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ae51fef57c
In issue #9083 a user noted that whereas Cassandra's partition-count
estimation is accurate, Scylla's (rewritten in commit b93cc21) is very
inaccurate. The tests introduce here, which all xfail on Scylla, confirm
this suspicion.
The most important tests are the "simple" tests, involving a workload
which writes N *distinct* partitions and then asks for the estimated
partition count. Cassandra provides accurate estimates, which grow
more accurate with more partitions, so it passes these tests, while
Scylla provides bad estimates and fails them.
Additional tests demonstrate that neither Scylla nor Cassandra
can handle anything beyond the "simple" case of distinct partitions.
Two tests which xfail on both Cassandra and Scylla demonstrate that
if we write the same partitions to multiple sstables - or also delete
partitions - the estimated partition counts will be way off.
Refs #9083
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210726211315.1515856-1-nyh@scylladb.com>
81 lines
3.3 KiB
Python
81 lines
3.3 KiB
Python
# Copyright 2021-present ScyllaDB
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#
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# This file is part of Scylla.
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#
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# Scylla is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Scylla is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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##################################################################
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# This file provides a few nodetool-compatible commands that may be useful
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# for tests. The intent is *not* to test nodetool itself, but just to
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# use nodetool functionality - e.g., "nodetool flush" when testing CQL.
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#
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# When testing against a locally-running Scylla these functions do not
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# actually use nodetool but rather Scylla's REST API. This simplifies
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# running the test because an external Java process implementing JMX is
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# not needed. However, when the REST API port is not available (i.e, when
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# testing against Cassandra or some remote installation of Scylla) the
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# external "nodetool" command is used, and must be available in the path or
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# chosen with the NODETOOL environment variable.
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import requests
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import os
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import subprocess
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# For a "cql" object connected to one node, find the REST API URL
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# with the same node and port 10000.
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# TODO: We may need to change this function or its callers to add proper
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# support for testing on multi-node clusters.
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def rest_api_url(cql):
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return f'http://{cql.cluster.contact_points[0]}:10000'
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# Check whether the REST API at port 10000 is available - if not we will
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# fall back to using an external "nodetool" program.
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# We only check this once per REST API URL, and cache the decision.
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checked_rest_api = {}
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def has_rest_api(cql):
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url = rest_api_url(cql)
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if not url in checked_rest_api:
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# Scylla's REST API does not have an official "ping" command,
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# so we just list the keyspaces as a (usually) short operation
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try:
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ok = requests.get(f'{url}/column_family/name/keyspace').ok
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except:
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ok = False
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checked_rest_api[url] = ok
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return checked_rest_api[url]
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# Run the external "nodetool" executable (can be overridden by the NODETOOL
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# environment variable). Only call this if the REST API doesn't work.
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nodetool_cmd = os.getenv('NODETOOL') or 'nodetool'
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def run_nodetool(cql, *args):
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# TODO: We may need to change this function or its callers to add proper
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# support for testing on multi-node clusters.
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host = cql.cluster.contact_points[0]
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subprocess.run([nodetool_cmd, '-h', host, *args])
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def flush(cql, table):
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ks, cf = table.split('.')
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if has_rest_api(cql):
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requests.post(f'{rest_api_url(cql)}/storage_service/keyspace_flush/{ks}', params={'cf' : cf})
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else:
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run_nodetool(cql, "flush", ks, cf)
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def refreshsizeestimates(cql):
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if has_rest_api(cql):
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# The "nodetool refreshsizeestimates" is not available, or needed, in Scylla
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pass
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else:
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run_nodetool(cql, "refreshsizeestimates")
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