Add Incremental Merge Strategy (#228)

### Summary

Add implementation for merge functionality when using an incremental
materialization.

### Description

Dremio supports both merge and append now. More details on how to use
merge strategies can be found here:
https://docs.getdbt.com/docs/build/incremental-strategy#strategy-specific-configs.

### Test Results

Only ran incremental tests as the new changes don't impact other parts
of the adapter.

### Changelog

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

### Related Issue
(#224)

CHANGELOG.md

@@ -1,12 +1,15 @@
+# dbt-dremio MAIN
+
+-   [#223](https://github.com/dremio/dbt-dremio/issues/224) Implement merge strategy for incremental materializations
+
 # dbt-dremio v1.7.0
 
 ## Changes
--   [#8307](https://github.com/dbt-labs/dbt-core/discussions/8307) Allow source freshness to be evaluated from table metadata
--   [#8307](https://github.com/dbt-labs/dbt-core/discussions/8307) Catalog fetch performance improvements
--   [#8307](https://github.com/dbt-labs/dbt-core/discussions/8307) Migrate data_spine macros
--   [#195](https://github.com/dremio/dbt-dremio/issues/195) Ensure api call to create folders does not get called when creating a table
+
+-   [#195](https://github.com/dremio/dbt-dremio/issues/195) Ensure the adapter does not try and create folders in object storage source
 -   [#220](https://github.com/dremio/dbt-dremio/pull/220) Optimize networking performance with Dremio server
 
+
 # dbt-dremio v1.5.1
 
 ## Changes

dbt/include/dremio/macros/materializations/incremental/incremental.sql

@@ -61,16 +61,17 @@ limitations under the License.*/
     -- Process schema changes. Returns dict of changes if successful. Use source columns for upserting/merging
     {% set dest_columns = process_schema_changes(on_schema_change, temp_relation, existing_relation) %}
     {% if not dest_columns %}
-      {% set dest_columns = adapter.get_columns_in_relation(existing_relation) %}
+      {% set dest_columns = dremio__get_columns_in_relation(existing_relation) %}
     {% endif %}
 
     -- Get the incremental_strategy, the macro to use for the strategy, and build the sql
     {%- set incremental_strategy = config.get('incremental_strategy', validator=validation.any[basestring]) or 'append' -%}
     {%- set raw_file_format = config.get('format', validator=validation.any[basestring]) or 'iceberg' -%}
     {%- set file_format = dbt_dremio_validate_get_file_format(raw_file_format) -%}
-    {%- set strategy = dbt_dremio_validate_get_incremental_strategy(incremental_strategy, file_format) -%}
+    {%- set incremental_predicates = config.get('predicates', none) or config.get('incremental_predicates', none) -%}
+    {%- set strategy = dbt_dremio_validate_get_incremental_strategy(incremental_strategy) -%}
     {%- set raw_on_schema_change = config.get('on_schema_change', validator=validation.any[basestring]) or 'ignore' -%}
-    {% set build_sql = dbt_dremio_get_incremental_sql(strategy, intermediate_relation, target_relation, unique_key) %}
+    {% set build_sql = dbt_dremio_get_incremental_sql(strategy, intermediate_relation, target_relation, dest_columns, unique_key) %}
 
   {% endif %}
 

dbt/include/dremio/macros/materializations/incremental/strategies.sql

@@ -12,26 +12,71 @@ 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.*/
 
-{% macro get_insert_into_sql(source_relation, target_relation) %}
 
-    {%- set dest_columns = adapter.get_columns_in_relation(target_relation) -%}
-    {%- set src_columns = adapter.get_columns_in_relation(source_relation) -%}
-    {%- set intersection = intersect_columns(src_columns, dest_columns) -%}
-    {%- set dest_cols_csv = intersection | map(attribute='quoted') | join(', ') -%}
+{% macro dremio__get_incremental_append_sql(source_relation, target_relation, dest_columns) %}
+    {%- set dest_cols_csv = dest_columns | map(attribute='quoted') | join(', ') -%}
     insert into {{ target_relation }}( {{dest_cols_csv}} )
     select {{dest_cols_csv}} from {{ source_relation }}
 
 {% endmacro %}
 
-{% macro dbt_dremio_get_incremental_sql(strategy, source, target, unique_key) %}
+
+{% macro dremio__get_incremental_merge_sql(target, source, unique_key, dest_columns, incremental_predicates=none) -%}
+ {%- set predicates = [] if incremental_predicates is none else [] + incremental_predicates -%}
+    {%- set dest_cols_csv = get_quoted_csv(dest_columns | map(attribute="name")) -%}
+    {%- set merge_update_columns = config.get('merge_update_columns') -%}
+    {%- set merge_exclude_columns = config.get('merge_exclude_columns') -%}
+    {%- set update_columns = get_merge_update_columns(merge_update_columns, merge_exclude_columns, dest_columns) -%}
+    {%- set sql_header = config.get('sql_header', none) -%}
+
+    {% if unique_key %}
+        {% if unique_key is sequence and unique_key is not mapping and unique_key is not string %}
+            {% for key in unique_key %}
+                {% set this_key_match %}
+                    DBT_INTERNAL_SOURCE.{{ key }} = DBT_INTERNAL_DEST.{{ key }}
+                {% endset %}
+                {% do predicates.append(this_key_match) %}
+            {% endfor %}
+        {% else %}
+            {% set unique_key_match %}
+                DBT_INTERNAL_SOURCE.{{ unique_key }} = DBT_INTERNAL_DEST.{{ unique_key }}
+            {% endset %}
+            {% do predicates.append(unique_key_match) %}
+        {% endif %}
+    {% else %}
+        {% do predicates.append('FALSE') %}
+    {% endif %}
+
+    {{ sql_header if sql_header is not none }}
+
+    merge into {{ target }} as DBT_INTERNAL_DEST
+        using {{ source }} as DBT_INTERNAL_SOURCE
+        on {{"(" ~ predicates | join(") and (") ~ ")"}}
+
+    {% if unique_key %}
+    when matched then update set
+        {% for column_name in update_columns -%}
+            {{ column_name }} = DBT_INTERNAL_SOURCE.{{ column_name }}
+            {%- if not loop.last %}, {%- endif %}
+        {%- endfor %}
+    {% endif %}
+
+    when not matched then insert
+        ({{ dest_cols_csv }})
+    values
+        ({{ dest_cols_csv }})
+
+{% endmacro %}
+
+{% macro dbt_dremio_get_incremental_sql(strategy, source, target, dest_columns, unique_key) %}
   {%- if strategy == 'append' -%}
-    {#-- insert new records into existing table, without updating or overwriting #}
-    {{ get_insert_into_sql(source, target) }}
+    {{ dremio__get_incremental_append_sql(source, target, dest_columns) }}
+  {%- elif strategy == 'merge' -%}
+    {{dremio__get_incremental_merge_sql(target, source, unique_key, dest_columns, incremental_predicates=none)}} 
   {%- else -%}
     {% set no_sql_for_strategy_msg -%}
       No known SQL for the incremental strategy provided: {{ strategy }}
     {%- endset %}
     {%- do exceptions.CompilationError(no_sql_for_strategy_msg) -%}
   {%- endif -%}
-
 {% endmacro %}

dbt/include/dremio/macros/materializations/incremental/validate.sql

@@ -29,15 +29,15 @@ limitations under the License.*/
   {% do return(raw_file_format) %}
 {% endmacro %}
 
-{% macro dbt_dremio_validate_get_incremental_strategy(raw_strategy, file_format) %}
+{% macro dbt_dremio_validate_get_incremental_strategy(raw_strategy) %}
   {#-- Validate the incremental strategy #}
 
   {% set invalid_strategy_msg -%}
     Invalid incremental strategy provided: {{ raw_strategy }}
-    Expected one of: 'append'
+    Expected one of: 'append, merge'
   {%- endset %}
 
-  {% if raw_strategy not in ['append'] %}
+  {% if raw_strategy not in ['append', 'merge'] %}
     {% do exceptions.CompilationError(invalid_strategy_msg) %}
   {% endif %}
 

tests/functional/adapter/basic/test_incremental.py

@@ -17,8 +17,54 @@
     BaseIncremental,
     BaseIncrementalNotSchemaChange,
 )
-from dbt.tests.util import run_dbt, check_relations_equal, relation_from_name
+from dbt.tests.adapter.incremental.test_incremental_merge_exclude_columns import (
+    BaseMergeExcludeColumns,
+)
 from tests.fixtures.profiles import unique_schema, dbt_profile_data
+from tests.utils.util import BUCKET, SOURCE
+from dbt.tests.util import run_dbt, relation_from_name, check_relations_equal
+from collections import namedtuple
+
+
+models__merge_exclude_columns_sql = """
+{{ config(
+    materialized = 'incremental',
+    unique_key = 'id',
+    incremental_strategy='merge',
+    merge_exclude_columns='msg'
+) }}
+
+{% if not is_incremental() %}
+
+-- data for first invocation of model
+
+select 1 as id, 'hello' as msg, 'blue' as color
+union all
+select 2 as id, 'goodbye' as msg, 'red' as color
+
+{% else %}
+
+-- data for subsequent incremental update
+
+select 1 as id, 'hey' as msg, 'blue' as color
+union all
+select 2 as id, 'yo' as msg, 'green' as color
+union all
+select 3 as id, 'anyway' as msg, 'purple' as color
+
+{% endif %}
+"""
+
+ResultHolder = namedtuple(
+    "ResultHolder",
+    [
+        "seed_count",
+        "model_count",
+        "seed_rows",
+        "inc_test_model_count",
+        "relation",
+    ],
+)
 
 
 # Need to modify test to not assert any sources for it to pass
@@ -65,3 +111,29 @@ def test_incremental(self, project):
 
 class TestBaseIncrementalNotSchemaChange(BaseIncrementalNotSchemaChange):
     pass
+
+
+class TestBaseMergeExcludeColumnsDremio(BaseMergeExcludeColumns):
+    def get_test_fields(self, project, seed, incremental_model, update_sql_file):
+        seed_count = len(run_dbt(["seed", "--select", seed, "--full-refresh"]))
+
+        model_count = len(
+            run_dbt(["run", "--select", incremental_model, "--full-refresh"])
+        )
+
+        relation = incremental_model
+        # update seed in anticipation of incremental model update
+        row_count_query = "select * from {}.{}".format(
+            f"{SOURCE}.{BUCKET}.{project.test_schema}", seed
+        )
+
+        seed_rows = len(project.run_sql(row_count_query, fetch="all"))
+
+        # propagate seed state to incremental model according to unique keys
+        inc_test_model_count = self.update_incremental_model(
+            incremental_model=incremental_model
+        )
+
+        return ResultHolder(
+            seed_count, model_count, seed_rows, inc_test_model_count, relation
+        )