Issue #127 - Respect SQL Servers Parameter Limit

CHANGELOG.md

@@ -1,4 +1,15 @@
 # Changelog
+
+### v0.20.0
+
+#### features
+
+- users can now declare a custom `max_batch_size` in the project configuration to set the batch size used by the seed file loader. [#127](https://github.com/dbt-msft/dbt-sqlserver/issues/127) and [#151](https://github.com/dbt-msft/dbt-sqlserver/pull/151) thanks [@jacobm001](https://github.com/jacobm001)
+
+#### under the hood
+
+- `sqlserver__load_csv_rows` now has a safety provided by `calc_batch_size()` to ensure the insert statements won't exceed SQL Server's 2100 parameter limit. [#127](https://github.com/dbt-msft/dbt-sqlserver/issues/127) and [#151](https://github.com/dbt-msft/dbt-sqlserver/pull/151) thanks [@jacobm001](https://github.com/jacobm001)
+
 ### v0.19.2
 
 #### fixes

README.md

@@ -137,6 +137,15 @@ client_secret: clientsecret
 
 ### Seeds
 
+By default, dbt-sqlserver will attempt to insert seed files in batches of 400 rows. If this exceeds SQL Server's 2100 parameter limit, the adapter will automatically limit to the highest safe value possible.
+
+To set a different default seed value, you can set the variable `max_batch_size` in your project configuration.
+
+```yaml
+vars:
+  max_batch_size: 200 # Any integer less than  or equal to 2100 will do.
+```
+
 ### Hooks
 
 ### Custom schemas

dbt/include/sqlserver/macros/materializations/seed/seed.sql

@@ -1,7 +1,23 @@
-{% macro sqlserver__basic_load_csv_rows(model, batch_size, agate_table) %}
+{% macro calc_batch_size(num_columns,max_batch_size) %}
+    {#
+        SQL Server allows for a max of 2100 parameters in a single statement.
+        Check if the max_batch_size fits with the number of columns, otherwise
+        reduce the batch size so it fits.
+    #}
+    {% if num_columns * max_batch_size < 2100 %}
+    {% set batch_size = max_batch_size %}
+    {% else %}
+    {% set batch_size = (2100 / num_columns)|int %}
+    {% endif %}
+
+    {{ return(batch_size) }}
+{%  endmacro %}
+
+{% macro sqlserver__basic_load_csv_rows(model, max_batch_size, agate_table) %}
     {% set cols_sql = get_seed_column_quoted_csv(model, agate_table.column_names) %}
-    {% set bindings = [] %}
 
+    {% set batch_size = calc_batch_size(cols_sql|length, max_batch_size) %}
+    {% set bindings = [] %}
     {% set statements = [] %}
 
     {% for chunk in agate_table.rows | batch(batch_size) %}
@@ -34,5 +50,6 @@
 {% endmacro %}
 
 {% macro sqlserver__load_csv_rows(model, agate_table) %}
-  {{ return(sqlserver__basic_load_csv_rows(model, 200, agate_table) )}}
+  {% set max_batch_size = var("max_batch_size", 400) %}
+  {{ return(sqlserver__basic_load_csv_rows(model, max_batch_size, agate_table) )}}
 {% endmacro %}