diff --git a/macros/activity.sql b/macros/activity.sql
index 4a7f45f..9914c3e 100644
--- a/macros/activity.sql
+++ b/macros/activity.sql
@@ -73,7 +73,7 @@ params:
 {# The columns.feature_json requires columns.ts to be present. #}
 {% if (dbt_activity_schema.columns().feature_json in columns) and
     (dbt_activity_schema.columns().ts not in columns) %}
-{% set columns = columns.append(dbt_activity_schema.columns().ts) %}
+{% do columns.append(dbt_activity_schema.columns().ts) %}
 {% endif %}
 
 {% set additional_join_condition = additional_join_condition if additional_join_condition else "true" %}
diff --git a/macros/dataset.sql b/macros/dataset.sql
index 7f43013..79dc5b9 100644
--- a/macros/dataset.sql
+++ b/macros/dataset.sql
@@ -23,10 +23,10 @@ params:
         variables in ./dataclasses/columns.sql to set the columns of the activity
         stream.
 
-    primary_activity: primary_activity (/activities)
+    primary_activity: activity (class)
         The primary activity of the derived dataset.
 
-    appended_activities: List[ appended_activity (/activities) ]
+    appended_activities: List[ activity (class) ]
         The list of appended activities to self-join to the primary activity.
 #}
 
@@ -99,7 +99,7 @@ aggregate_appended_activities as (
         {% for activity in appended_activities %}{% set i = loop.index %}{% set last_outer_loop = loop.last %}
             {% for col in activity.columns %}
 
-        {{ render_agg(activity.relationship.aggregation_func, col, activity) }}
+        {{ render_agg(col, activity) }}
 
         {% if not (last_outer_loop and loop.last) %},{% endif %}
 
diff --git a/macros/relationships/all_ever.sql b/macros/relationships/all_ever.sql
index 4f504a9..c06c6ee 100644
--- a/macros/relationships/all_ever.sql
+++ b/macros/relationships/all_ever.sql
@@ -6,7 +6,7 @@
 
 {% do return(namespace(
     name="all_ever",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.all_ever_join_clause,
     where_clause=dbt_activity_schema.all_ever_join_clause()
 )) %}
diff --git a/macros/relationships/append_only/first_after.sql b/macros/relationships/append_only/first_after.sql
index 49c673d..3c0cfd9 100644
--- a/macros/relationships/append_only/first_after.sql
+++ b/macros/relationships/append_only/first_after.sql
@@ -12,7 +12,7 @@
 
 {% do return(namespace(
     name="first_after",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.first_after_join_clause
 )) %}
 
diff --git a/macros/relationships/append_only/first_before.sql b/macros/relationships/append_only/first_before.sql
index 0c05cdf..c880972 100644
--- a/macros/relationships/append_only/first_before.sql
+++ b/macros/relationships/append_only/first_before.sql
@@ -13,7 +13,7 @@
 
 {% do return(namespace(
     name="first_before",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.first_before_join_clause
 )) %}
 
diff --git a/macros/relationships/append_only/first_in_between.sql b/macros/relationships/append_only/first_in_between.sql
index 9ad6349..d79a519 100644
--- a/macros/relationships/append_only/first_in_between.sql
+++ b/macros/relationships/append_only/first_in_between.sql
@@ -16,7 +16,7 @@
 
 {% do return(namespace(
     name="first_in_between",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.first_in_between_join_clause
 )) %}
 
diff --git a/macros/relationships/append_only/last_after.sql b/macros/relationships/append_only/last_after.sql
index f53ea5c..14d1ca6 100644
--- a/macros/relationships/append_only/last_after.sql
+++ b/macros/relationships/append_only/last_after.sql
@@ -12,7 +12,7 @@
 
 {% do return(namespace(
     name="last_after",
-    aggregation_func="max",
+    aggregation_func=dbt_activity_schema.max,
     join_clause=dbt_activity_schema.last_after_join_clause
 )) %}
 
diff --git a/macros/relationships/append_only/last_before.sql b/macros/relationships/append_only/last_before.sql
index 1c9efbb..1905303 100644
--- a/macros/relationships/append_only/last_before.sql
+++ b/macros/relationships/append_only/last_before.sql
@@ -12,7 +12,7 @@
 
 {% do return(namespace(
     name="last_before",
-    aggregation_func="max",
+    aggregation_func=dbt_activity_schema.max,
     join_clause=dbt_activity_schema.last_before_join_clause
 )) %}
 
diff --git a/macros/relationships/append_only/last_in_between.sql b/macros/relationships/append_only/last_in_between.sql
index 76406e5..174fe3c 100644
--- a/macros/relationships/append_only/last_in_between.sql
+++ b/macros/relationships/append_only/last_in_between.sql
@@ -16,7 +16,7 @@
 
 {% do return(namespace(
     name="last_in_between",
-    aggregation_func="max",
+    aggregation_func=dbt_activity_schema.max,
     join_clause=dbt_activity_schema.last_in_between_join_clause
 )) %}
 
diff --git a/macros/relationships/first_ever.sql b/macros/relationships/first_ever.sql
index c6f29c9..aa043a3 100644
--- a/macros/relationships/first_ever.sql
+++ b/macros/relationships/first_ever.sql
@@ -8,7 +8,7 @@
 
 {% do return(namespace(
     name="first_ever",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.first_ever_join_clause,
     where_clause=dbt_activity_schema.first_ever_join_clause()
 )) %}
diff --git a/macros/relationships/last_ever.sql b/macros/relationships/last_ever.sql
index e5fc14e..655432f 100644
--- a/macros/relationships/last_ever.sql
+++ b/macros/relationships/last_ever.sql
@@ -8,7 +8,7 @@
 
 {% do return(namespace(
     name="last_ever",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     join_clause=dbt_activity_schema.last_ever_join_clause,
     where_clause=dbt_activity_schema.last_ever_join_clause()
 )) %}
diff --git a/macros/relationships/nth_ever.sql b/macros/relationships/nth_ever.sql
index 8da9a26..0f7c3d4 100644
--- a/macros/relationships/nth_ever.sql
+++ b/macros/relationships/nth_ever.sql
@@ -8,7 +8,7 @@
 
 {% do return(namespace(
     name="nth_ever",
-    aggregation_func="min",
+    aggregation_func=dbt_activity_schema.min,
     nth_occurance=nth_occurance,
     join_clause=dbt_activity_schema.nth_ever_join_clause,
     where_clause=dbt_activity_schema.nth_ever_join_clause(nth_occurance)
diff --git a/macros/utils/aggregations/max.sql b/macros/utils/aggregations/max.sql
new file mode 100644
index 0000000..9aec550
--- /dev/null
+++ b/macros/utils/aggregations/max.sql
@@ -0,0 +1,3 @@
+{% macro max() %}
+max({{ caller() }})
+{% endmacro %}
diff --git a/macros/utils/aggregations/min.sql b/macros/utils/aggregations/min.sql
new file mode 100644
index 0000000..5d4e092
--- /dev/null
+++ b/macros/utils/aggregations/min.sql
@@ -0,0 +1,3 @@
+{% macro min() %}
+min({{ caller() }})
+{% endmacro %}
diff --git a/macros/utils/render_aggregation.sql b/macros/utils/render_aggregation.sql
index 066e94c..14ea9e1 100644
--- a/macros/utils/render_aggregation.sql
+++ b/macros/utils/render_aggregation.sql
@@ -1,22 +1,19 @@
-{%- macro render_aggregation(aggregation_func, col, activity) -%}
-	{{ return(adapter.dispatch("render_aggregation", "dbt_activity_schema")(aggregation_func, col, activity)) }}
+{%- macro render_aggregation(col, activity) -%}
+	{{ return(adapter.dispatch("render_aggregation", "dbt_activity_schema")(col, activity)) }}
 {%- endmacro -%}
 
 
-{%- macro default__render_aggregation(aggregation_func, col, activity) -%}
+{%- macro default__render_aggregation(col, activity) -%}
 
 {# Render the aggregation, handling special cases for non-cardinal columns.
 
 params:
 
-    aggregation_func: str
-        A valid SQL aggregation function.
-
     col: str
         The column to aggregate.
 
-    activity: str
-        The activity to aggregate.
+    activity: activity (class)
+        The activity class which contains a name and aggregation function.
 
 #}
 
@@ -28,21 +25,23 @@ params:
 {% if col in [columns.feature_json] %}
 
     {% set ts_concat_feature_json %}
-    (
-        {{ aggregation_func }}(
-            {{ dbt.concat([aliased_activity_ts_col, aliased_col]) }}
-        )
-    )
+        {% call activity.relationship.aggregation_func() %}
+        {{ dbt.concat([aliased_activity_ts_col, aliased_col]) }}
+        {% endcall %}
     {% endset %}
 
     {% set ts_aggregated %}
-    {{ aggregation_func }}({{ aliased_activity_ts_col }})
+        {% call activity.relationship.aggregation_func() %}
+        {{ aliased_activity_ts_col }}
+        {% endcall %}
     {% endset %}
 
     {{ dbt_activity_schema.ltrim(ts_concat_feature_json, ts_aggregated) }} as {{ aliased_col }}
 
 {% else %}
-    {{ aggregation_func }}( {{ aliased_col }} ) as {{ aliased_col }}
+    {% call activity.relationship.aggregation_func() %}
+    {{ aliased_col }}
+    {% endcall %} as {{ aliased_col }}
 {% endif %}
 
 {% endmacro %}