From 7c6de172a2d17b70604dfd788631466667f964fb Mon Sep 17 00:00:00 2001
From: Han Hong <52536323+seunghanhong@users.noreply.github.com>
Date: Sat, 17 Apr 2021 04:32:09 +1000
Subject: [PATCH] support quarter in postgres last day (#333)

---
 integration_tests/data/cross_db/data_last_day.csv         | 1 +
 integration_tests/models/cross_db_utils/test_last_day.sql | 1 +
 macros/cross_db_utils/last_day.sql                        | 8 ++++++--
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/integration_tests/data/cross_db/data_last_day.csv b/integration_tests/data/cross_db/data_last_day.csv
index 186465d8..307fbeb6 100644
--- a/integration_tests/data/cross_db/data_last_day.csv
+++ b/integration_tests/data/cross_db/data_last_day.csv
@@ -1,4 +1,5 @@
 date_day,date_part,result
 2018-01-02,month,2018-01-31
+2018-01-02,quarter,2018-03-31
 2018-01-02,year,2018-12-31
 ,month,
diff --git a/integration_tests/models/cross_db_utils/test_last_day.sql b/integration_tests/models/cross_db_utils/test_last_day.sql
index 5391ae10..fee3a823 100644
--- a/integration_tests/models/cross_db_utils/test_last_day.sql
+++ b/integration_tests/models/cross_db_utils/test_last_day.sql
@@ -8,6 +8,7 @@ with data as (
 select
     case
         when date_part = 'month' then {{ dbt_utils.last_day('date_day', 'month') }}
+        when date_part = 'quarter' then {{ dbt_utils.last_day('date_day', 'quarter') }}
         when date_part = 'year' then {{ dbt_utils.last_day('date_day', 'year') }}
         else null
     end as actual,
diff --git a/macros/cross_db_utils/last_day.sql b/macros/cross_db_utils/last_day.sql
index b66e9d30..160ec2e1 100644
--- a/macros/cross_db_utils/last_day.sql
+++ b/macros/cross_db_utils/last_day.sql
@@ -25,8 +25,12 @@ testing is required to validate that it will work on other dateparts.
 {% macro postgres__last_day(date, datepart) -%}
 
     {%- if datepart == 'quarter' -%}
-    {{ exceptions.raise_compiler_error(
-        "dbt_utils.last_day is not supported for datepart 'quarter' on this adapter") }}
+    -- postgres dateadd does not support quarter interval.
+    cast(
+        {{dbt_utils.dateadd('day', '-1',
+        dbt_utils.dateadd('month', '3', dbt_utils.date_trunc(datepart, date))
+        )}}
+        as date)
     {%- else -%}
     {{dbt_utils.default_last_day(date, datepart)}}
     {%- endif -%}