
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# all the previous transactions
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cur.execute("SET synchronous_commit=on")
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cur.execute("INSERT INTO foo VALUES (-1)")
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# Wait until WAL is received by pageserver
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last_flush_lsn = wait_for_last_flush_lsn(env, endpoint_main, tenant_id, timeline_id)
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with env.pageserver.http_client() as client:
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# Check edge cases
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# Timestamp is in the future
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probe_timestamp = tbl[-1][1] + timedelta(hours=1)
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result = client.timeline_get_lsn_by_timestamp(tenant_id, timeline_id, probe_timestamp)
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assert result["kind"] == "future"
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# make sure that we return a well advanced lsn here
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assert Lsn(result["lsn"]) > start_lsn
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# Timestamp is in the unreachable past
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probe_timestamp = tbl[0][1] - timedelta(hours=10)
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result = client.timeline_get_lsn_by_timestamp(tenant_id, timeline_id, probe_timestamp)
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assert result["kind"] == "past"
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# make sure that we return the minimum lsn here at the start of the range
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assert Lsn(result["lsn"]) < start_lsn
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# Probe a bunch of timestamps in the valid range
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for i in range(1, len(tbl), 100):
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probe_timestamp = tbl[i][1]
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result = client.timeline_get_lsn_by_timestamp(tenant_id, timeline_id, probe_timestamp)
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assert result["kind"] not in ["past", "nodata"]
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lsn = result["lsn"]
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# Call get_lsn_by_timestamp to get the LSN
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# Launch a new read-only node at that LSN, and check that only the rows
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# that were supposed to be committed at that point in time are visible.
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endpoint_here = env.endpoints.create_start(
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branch_name="test_lsn_mapping",
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endpoint_id="ep-lsn_mapping_read",
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lsn=lsn,
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tenant_id=tenant_id,
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)
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assert endpoint_here.safe_psql("SELECT max(x) FROM foo")[0][0] == i
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endpoint_here.stop_and_destroy()
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# Do the "past" check again at a new branch to ensure that we don't return something before the branch cutoff
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timeline_id_child = env.neon_cli.create_branch(
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"test_lsn_mapping_child", tenant_id=tenant_id, ancestor_branch_name="test_lsn_mapping"
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)
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# Timestamp is in the unreachable past
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probe_timestamp = tbl[0][1] - timedelta(hours=10)
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result = client.timeline_get_lsn_by_timestamp(tenant_id, timeline_id_child, probe_timestamp)
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assert result["kind"] == "past"
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# make sure that we return the minimum lsn here at the start of the range
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assert Lsn(result["lsn"]) >= last_flush_lsn
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# Test pageserver get_timestamp_of_lsn API
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def test_ts_of_lsn_api(neon_env_builder: NeonEnvBuilder):
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if neon_env_builder.pageserver_get_impl == "vectored":
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key_not_found_error = r".*Requested key.*not found,*"
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else:
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key_not_found_error = r".*could not find data for key.*"
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env = neon_env_builder.init_start()
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new_timeline_id = env.neon_cli.create_branch("test_ts_of_lsn_api")
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endpoint_main = env.endpoints.create_start("test_ts_of_lsn_api")
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cur = endpoint_main.connect().cursor()
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# Create table, and insert rows, each in a separate transaction
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# Disable synchronous_commit to make this initialization go faster.
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#
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# Each row contains current insert LSN and the current timestamp, when
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# the row was inserted.
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cur.execute("SET synchronous_commit=off")
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cur.execute("CREATE TABLE foo (x integer)")
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tbl = []
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for i in range(1000):
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cur.execute("INSERT INTO foo VALUES(%s)", (i,))
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# Get the timestamp at UTC
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after_timestamp = query_scalar(cur, "SELECT clock_timestamp()").replace(tzinfo=timezone.utc)
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after_lsn = query_scalar(cur, "SELECT pg_current_wal_lsn()")
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tbl.append([i, after_timestamp, after_lsn])
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time.sleep(0.005)
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# Execute one more transaction with synchronous_commit enabled, to flush
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# all the previous transactions
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cur.execute("SET synchronous_commit=on")
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cur.execute("INSERT INTO foo VALUES (-1)")
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# Wait until WAL is received by pageserver
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last_flush_lsn = wait_for_last_flush_lsn(
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env, endpoint_main, env.initial_tenant, new_timeline_id
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)
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with env.pageserver.http_client() as client:
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# Check edge cases: lsn larger than the last flush lsn
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probe_lsn = Lsn(int(last_flush_lsn) * 20 + 80_000)
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result = client.timeline_get_timestamp_of_lsn(
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env.initial_tenant,
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new_timeline_id,
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probe_lsn,
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)
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# lsn of zero
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try:
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probe_lsn = Lsn(0)
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result = client.timeline_get_timestamp_of_lsn(
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env.initial_tenant,
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new_timeline_id,
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probe_lsn,
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)
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# There should always be an error here.
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raise RuntimeError("there should have been an 'Invalid LSN' error")
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except PageserverApiException as error:
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assert error.status_code == 500
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assert str(error) == "Invalid LSN"
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env.pageserver.allowed_errors.append(".*Invalid LSN.*")
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# small lsn before initdb_lsn
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try:
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probe_lsn = Lsn(64)
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result = client.timeline_get_timestamp_of_lsn(
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env.initial_tenant,
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new_timeline_id,
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probe_lsn,
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)
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# There should always be an error here.
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raise RuntimeError("there should have been an 'could not find data for key' error")
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except PageserverApiException as error:
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assert error.status_code == 500
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assert re.match(key_not_found_error, str(error))
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env.pageserver.allowed_errors.append(key_not_found_error)
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# Probe a bunch of timestamps in the valid range
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step_size = 100
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for i in range(step_size, len(tbl), step_size):
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after_timestamp = tbl[i][1]
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after_lsn = tbl[i][2]
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result = client.timeline_get_timestamp_of_lsn(
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env.initial_tenant,
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new_timeline_id,
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after_lsn,
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)
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log.info("result: %s, after_ts: %s", result, after_timestamp)
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# TODO use fromisoformat once we have Python 3.11+
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# which has https://github.com/python/cpython/pull/92177
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timestamp = datetime.strptime(result, "%Y-%m-%dT%H:%M:%S.%f000Z").replace(
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tzinfo=timezone.utc
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)
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assert timestamp < after_timestamp, "after_timestamp after timestamp"
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if i > 1:
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before_timestamp = tbl[i - step_size][1]
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assert timestamp >= before_timestamp, "before_timestamp before timestamp"
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