Fix for re-used check cols in snapshots

core/dbt/include/global_project/macros/materializations/snapshot/snapshot.sql

@@ -31,6 +31,15 @@
 
     ),
 
+    snapshotted_data as (
+
+        select *,
+            {{ strategy.unique_key }} as dbt_unique_key
+
+        from {{ target_relation }}
+
+    ),
+
     source_data as (
 
         select *,
@@ -43,15 +52,6 @@
         from snapshot_query
     ),
 
-    snapshotted_data as (
-
-        select *,
-            {{ strategy.unique_key }} as dbt_unique_key
-
-        from {{ target_relation }}
-
-    ),
-
     insertions as (
 
         select
@@ -84,6 +84,15 @@
 
     ),
 
+    snapshotted_data as (
+
+        select *,
+            {{ strategy.unique_key }} as dbt_unique_key
+
+        from {{ target_relation }}
+
+    ),
+
     source_data as (
 
         select
@@ -96,15 +105,6 @@
         from snapshot_query
     ),
 
-    snapshotted_data as (
-
-        select *,
-            {{ strategy.unique_key }} as dbt_unique_key
-
-        from {{ target_relation }}
-
-    ),
-
     updates as (
 
         select
@@ -202,7 +202,7 @@
   {%- endif -%}
 
   {% set strategy_macro = strategy_dispatch(strategy_name) %}
-  {% set strategy = strategy_macro(model, "snapshotted_data", "source_data", config) %}
+  {% set strategy = strategy_macro(model, "snapshotted_data", "source_data", config, target_relation_exists) %}
 
   {% if not target_relation_exists %}
 

core/dbt/include/global_project/macros/materializations/snapshot/strategies.sql

@@ -35,16 +35,17 @@
 {#
     Create SCD Hash SQL fields cross-db
 #}
-{% macro snapshot_hash_arguments(args) %}
+{% macro snapshot_hash_arguments(args) -%}
   {{ adapter_macro('snapshot_hash_arguments', args) }}
-{% endmacro %}
+{%- endmacro %}
 
 
-{% macro default__snapshot_hash_arguments(args) %}
+{% macro default__snapshot_hash_arguments(args) -%}
     md5({% for arg in args %}
-        coalesce(cast({{ arg }} as varchar ), '') {% if not loop.last %} || '|' || {% endif %}
+        coalesce(cast({{ arg }} as varchar ), '')
+        {% if not loop.last %} || '|' || {% endif %}
     {% endfor %})
-{% endmacro %}
+{%- endmacro %}
 
 
 {#
@@ -62,7 +63,7 @@
 {#
     Core strategy definitions
 #}
-{% macro snapshot_timestamp_strategy(node, snapshotted_rel, current_rel, config) %}
+{% macro snapshot_timestamp_strategy(node, snapshotted_rel, current_rel, config, target_exists) %}
     {% set primary_key = config['unique_key'] %}
     {% set updated_at = config['updated_at'] %}
 
@@ -81,7 +82,7 @@
 {% endmacro %}
 
 
-{% macro snapshot_check_strategy(node, snapshotted_rel, current_rel, config) %}
+{% macro snapshot_check_strategy(node, snapshotted_rel, current_rel, config, target_exists) %}
     {% set check_cols_config = config['check_cols'] %}
     {% set primary_key = config['unique_key'] %}
     {% set updated_at = snapshot_get_time() %}
@@ -106,7 +107,18 @@
         )
     {%- endset %}
 
-    {% set scd_id_cols = [primary_key] + (check_cols | list) %}
+    {% if target_exists %}
+        {% set row_version -%}
+            (
+             select count(*) from {{ snapshotted_rel }}
+             where {{ snapshotted_rel }}.dbt_unique_key = {{ primary_key }}
+            )
+        {%- endset %}
+        {% set scd_id_cols = [primary_key, row_version] + (check_cols | list) %}
+    {% else %}
+        {% set scd_id_cols = [primary_key] + (check_cols | list) %}
+    {% endif %}
+
     {% set scd_id_expr = snapshot_hash_arguments(scd_id_cols) %}
 
     {% do return({

plugins/bigquery/dbt/adapters/bigquery/connections.py

@@ -202,15 +202,31 @@ def raw_execute(self, sql, fetch=False):
 
     def execute(self, sql, auto_begin=False, fetch=None):
         # auto_begin is ignored on bigquery, and only included for consistency
-        _, iterator = self.raw_execute(sql, fetch=fetch)
+        query_job, iterator = self.raw_execute(sql, fetch=fetch)
 
         if fetch:
             res = self.get_table_from_response(iterator)
         else:
             res = dbt.clients.agate_helper.empty_table()
 
-        # If we get here, the query succeeded
-        status = 'OK'
+        if query_job.statement_type == 'CREATE_VIEW':
+            status = 'CREATE VIEW'
+
+        elif query_job.statement_type == 'CREATE_TABLE_AS_SELECT':
+            conn = self.get_thread_connection()
+            client = conn.handle
+            table = client.get_table(query_job.destination)
+            status = 'CREATE TABLE ({})'.format(table.num_rows)
+
+        elif query_job.statement_type in ['INSERT', 'DELETE', 'MERGE']:
+            status = '{} ({})'.format(
+                query_job.statement_type,
+                query_job.num_dml_affected_rows
+            )
+
+        else:
+            status = 'OK'
+
         return status, res
 
     def create_bigquery_table(self, database, schema, table_name, callback,

plugins/bigquery/dbt/include/bigquery/macros/materializations/snapshot.sql

@@ -1,6 +1,9 @@
-{% macro bigquery__snapshot_hash_arguments(args) %}
-  to_hex(md5(concat({% for arg in args %}coalesce(cast({{ arg }} as string), ''){% if not loop.last %}, '|',{% endif %}{% endfor %})))
-{% endmacro %}
+{% macro bigquery__snapshot_hash_arguments(args) -%}
+  to_hex(md5(concat({% for arg in args %}
+    coalesce(cast({{ arg }} as string), ''){% if not loop.last %}, '|',{% endif -%}
+  {% endfor %}
+  )))
+{%- endmacro %}
 
 {% macro bigquery__create_columns(relation, columns) %}
   {{ adapter.alter_table_add_columns(relation, columns) }}

test/integration/004_simple_snapshot_test/check-snapshots-expected/check_snapshots_test_current.sql

@@ -0,0 +1,51 @@
+
+
+with query as (
+
+    -- check that the current value for id=1 is red
+    select case when (
+        select count(*)
+        from {{ ref('check_cols_cycle') }}
+        where id = 1 and color = 'red' and dbt_valid_to is null
+    ) = 1 then 0 else 1 end as failures
+
+    union all
+
+    -- check that the previous 'red' value for id=1 is invalidated
+    select case when (
+        select count(*)
+        from {{ ref('check_cols_cycle') }}
+        where id = 1 and color = 'red' and dbt_valid_to is not null
+    ) = 1 then 0 else 1 end as failures
+
+    union all
+
+    -- check that there's only one current record for id=2
+    select case when (
+        select count(*)
+        from {{ ref('check_cols_cycle') }}
+        where id = 2 and color = 'pink' and dbt_valid_to is null
+    ) = 1 then 0 else 1 end as failures
+
+    union all
+
+    -- check that the previous value for id=2 is represented
+    select case when (
+        select count(*)
+        from {{ ref('check_cols_cycle') }}
+        where id = 2 and color = 'green' and dbt_valid_to is not null
+    ) = 1 then 0 else 1 end as failures
+
+    union all
+
+    -- check that there are 5 records total in the table
+    select case when (
+        select count(*)
+        from {{ ref('check_cols_cycle') }}
+    ) = 5 then 0 else 1 end as failures
+
+)
+
+select *
+from query
+where failures = 1

test/integration/004_simple_snapshot_test/check-snapshots/check_cols_cycle.sql

@@ -0,0 +1,33 @@
+
+{% snapshot check_cols_cycle %}
+
+    {{
+        config(
+            target_database=database,
+            target_schema=schema,
+            unique_key='id',
+            strategy='check',
+            check_cols=['color']
+        )
+    }}
+
+    {% if var('version') == 1 %}
+
+        select 1 as id, 'red' as color union all
+        select 2 as id, 'green' as color
+
+    {% elif var('version') == 2 %}
+
+        select 1 as id, 'blue' as color union all
+        select 2 as id, 'green' as color
+
+    {% elif var('version') == 3 %}
+
+        select 1 as id, 'red' as color union all
+        select 2 as id, 'pink' as color
+
+    {% else %}
+        {% do exceptions.raise_compiler_error("Got bad version: " ~ var('version')) %}
+    {% endif %}
+
+{% endsnapshot %}

test/integration/004_simple_snapshot_test/test_snapshot_check_cols.py

@@ -0,0 +1,55 @@
+from test.integration.base import DBTIntegrationTest, use_profile
+import dbt.exceptions
+
+
+class TestSimpleSnapshotFiles(DBTIntegrationTest):
+    NUM_SNAPSHOT_MODELS = 1
+
+    @property
+    def schema(self):
+        return "simple_snapshot_004"
+
+    @property
+    def models(self):
+        return "models"
+
+    @property
+    def project_config(self):
+        return {
+            "snapshot-paths": ['check-snapshots'],
+            "test-paths": ['check-snapshots-expected'],
+            "source-paths": [],
+        }
+
+    def test_snapshot_check_cols_cycle(self):
+        results = self.run_dbt(["snapshot", '--vars', 'version: 1'])
+        self.assertEqual(len(results), 1)
+
+        results = self.run_dbt(["snapshot", '--vars', 'version: 2'])
+        self.assertEqual(len(results), 1)
+
+        results = self.run_dbt(["snapshot", '--vars', 'version: 3'])
+        self.assertEqual(len(results), 1)
+
+    def assert_expected(self):
+        self.run_dbt(['test', '--data', '--vars', 'version: 3'])
+
+    @use_profile('snowflake')
+    def test__snowflake__simple_snapshot(self):
+        self.test_snapshot_check_cols_cycle()
+        self.assert_expected()
+
+    @use_profile('postgres')
+    def test__postgres__simple_snapshot(self):
+        self.test_snapshot_check_cols_cycle()
+        self.assert_expected()
+
+    @use_profile('bigquery')
+    def test__bigquery__simple_snapshot(self):
+        self.test_snapshot_check_cols_cycle()
+        self.assert_expected()
+
+    @use_profile('redshift')
+    def test__redshift__simple_snapshot(self):
+        self.test_snapshot_check_cols_cycle()
+        self.assert_expected()