7181a6757a
This patch adds two tests for two interesting edge cases in the behavior of static columns in Scylla. We already have a lot of tests for static columns in other frameworks (C++ unit tests, cql and dtest), but the two cases here are issues where specifically we weren't sure how Cassandra behaves in those cases - and this can most easily be checked in the test/cql-pytest framework. The first test, test_static_not_selected, is a reproducer for issue #10091. This issue was reported by a user @aohotnik, who was surprised by the fact that Scylla returns empty values, instead of nothing, when selecting regular columns of a non-existent row if the partition has a static column set. The test demonstrates a difference between Scylla and Cassandra, so it is marked "xfail" - it passes on Cassandra and fails on Scylla. If later we decide that both Scylla's and Cassandra's behaviours are reasonable and both can be considered "correct", we can change this test to except Scylla's result as well and it will beging to pass. The second test, test_missing_row_with_static, shows that SELECT of a non-existent row returns nothing - even if the partition has a static column. The behavior in this case is identical in Scylla and Cassandra, so this test passes. This contrasts with the analogous situation in LWT UPDATE from issue #10081, where the IF condition is expected to see the static column value. Refs #10081 Refs #10091 Signed-off-by: Nadav Har'El <nyh@scylladb.com> Message-Id: <20220220120418.831540-1-nyh@scylladb.com>
67 lines
3.4 KiB
Python
67 lines
3.4 KiB
Python
# Copyright 2022-present ScyllaDB
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#
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# SPDX-License-Identifier: AGPL-3.0-or-later
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#############################################################################
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# Various tests for static-column support in Scylla.
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# Note that we have many more tests for static columns in other test
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# frameworks (C++, cql, dtest) but the benefit of these tests is that they
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# allow running tests with debatable behavior on Cassandra as well.
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#############################################################################
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import pytest
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from util import new_test_table, unique_key_int
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@pytest.fixture(scope="module")
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def table1(cql, test_keyspace):
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schema='p int, c int, r int, s int static, PRIMARY KEY(p, c)'
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with new_test_table(cql, test_keyspace, schema) as table:
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yield table
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# Test what happens when we SELECT a partition which has a static column
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# set but no clustering row, but the static column is *not* selected.
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# Reproduces issue #10091.
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#
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# Marking this issue "xfail" because Scylla and Cassandra differ in behavior
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# and we have no good explanation why Scylla's behavior is more correct than
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# Cassandra. If we later decide that we consider *both* behaviors equally
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# correct, we can change the test to accept both and make it pass.
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@pytest.mark.xfail(reason="issue #10091")
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def test_static_not_selected(cql, table1):
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p = unique_key_int()
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# The partition p doesn't exist, so the following select yields nothing:
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assert list(cql.execute(f'SELECT * FROM {table1} WHERE p={p}')) == []
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# Insert just the static column, and no clustering row:
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cql.execute(f'INSERT INTO {table1} (p, s) values ({p}, 1)')
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# If we select all the columns, including the static column s, SELECTing
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# the partition gives us one "row" with the static column set and all
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# other columns set to null - otherwise the static column cannot be
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# returned.
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assert list(cql.execute(f'SELECT * FROM {table1} WHERE p={p}')) == [(p,None,1,None)]
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# But what happens if we SELECT just regular (non-static) columns?
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# Should the SELECT return nothing (since there is no clustering row),
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# or return one "row" with null columns (basically just like in the
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# previous SELECT, just intersected with the desired column)?
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# Currently, Cassandra does the former, Scylla does the latter,
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# so the following assert fails on Scylla:
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assert list(cql.execute(f'SELECT r FROM {table1} WHERE p={p}')) == []
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# Verify that if a partition has a static column set, reading an *existing*
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# clustering row will return it, but reading a *non-existing* row will not
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# return anything - not even the static column.
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#
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# Contrast this with issue #10081 (test_lwt.py::test_lwt_missing_row_with_static)
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# where we suggested that in an UPDATE with IF condition (LWT), the static
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# columns should be readable in the condition expression, whether or not the
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# given row exists.
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def test_missing_row_with_static(cql, table1):
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p = unique_key_int()
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# Insert into partition p just static column and once clustering row c=2
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cql.execute(f'INSERT INTO {table1}(p, s, c, r) values ({p}, 1, 2, 3)')
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# If we SELECT row c=2, we get it and the static column:
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assert list(cql.execute(f'SELECT p, s, c, r FROM {table1} WHERE p={p} AND c=2')) == [(p, 1, 2, 3)]
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# If we SELECT row c=1 (which doesn't exist), we get nothing - not even
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# the static column
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assert list(cql.execute(f'SELECT p, s, c, r FROM {table1} WHERE p={p} AND c=1')) == []
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