Feature/add ignore case option to snowflake

macros/plugins/snowflake/create_external_table.sql

@@ -4,10 +4,11 @@
     {%- set external = source_node.external -%}
     {%- set partitions = external.partitions -%}
     {%- set infer_schema = external.infer_schema -%}
+    {%- set ignore_case = external.ignore_case -%}
 
     {% if infer_schema %}
         {% set query_infer_schema %}
-            select * from table( infer_schema( location=>'{{external.location}}', file_format=>'{{external.file_format}}') )
+            select * from table( infer_schema( location=>'{{external.location}}', file_format=>'{{external.file_format}}'{%- if ignore_case -%}, ignore_case=>{{ignore_case}} {%- endif %} ) )
         {% endset %}
         {% if execute %}
             {% set columns_infer = run_query(query_infer_schema) %}
@@ -50,7 +51,11 @@
         {% else %}
         {%- for column in columns_infer %}
                 {%- set col_expression -%}
-                    {%- set col_id = 'value:' ~ column[0] -%}
+                    {%- if not ignore_case -%}
+                        {%- set col_id = 'value:' ~ column[0] -%}
+                    {%- else -%}
+                        {%- set col_id = "get_ignore_case(value, '{}')".format(column[0]) -%}
+                    {%- endif -%}
                     (case when is_null_value({{col_id}}) or lower({{col_id}}) = 'null' then null else {{col_id}} end)
                 {%- endset %}
                 {{column[0]}} {{column[1]}} as ({{col_expression}}::{{column[1]}})

sample_sources/snowflake.yml

@@ -98,6 +98,23 @@ sources:
           - name: name
             description: and this is a name
 
+      - name: parquet_with_inferred_schema_and_mixed_column_case
+        description: "External table using Parquet and inferring the schema with mixed column case"
+        external:
+          location: "@stage"                  # reference an existing external stage
+          file_format: "my_file_format"       # we need a named file format for infer to work
+          infer_schema: true                  # parameter to tell Snowflake we want to infer the table schema
+          ignore_case: true                   # parameter to tell Snowflake we want to ignore column case differences 
+          partitions:
+            - name: section                   # we can define partitions on top of the schema columns
+              data_type: varchar(64)
+              expression: "substr(split_part(metadata$filename, 'section=', 2), 1, 1)"
+        columns:                              # columns can still be listed for documentation/testing purpose
+          - name: id
+            description: this is an id
+          - name: name
+            description: and this is a name
+
       - name: aws_sns_refresh_tbl
         description: "External table using AWS SNS for auto-refresh"
         external: