Fixed column schemas not being grabbed properly (dremio#282)

### Summary

Fixes the column schema not being properly grabbed from query results

### Description

Previously dbt was not able to get the schema of the columns interacted
with in a query, these changes fix that and we are now able to get
information about the columns (names and data types)

### Test Results

3 expected failures fixed
2 skipped tests that were also failing are not skipped anymore

### Changelog

-   [x] Added a summary of what this PR accomplishes to CHANGELOG.md

### Contributor License Agreement

- [x] Please make sure you have signed our [Contributor License
Agreement](https://www.dremio.com/legal/contributor-agreement/), which
enables Dremio to distribute your contribution without restriction.

### Related Issue

Fixes dremio#20 and also some other tests

Author: bcmeireles

.github/expected_failures.txt

@@ -1,15 +1,12 @@
 tests/component/test_profile_template.py::TestProfileTemplate::test_cloud_options
-tests/functional/adapter/dbt_clone/test_dbt_clone.py::TestCloneNotPossibleDremio::test_can_clone_false
 tests/functional/adapter/dremio_specific/test_drop_temp_table.py::TestDropTempTableDremio::test_drop_temp_table
 tests/functional/adapter/dremio_specific/test_schema_parsing.py::TestSchemaParsingDremio::test_schema_with_dots
 tests/functional/adapter/dremio_specific/test_verify_ssl.py::TestVerifyCertificateDremio::test_insecure_request_warning_not_exist
 tests/functional/adapter/unit_testing/test_unit_testing.py::TestDremioUnitTestingTypes::test_unit_test_data_type
 tests/functional/adapter/unit_testing/test_unit_testing.py::TestDremioUnitTestCaseInsensitivity::test_case_insensitivity
 tests/functional/adapter/unit_testing/test_unit_testing.py::TestDremioUnitTestInvalidInput::test_invalid_input
-tests/hooks/test_model_hooks.py::TestPrePostModelHooksOnSnapshotsDremio::test_hooks_on_snapshots
 tests/hooks/test_model_hooks.py::TestPrePostModelHooksInConfigDremio::test_pre_and_post_model_hooks_model
 tests/hooks/test_model_hooks.py::TestPrePostModelHooksInConfigWithCountDremio::test_pre_and_post_model_hooks_model_and_project
 tests/hooks/test_model_hooks.py::TestPrePostModelHooksInConfigKwargsDremio::test_pre_and_post_model_hooks_model
-tests/hooks/test_model_hooks.py::TestPrePostSnapshotHooksInConfigKwargsDremio::test_hooks_on_snapshots
 tests/hooks/test_run_hooks.py::TestPrePostRunHooksDremio::test_pre_and_post_run_hooks
 tests/hooks/test_run_hooks.py::TestPrePostRunHooksDremio::test_pre_and_post_seed_hooks

CHANGELOG.md

@@ -8,10 +8,13 @@
 - Adds `BaseIncrementalOnSchemaChange` test to test_incremental.py
 - Changed logic for partitioning when materializing tables. Double quoting issue has been removed, now letting the user decide the quoting
     - New example: `partition_by=['month("datetime_utc")']`
+- Fixed a bug with grabbing the column schemas from queries (names and data types)
+    - Invisible to the users but it was the cause for some other bugs users were facing that have now been fixed
 ## Features
 
 - [#259](https://github.com/dremio/dbt-dremio/pull/259) Added support for roles in grants
 - [#273](https://github.com/dremio/dbt-dremio/pull/273) Fix issue with on_schema_change config
+- [#282](https://github.com/dremio/dbt-dremio/pull/282) Fix issue with get_column_schema_from_query
 
 # dbt-dremio v1.8.1
 

dbt/adapters/dremio/__init__.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from dbt.adapters.dremio.column import DremioColumn
 from dbt.adapters.dremio.connections import DremioConnectionManager
 from dbt.adapters.dremio.credentials import DremioCredentials
 from dbt.adapters.dremio.impl import DremioAdapter

dbt/adapters/dremio/column.py

@@ -0,0 +1,10 @@
+from dataclasses import dataclass
+
+from dbt.adapters.base.column import Column
+
+@dataclass(init=False)
+class DremioColumn(Column):
+    TYPE_LABELS = {
+        "TEXT": "VARCHAR",
+        "STRING": "VARCHAR",
+    }

dbt/adapters/dremio/connections.py

@@ -174,6 +174,10 @@ def get_response(cls, cursor: DremioCursor) -> AdapterResponse:
         message = "OK" if rows == -1 else str(rows)
         return AdapterResponse(_message=message, rows_affected=rows)
 
+    @classmethod
+    def data_type_code_to_name(cls, type_code) -> str:
+        return type_code
+
     def execute(
             self,
             sql: str,

dbt/adapters/dremio/impl.py

@@ -15,11 +15,13 @@
 import agate
 from dbt.adapters.sql import SQLAdapter
 from dbt.adapters.dremio import DremioConnectionManager
+from dbt.adapters.dremio.column import DremioColumn
 from dbt.adapters.dremio.relation import DremioRelation
 from typing import Dict
 
 from typing import List
 from typing import Optional
+from dbt.adapters.base.column import Column as BaseColumn
 from dbt.adapters.base.meta import available
 from dbt.adapters.base.relation import BaseRelation
 
@@ -38,6 +40,7 @@
 class DremioAdapter(SQLAdapter):
     ConnectionManager = DremioConnectionManager
     Relation = DremioRelation
+    Column = DremioColumn
 
     _capabilities = CapabilityDict(
         {
@@ -157,6 +160,17 @@ def standardize_grants_dict(self, grants_table: agate.Table) -> dict:
                 grants_dict.update({privilege: [f"{grantee_type}:{grantee}"]})
         return grants_dict
 
+    def get_column_schema_from_query(self, sql: str) -> List[BaseColumn]:
+        """Get a list of the Columns with names and data types from the given sql."""
+        _, cursor = self.connections.add_select_query(sql)
+        columns = [
+            self.Column.create(
+                entry['name'], self.connections.data_type_code_to_name(entry['type']['name'])
+            )
+            for entry in cursor.job_results()['schema']
+        ]
+        return columns
+
     # This is for use in the test suite
     # Need to override to add fetch to the execute method
     def run_sql_for_tests(self, sql, fetch, conn):

dbt/include/dremio/macros/adapters/columns.sql

@@ -118,3 +118,13 @@ limitations under the License.*/
   {{ return(result) }}
 
 {% endmacro %}
+
+{% macro dremio__get_empty_subquery_sql(select_sql, select_sql_header=none) %}
+    {%- if select_sql_header is not none -%}
+    {{ select_sql_header }}
+    {%- endif -%}
+    select * from (
+        {{ select_sql }}
+    ) as __dbt_sbq
+    limit 1
+{% endmacro %}

tests/functional/adapter/basic/test_snapshots.py

@@ -22,7 +22,6 @@
 from tests.utils.util import BUCKET
 
 
-@pytest.mark.skip(reason="https://github.com/dremio/dbt-dremio/issues/20")
 class TestSnapshotCheckColsDremio(BaseSnapshotCheckCols):
     @pytest.fixture(scope="class")
     def unique_schema(self, request, prefix) -> str:
@@ -61,7 +60,6 @@ def project_config_update(self):
             "name": "snapshot_strategy_check_cols",
         }
 
-@pytest.mark.skip(reason="https://github.com/dremio/dbt-dremio/issues/20")
 class TestSnapshotTimestampDremio(BaseSnapshotTimestamp):
     @pytest.fixture(scope="class")
     def unique_schema(self, request, prefix) -> str: