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superset2/tests/unit_tests/db_engine_specs/test_redshift.py
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# Licensed to the Apache Software Foundation (ASF) under one
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# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
from datetime import datetime
from typing import Optional
import pytest
from superset.db_engine_specs.redshift import RedshiftEngineSpec
from tests.unit_tests.db_engine_specs.utils import assert_convert_dttm
from tests.unit_tests.fixtures.common import dttm # noqa: F401
@pytest.mark.parametrize(
"target_type,expected_result",
[
("Date", "TO_DATE('2019-01-02', 'YYYY-MM-DD')"),
(
"DateTime",
"TO_TIMESTAMP('2019-01-02 03:04:05.678900', 'YYYY-MM-DD HH24:MI:SS.US')",
),
(
"TimeStamp",
"TO_TIMESTAMP('2019-01-02 03:04:05.678900', 'YYYY-MM-DD HH24:MI:SS.US')",
),
("UnknownType", None),
],
)
def test_convert_dttm(
target_type: str,
expected_result: Optional[str],
dttm: datetime, # noqa: F811
) -> None:
from superset.db_engine_specs.redshift import (
RedshiftEngineSpec as spec, # noqa: N813
)
assert_convert_dttm(spec, target_type, expected_result, dttm)
@pytest.mark.parametrize(
"table_name,schema_name,expected_table,expected_schema",
[
("BPO_mytest_2", "MySchema", "bpo_mytest_2", "myschema"),
("MY_TABLE", None, "my_table", None),
("already_lower", "lower_schema", "already_lower", "lower_schema"),
],
)
def test_normalize_table_name_for_upload(
table_name: str,
schema_name: Optional[str],
expected_table: str,
expected_schema: Optional[str],
) -> None:
"""
Test that table and schema names are normalized to lowercase for Redshift.
Redshift folds unquoted identifiers to lowercase, so we need to normalize
table names to ensure consistent behavior when checking table existence
and performing replace operations.
"""
normalized_table, normalized_schema = (
RedshiftEngineSpec.normalize_table_name_for_upload(table_name, schema_name)
)
assert normalized_table == expected_table
assert normalized_schema == expected_schema
def test_extended_aggregation_func_inherited_from_postgres() -> None:
"""
Redshift is a Postgres fork and inherits STDDEV_SAMP/VAR_SAMP from
`PostgresBaseEngineSpec` -- its documented SQL function reference matches
Postgres for these functions, though this has not been separately
verified against a live Redshift instance (see the SIP doc for caveats).
MEDIAN is overridden rather than inherited (see
`RedshiftEngineSpec._extended_aggregations`): unlike Postgres, Redshift
documents a native `MEDIAN(x)` function, so Redshift emits that directly
instead of Postgres's `percentile_cont(0.5) WITHIN GROUP (ORDER BY col)`
spelling -- which also sidesteps Redshift's documented restriction
against more than one sort-based aggregate with a different ORDER BY in
the same query, e.g. `MEDIAN(sales)` alongside `MEDIAN(margin)`.
"""
from sqlalchemy import column
col = column("sales")
median_func = RedshiftEngineSpec.get_extended_aggregation_func("MEDIAN")
assert median_func is not None
assert (
str(median_func(col).compile(compile_kwargs={"literal_binds": True}))
== "median(sales)"
)
for aggregate in ("STDDEV_SAMP", "VAR_SAMP"):
assert RedshiftEngineSpec.get_extended_aggregation_func(aggregate) is not None