From 500d4623ba40595ca162c514d0a0d31578a2827a Mon Sep 17 00:00:00 2001
From: Michael Matloka <dev@twixes.com>
Date: Mon, 21 Mar 2022 13:15:50 +0100
Subject: [PATCH] refactor: Yeet `PRIMARY_DB` (#9017)

* refactor: Yeet `PRIMARY_DB`

* Remove `db_backend`

* Eliminate "Analytics database in use"

* Satisfy mypy
---
 .run/Celery.run.xml                           |   4 +-
 .run/Plugin Server.run.xml                    |   3 +-
 .run/PostHog.run.xml                          |   4 +-
 bin/e2e-test-runner                           |   1 -
 bin/plugin-server                             |   4 +-
 bin/start                                     |   1 -
 cypress/fixtures/_preflight.json              |   1 -
 cypress/fixtures/_system_status.json          |   1 -
 docker-compose.hobby.yml                      |   1 -
 ee/clickhouse/client.py                       | 194 ++++++++----------
 ee/pytest.ini                                 |   1 -
 ee/settings.py                                |   6 +-
 .../src/mocks/fixtures/_system_status.json    |   1 -
 frontend/src/types.ts                         |   1 -
 package.json                                  |   4 +-
 plugin-server/package.json                    |   2 +-
 posthog/api/instance_status.py                |   4 -
 posthog/api/test/test_preflight.py            |  19 +-
 posthog/migrations/0187_stale_events.py       |  29 +--
 posthog/settings/celery.py                    |   8 +-
 posthog/settings/data_stores.py               |   3 -
 posthog/settings/overrides.py                 |   9 -
 posthog/settings/service_requirements.py      |   8 +-
 posthog/settings/shell_plus.py                |   5 +-
 posthog/tasks/test/test_org_usage_report.py   |   3 +-
 posthog/tasks/test/test_update_cache.py       |  89 ++++----
 posthog/views.py                              |   1 -
 task-definition.migration.json                |   4 -
 task-definition.web.json                      |   4 -
 task-definition.worker.json                   |   4 -
 30 files changed, 161 insertions(+), 258 deletions(-)

diff --git a/.run/Celery.run.xml b/.run/Celery.run.xml
index 2e9d7c0512d..d56e8fe2bc6 100644
--- a/.run/Celery.run.xml
+++ b/.run/Celery.run.xml
@@ -6,8 +6,6 @@
     <envs>
       <env name="PYTHONUNBUFFERED" value="1" />
       <env name="DEBUG" value="1" />
-      <env name="PRIMARY_DB" value="clickhouse" />
-      <env name="KAFKA_ENABLED" value="true" />
       <env name="CLICKHOUSE_SECURE" value="False" />
       <env name="KAFKA_URL" value="kafka://localhost" />
       <env name="DATABASE_URL" value="postgres://posthog:posthog@localhost:5432/posthog" />
@@ -28,4 +26,4 @@
     <option name="INPUT_FILE" value="" />
     <method v="2" />
   </configuration>
-</component>
\ No newline at end of file
+</component>
diff --git a/.run/Plugin Server.run.xml b/.run/Plugin Server.run.xml
index a755d0d6e23..d44fce97d7c 100644
--- a/.run/Plugin Server.run.xml	
+++ b/.run/Plugin Server.run.xml	
@@ -9,11 +9,10 @@
     <envs>
       <env name="WORKER_CONCURRENCY" value="2" />
       <env name="DATABASE_URL" value="postgres://posthog:posthog@localhost:5432/posthog" />
-      <env name="PRIMARY_DB" value="clickhouse" />
       <env name="KAFKA_ENABLED" value="true" />
       <env name="CLICKHOUSE_SECURE" value="False" />
       <env name="KAFKA_HOSTS" value="localhost:9092" />
     </envs>
     <method v="2" />
   </configuration>
-</component>
\ No newline at end of file
+</component>
diff --git a/.run/PostHog.run.xml b/.run/PostHog.run.xml
index 5de35426a56..3f9cfc21a8e 100644
--- a/.run/PostHog.run.xml
+++ b/.run/PostHog.run.xml
@@ -7,8 +7,6 @@
       <env name="PYTHONUNBUFFERED" value="1" />
       <env name="DJANGO_SETTINGS_MODULE" value="posthog.settings" />
       <env name="DEBUG" value="1" />
-      <env name="PRIMARY_DB" value="clickhouse" />
-      <env name="KAFKA_ENABLED" value="true" />
       <env name="CLICKHOUSE_SECURE" value="False" />
       <env name="KAFKA_URL" value="kafka://localhost" />
       <env name="DATABASE_URL" value="postgres://posthog:posthog@localhost:5432/posthog" />
@@ -31,4 +29,4 @@
     <option name="customRunCommand" value="" />
     <method v="2" />
   </configuration>
-</component>
\ No newline at end of file
+</component>
diff --git a/bin/e2e-test-runner b/bin/e2e-test-runner
index f2c76ded2d3..eb244a5800e 100755
--- a/bin/e2e-test-runner
+++ b/bin/e2e-test-runner
@@ -7,7 +7,6 @@ export NO_RESTART_LOOP=1
 export CYPRESS_BASE_URL=http://localhost:8080
 export OPT_OUT_CAPTURE=1
 export SECURE_COOKIES=0
-export PRIMARY_DB=clickhouse
 export SKIP_SERVICE_VERSION_REQUIREMENTS=1
 export KAFKA_URL=kafka://kafka:9092
 export CLICKHOUSE_DATABASE=posthog_test
diff --git a/bin/plugin-server b/bin/plugin-server
index 1421ae80330..c2c217867f2 100755
--- a/bin/plugin-server
+++ b/bin/plugin-server
@@ -26,8 +26,8 @@ export BASE_DIR=$(dirname $(dirname "$PWD/${0#./}"))
 export KAFKA_URL=${KAFKA_URL:-'kafka://kafka:9092'}
 # Crudely extract netlocs by removing "kafka://" in a compatibility approach
 export KAFKA_HOSTS=${KAFKA_HOSTS:-$(echo $KAFKA_URL | sed -e "s/kafka\(\+ssl\)\{0,1\}:\/\///g")}
-# Check PRIMARY_DB in a compatibility approach
-export KAFKA_ENABLED=${KAFKA_ENABLED:-$([[ $PRIMARY_DB = "clickhouse" ]] && echo "true" || echo "false")}
+# Make sure KAFKA_ENABLED is true - eventually this should be redundant
+export KAFKA_ENABLED="true"
 
 # On _Heroku_, the $WEB_CONCURRENCY env contains suggested number of workers per dyno.
 # Unfortunately we are running a NodeJS app, yet get the value for the "python" buildpack.
diff --git a/bin/start b/bin/start
index 083737e96f4..1282a30e86e 100755
--- a/bin/start
+++ b/bin/start
@@ -5,7 +5,6 @@ set -e
 trap "trap - SIGTERM && kill -- -$$" SIGINT SIGTERM EXIT
 
 export DEBUG=${DEBUG:-1}
-export PRIMARY_DB=clickhouse
 export SKIP_SERVICE_VERSION_REQUIREMENTS=1
 
 ARCH=$(uname -m)
diff --git a/cypress/fixtures/_preflight.json b/cypress/fixtures/_preflight.json
index 1428014c966..0d4967b6d55 100644
--- a/cypress/fixtures/_preflight.json
+++ b/cypress/fixtures/_preflight.json
@@ -8,7 +8,6 @@
     "cloud": false,
     "available_social_auth_providers": { "google-oauth2": false, "github": false, "gitlab": false },
     "ee_available": true,
-    "db_backend": "postgres",
     "available_timezones": {
         "Africa/Abidjan": 0.0,
         "Africa/Accra": 0.0,
diff --git a/cypress/fixtures/_system_status.json b/cypress/fixtures/_system_status.json
index 2ee7d7c167f..d9e88f13d12 100644
--- a/cypress/fixtures/_system_status.json
+++ b/cypress/fixtures/_system_status.json
@@ -1,7 +1,6 @@
 {
     "results": [
         { "key": "posthog_version", "metric": "PostHog version", "value": "1.23.1" },
-        { "key": "analytics_database", "metric": "Analytics database in use", "value": "Postgres" },
         { "key": "ingestion_server", "metric": "Event ingestion via", "value": "Plugin Server" },
         { "key": "plugin_sever_alive", "metric": "Plugin server alive", "value": true },
         { "key": "plugin_sever_version", "metric": "Plugin server version", "value": "0.15.5" },
diff --git a/docker-compose.hobby.yml b/docker-compose.hobby.yml
index da801f7982c..6f9bab2c8f7 100644
--- a/docker-compose.hobby.yml
+++ b/docker-compose.hobby.yml
@@ -67,7 +67,6 @@ services:
             CLICKHOUSE_DATABASE: 'posthog'
             CLICKHOUSE_SECURE: 'false'
             CLICKHOUSE_VERIFY: 'false'
-            PRIMARY_DB: 'clickhouse'
             KAFKA_URL: 'kafka://kafka'
             REDIS_URL: 'redis://redis:6379/'
             SECRET_KEY: $POSTHOG_SECRET
diff --git a/ee/clickhouse/client.py b/ee/clickhouse/client.py
index c576af65249..277b504e819 100644
--- a/ee/clickhouse/client.py
+++ b/ee/clickhouse/client.py
@@ -18,7 +18,6 @@ from sentry_sdk.api import capture_exception
 from ee.clickhouse.errors import wrap_query_error
 from ee.clickhouse.timer import get_timer_thread
 from posthog import redis
-from posthog.constants import AnalyticsDBMS
 from posthog.internal_metrics import incr, timing
 from posthog.settings import (
     CLICKHOUSE_ASYNC,
@@ -31,7 +30,6 @@ from posthog.settings import (
     CLICKHOUSE_SECURE,
     CLICKHOUSE_USER,
     CLICKHOUSE_VERIFY,
-    PRIMARY_DB,
     TEST,
 )
 from posthog.utils import get_safe_cache
@@ -80,122 +78,106 @@ def make_ch_pool(**overrides) -> ChPool:
     return ChPool(**kwargs)
 
 
-if PRIMARY_DB != AnalyticsDBMS.CLICKHOUSE:
-    ch_client = None  # type: Client
+if not TEST and CLICKHOUSE_ASYNC:
+    ch_client = Client(
+        host=CLICKHOUSE_HOST,
+        database=CLICKHOUSE_DATABASE,
+        secure=CLICKHOUSE_SECURE,
+        user=CLICKHOUSE_USER,
+        password=CLICKHOUSE_PASSWORD,
+        ca_certs=CLICKHOUSE_CA,
+        verify=CLICKHOUSE_VERIFY,
+    )
 
-    class ClickHouseNotConfigured(NotImplementedError):
-        def __init__(self, msg='This function only works if PRIMARY_DB is set to indicate ClickHouse!"', *args):
-            super().__init__(msg, *args)
+    ch_pool = make_ch_pool()
 
-    def async_execute(query, args=None, settings=None, with_column_types=False):
-        raise ClickHouseNotConfigured()
-
-    def sync_execute(query, args=None, settings=None, with_column_types=False):
-        raise ClickHouseNotConfigured()
-
-    def cache_sync_execute(query, args=None, redis_client=None, ttl=None, settings=None, with_column_types=False):
-        raise ClickHouseNotConfigured()
+    @async_to_sync
+    async def async_execute(query, args=None, settings=None, with_column_types=False):
+        loop = asyncio.get_event_loop()
+        task = loop.create_task(ch_client.execute(query, args, settings=settings, with_column_types=with_column_types))
+        return task
 
 
 else:
-    if not TEST and CLICKHOUSE_ASYNC:
-        ch_client = Client(
-            host=CLICKHOUSE_HOST,
-            database=CLICKHOUSE_DATABASE,
-            secure=CLICKHOUSE_SECURE,
-            user=CLICKHOUSE_USER,
-            password=CLICKHOUSE_PASSWORD,
-            ca_certs=CLICKHOUSE_CA,
-            verify=CLICKHOUSE_VERIFY,
-        )
+    # if this is a test use the sync client
+    ch_client = SyncClient(
+        host=CLICKHOUSE_HOST,
+        database=CLICKHOUSE_DATABASE,
+        secure=CLICKHOUSE_SECURE,
+        user=CLICKHOUSE_USER,
+        password=CLICKHOUSE_PASSWORD,
+        ca_certs=CLICKHOUSE_CA,
+        verify=CLICKHOUSE_VERIFY,
+        settings={"mutations_sync": "1"} if TEST else {},
+    )
 
-        ch_pool = make_ch_pool()
+    ch_pool = make_ch_pool()
 
-        @async_to_sync
-        async def async_execute(query, args=None, settings=None, with_column_types=False):
-            loop = asyncio.get_event_loop()
-            task = loop.create_task(
-                ch_client.execute(query, args, settings=settings, with_column_types=with_column_types)
-            )
-            return task
+    def async_execute(query, args=None, settings=None, with_column_types=False):  # type: ignore
+        return sync_execute(query, args, settings=settings, with_column_types=with_column_types)
 
+
+def cache_sync_execute(query, args=None, redis_client=None, ttl=CACHE_TTL, settings=None, with_column_types=False):
+    if not redis_client:
+        redis_client = redis.get_client()
+    key = _key_hash(query, args)
+    if redis_client.exists(key):
+        result = _deserialize(redis_client.get(key))
+        return result
     else:
-        # if this is a test use the sync client
-        ch_client = SyncClient(
-            host=CLICKHOUSE_HOST,
-            database=CLICKHOUSE_DATABASE,
-            secure=CLICKHOUSE_SECURE,
-            user=CLICKHOUSE_USER,
-            password=CLICKHOUSE_PASSWORD,
-            ca_certs=CLICKHOUSE_CA,
-            verify=CLICKHOUSE_VERIFY,
-            settings={"mutations_sync": "1"} if TEST else {},
-        )
-
-        ch_pool = make_ch_pool()
-
-        def async_execute(query, args=None, settings=None, with_column_types=False):
-            return sync_execute(query, args, settings=settings, with_column_types=with_column_types)
-
-    def cache_sync_execute(query, args=None, redis_client=None, ttl=CACHE_TTL, settings=None, with_column_types=False):
-        if not redis_client:
-            redis_client = redis.get_client()
-        key = _key_hash(query, args)
-        if redis_client.exists(key):
-            result = _deserialize(redis_client.get(key))
-            return result
-        else:
-            result = sync_execute(query, args, settings=settings, with_column_types=with_column_types)
-            redis_client.set(key, _serialize(result), ex=ttl)
-            return result
-
-    def sync_execute(query, args=None, settings=None, with_column_types=False):
-        with ch_pool.get_client() as client:
-            start_time = perf_counter()
-
-            prepared_sql, prepared_args, tags = _prepare_query(client=client, query=query, args=args)
-
-            timeout_task = QUERY_TIMEOUT_THREAD.schedule(_notify_of_slow_query_failure, tags)
-
-            try:
-                result = client.execute(
-                    prepared_sql, params=prepared_args, settings=settings, with_column_types=with_column_types
-                )
-            except Exception as err:
-                err = wrap_query_error(err)
-                tags["failed"] = True
-                tags["reason"] = type(err).__name__
-                incr("clickhouse_sync_execution_failure", tags=tags)
-
-                raise err
-            finally:
-                execution_time = perf_counter() - start_time
-
-                QUERY_TIMEOUT_THREAD.cancel(timeout_task)
-                timing("clickhouse_sync_execution_time", execution_time * 1000.0, tags=tags)
-
-                if app_settings.SHELL_PLUS_PRINT_SQL:
-                    print("Execution time: %.6fs" % (execution_time,))
-                if _request_information is not None and _request_information.get("save", False):
-                    save_query(prepared_sql, execution_time)
+        result = sync_execute(query, args, settings=settings, with_column_types=with_column_types)
+        redis_client.set(key, _serialize(result), ex=ttl)
         return result
 
-    def substitute_params(query, params):
-        """
-        Helper method to ease rendering of sql clickhouse queries progressively.
-        For example, there are many places where we construct queries to be used
-        as subqueries of others. Each time we generate a subquery we also pass
-        up the "bound" parameters to be used to render the query, which
-        otherwise only happens at the point of calling clickhouse via the
-        clickhouse_driver `Client`.
 
-        This results in sometimes large lists of parameters with no relevance to
-        the containing query being passed up. Rather than do this, we can
-        instead "render" the subqueries prior to using as a subquery, so our
-        containing code is only responsible for it's parameters, and we can
-        avoid any potential param collisions.
-        """
-        return cast(SyncClient, ch_client).substitute_params(query, params)
+def sync_execute(query, args=None, settings=None, with_column_types=False):
+    with ch_pool.get_client() as client:
+        start_time = perf_counter()
+
+        prepared_sql, prepared_args, tags = _prepare_query(client=client, query=query, args=args)
+
+        timeout_task = QUERY_TIMEOUT_THREAD.schedule(_notify_of_slow_query_failure, tags)
+
+        try:
+            result = client.execute(
+                prepared_sql, params=prepared_args, settings=settings, with_column_types=with_column_types
+            )
+        except Exception as err:
+            err = wrap_query_error(err)
+            tags["failed"] = True
+            tags["reason"] = type(err).__name__
+            incr("clickhouse_sync_execution_failure", tags=tags)
+
+            raise err
+        finally:
+            execution_time = perf_counter() - start_time
+
+            QUERY_TIMEOUT_THREAD.cancel(timeout_task)
+            timing("clickhouse_sync_execution_time", execution_time * 1000.0, tags=tags)
+
+            if app_settings.SHELL_PLUS_PRINT_SQL:
+                print("Execution time: %.6fs" % (execution_time,))
+            if _request_information is not None and _request_information.get("save", False):
+                save_query(prepared_sql, execution_time)
+    return result
+
+
+def substitute_params(query, params):
+    """
+    Helper method to ease rendering of sql clickhouse queries progressively.
+    For example, there are many places where we construct queries to be used
+    as subqueries of others. Each time we generate a subquery we also pass
+    up the "bound" parameters to be used to render the query, which
+    otherwise only happens at the point of calling clickhouse via the
+    clickhouse_driver `Client`.
+
+    This results in sometimes large lists of parameters with no relevance to
+    the containing query being passed up. Rather than do this, we can
+    instead "render" the subqueries prior to using as a subquery, so our
+    containing code is only responsible for it's parameters, and we can
+    avoid any potential param collisions.
+    """
+    return cast(SyncClient, ch_client).substitute_params(query, params)
 
 
 def _prepare_query(client: SyncClient, query: str, args: QueryArgs):
diff --git a/ee/pytest.ini b/ee/pytest.ini
index b8fa0695ddf..4af882084e4 100644
--- a/ee/pytest.ini
+++ b/ee/pytest.ini
@@ -1,6 +1,5 @@
 [pytest]
 env =
-    PRIMARY_DB=clickhouse
     DEBUG=1
     TEST=1
 DJANGO_SETTINGS_MODULE = posthog.settings
diff --git a/ee/settings.py b/ee/settings.py
index 718266c8537..d5e1336c12a 100644
--- a/ee/settings.py
+++ b/ee/settings.py
@@ -5,8 +5,7 @@ import os
 from typing import Dict, List
 
 from ee.kafka_client.topics import KAFKA_EVENTS_PLUGIN_INGESTION as DEFAULT_KAFKA_EVENTS_PLUGIN_INGESTION
-from posthog.constants import AnalyticsDBMS
-from posthog.settings import AUTHENTICATION_BACKENDS, PRIMARY_DB, SITE_URL, TEST, get_from_env
+from posthog.settings import AUTHENTICATION_BACKENDS, SITE_URL, TEST, get_from_env
 from posthog.utils import print_warning, str_to_bool
 
 # Zapier REST hooks
@@ -72,9 +71,8 @@ AUTHENTICATION_BACKENDS = AUTHENTICATION_BACKENDS + [
 
 SSO_ENFORCEMENT = get_from_env("SSO_ENFORCEMENT", "saml" if SAML_ENFORCED else None, optional=True)
 
-
 # ClickHouse and Kafka
-KAFKA_ENABLED = PRIMARY_DB == AnalyticsDBMS.CLICKHOUSE and not TEST
+KAFKA_ENABLED = not TEST
 
 # Schedule to run column materialization on. Follows crontab syntax.
 # Use empty string to prevent from materializing
diff --git a/frontend/src/mocks/fixtures/_system_status.json b/frontend/src/mocks/fixtures/_system_status.json
index 2ee7d7c167f..d9e88f13d12 100644
--- a/frontend/src/mocks/fixtures/_system_status.json
+++ b/frontend/src/mocks/fixtures/_system_status.json
@@ -1,7 +1,6 @@
 {
     "results": [
         { "key": "posthog_version", "metric": "PostHog version", "value": "1.23.1" },
-        { "key": "analytics_database", "metric": "Analytics database in use", "value": "Postgres" },
         { "key": "ingestion_server", "metric": "Event ingestion via", "value": "Plugin Server" },
         { "key": "plugin_sever_alive", "metric": "Plugin server alive", "value": true },
         { "key": "plugin_sever_version", "metric": "Plugin server version", "value": "0.15.5" },
diff --git a/frontend/src/types.ts b/frontend/src/types.ts
index 9a9d244c60a..b4a2a13b262 100644
--- a/frontend/src/types.ts
+++ b/frontend/src/types.ts
@@ -1282,7 +1282,6 @@ export interface PreflightStatus {
     demo: boolean
     celery: boolean
     realm: Realm
-    db_backend?: 'postgres' | 'clickhouse'
     available_social_auth_providers: AuthBackends
     available_timezones?: Record<string, number>
     opt_out_capture?: boolean
diff --git a/package.json b/package.json
index f5c44492239..16575c03f9e 100644
--- a/package.json
+++ b/package.json
@@ -58,8 +58,8 @@
         "arm64:services:start": "docker-compose -f docker-compose.arm64.yml up zookeeper kafka clickhouse",
         "arm64:services:stop": "docker-compose -f docker-compose.arm64.yml down",
         "arm64:services:clean": "docker-compose -f docker-compose.arm64.yml rm -v zookeeper kafka clickhouse",
-        "dev:migrate:postgres": "export DEBUG=1 PRIMARY_DB=clickhouse && source env/bin/activate && python manage.py migrate",
-        "dev:migrate:clickhouse": "export DEBUG=1 PRIMARY_DB=clickhouse && source env/bin/activate && python manage.py migrate_clickhouse"
+        "dev:migrate:postgres": "export DEBUG=1 && source env/bin/activate && python manage.py migrate",
+        "dev:migrate:clickhouse": "export DEBUG=1 && source env/bin/activate && python manage.py migrate_clickhouse"
     },
     "dependencies": {
         "@babel/core": "^7.10.4",
diff --git a/plugin-server/package.json b/plugin-server/package.json
index 4560bbfcedb..271817697d5 100644
--- a/plugin-server/package.json
+++ b/plugin-server/package.json
@@ -31,7 +31,7 @@
         "prettier:check": "prettier --check .",
         "prepare": "yarn protobuf:compile",
         "prepublishOnly": "yarn build",
-        "setup:dev:clickhouse": "cd .. && export DEBUG=1 PRIMARY_DB=clickhouse && python manage.py migrate_clickhouse",
+        "setup:dev:clickhouse": "cd .. && export DEBUG=1 && python manage.py migrate_clickhouse",
         "setup:test": "cd .. && export TEST=1 && python manage.py setup_test_environment",
         "services:start": "cd .. && docker-compose -f docker-compose.dev.yml up zookeeper kafka clickhouse",
         "services:stop": "cd .. && docker-compose -f docker-compose.dev.yml down",
diff --git a/posthog/api/instance_status.py b/posthog/api/instance_status.py
index 4472da42459..ebe494178f3 100644
--- a/posthog/api/instance_status.py
+++ b/posthog/api/instance_status.py
@@ -53,10 +53,6 @@ class InstanceStatusViewSet(viewsets.ViewSet):
                 }
             )
 
-        metrics.append(
-            {"key": "analytics_database", "metric": "Analytics database in use", "value": "ClickHouse",}
-        )
-
         metrics.append(
             {"key": "plugin_sever_alive", "metric": "Plugin server alive", "value": is_plugin_server_alive()}
         )
diff --git a/posthog/api/test/test_preflight.py b/posthog/api/test/test_preflight.py
index 947c6925ce8..3b8b51fb11d 100644
--- a/posthog/api/test/test_preflight.py
+++ b/posthog/api/test/test_preflight.py
@@ -5,7 +5,6 @@ from constance.test import override_config
 from django.utils import timezone
 from rest_framework import status
 
-from posthog.constants import AnalyticsDBMS
 from posthog.models.organization import Organization, OrganizationInvite
 from posthog.test.base import APIBaseTest
 from posthog.version import VERSION
@@ -24,7 +23,7 @@ class TestPreflight(APIBaseTest):
         For security purposes, the information contained in an unauthenticated preflight request is minimal.
         """
         self.client.logout()
-        with self.settings(PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE, MULTI_TENANCY=False):
+        with self.settings(MULTI_TENANCY=False):
             response = self.client.get("/_preflight/")
 
         self.assertEqual(response.status_code, status.HTTP_200_OK)
@@ -53,9 +52,7 @@ class TestPreflight(APIBaseTest):
 
     def test_preflight_request(self):
         with self.settings(
-            PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE,
-            MULTI_TENANCY=False,
-            INSTANCE_PREFERENCES=self.instance_preferences(debug_queries=True),
+            MULTI_TENANCY=False, INSTANCE_PREFERENCES=self.instance_preferences(debug_queries=True),
         ):
             response = self.client.get("/_preflight/")
             self.assertEqual(response.status_code, status.HTTP_200_OK)
@@ -74,7 +71,6 @@ class TestPreflight(APIBaseTest):
                     "cloud": False,
                     "demo": False,
                     "realm": "hosted-clickhouse",
-                    "db_backend": "clickhouse",
                     "available_social_auth_providers": {
                         "google-oauth2": False,
                         "github": False,
@@ -100,7 +96,7 @@ class TestPreflight(APIBaseTest):
 
         self.client.logout()  # make sure it works anonymously
 
-        with self.settings(MULTI_TENANCY=True, PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE):
+        with self.settings(MULTI_TENANCY=True):
             response = self.client.get("/_preflight/")
             self.assertEqual(response.status_code, status.HTTP_200_OK)
 
@@ -129,7 +125,7 @@ class TestPreflight(APIBaseTest):
 
     @pytest.mark.ee
     def test_cloud_preflight_request(self):
-        with self.settings(MULTI_TENANCY=True, PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE, SITE_URL="https://app.posthog.com"):
+        with self.settings(MULTI_TENANCY=True, SITE_URL="https://app.posthog.com"):
             response = self.client.get("/_preflight/")
             self.assertEqual(response.status_code, status.HTTP_200_OK)
             response = response.json()
@@ -147,7 +143,6 @@ class TestPreflight(APIBaseTest):
                     "cloud": True,
                     "demo": False,
                     "realm": "cloud",
-                    "db_backend": "clickhouse",
                     "available_social_auth_providers": {
                         "google-oauth2": False,
                         "github": False,
@@ -174,7 +169,6 @@ class TestPreflight(APIBaseTest):
             SOCIAL_AUTH_GOOGLE_OAUTH2_KEY="test_key",
             SOCIAL_AUTH_GOOGLE_OAUTH2_SECRET="test_secret",
             MULTI_TENANCY=True,
-            PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE,
             INSTANCE_PREFERENCES=self.instance_preferences(disable_paid_fs=True),
         ):
             response = self.client.get("/_preflight/")
@@ -194,7 +188,6 @@ class TestPreflight(APIBaseTest):
                     "cloud": True,
                     "demo": False,
                     "realm": "cloud",
-                    "db_backend": "clickhouse",
                     "available_social_auth_providers": {
                         "google-oauth2": True,
                         "github": False,
@@ -218,7 +211,7 @@ class TestPreflight(APIBaseTest):
     def test_demo(self):
         self.client.logout()  # make sure it works anonymously
 
-        with self.settings(PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE, DEMO=True):
+        with self.settings(DEMO=True):
             response = self.client.get("/_preflight/")
 
         self.assertEqual(response.status_code, status.HTTP_200_OK)
@@ -257,7 +250,7 @@ class TestPreflight(APIBaseTest):
 
         self.client.logout()  # make sure it works anonymously
 
-        with self.settings(PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE, SAML_CONFIGURED=True):
+        with self.settings(SAML_CONFIGURED=True):
             response = self.client.get("/_preflight/")
             self.assertEqual(response.status_code, status.HTTP_200_OK)
 
diff --git a/posthog/migrations/0187_stale_events.py b/posthog/migrations/0187_stale_events.py
index 470ffe7f270..be5b91ee919 100644
--- a/posthog/migrations/0187_stale_events.py
+++ b/posthog/migrations/0187_stale_events.py
@@ -1,10 +1,7 @@
 # Generated by Django 3.2.5 on 2021-11-30 08:23
 import django.utils.timezone
-from django.conf import settings
 from django.db import migrations, models
 
-from posthog.constants import AnalyticsDBMS
-
 
 def set_created_at(apps, schema_editor):
 
@@ -16,25 +13,15 @@ def set_created_at(apps, schema_editor):
     EventDefinition = apps.get_model("posthog", "EventDefinition")
     for instance in EventDefinition.objects.filter(created_at=None):
         created_at = None
-        if settings.PRIMARY_DB == AnalyticsDBMS.POSTGRES:
-            Event = apps.get_model("posthog", "Event")
-            event_instance = (
-                Event.objects.select("timestamp")
-                .filter(team=instance.team, name=instance.name)
-                .order_by("timestamp")
-                .first()
+        result = None
+        if sync_execute:
+            result = sync_execute(
+                "SELECT timestamp FROM events where team_id=%(team_id)s AND event=%(event)s"
+                " order by timestamp limit 1",
+                {"team_id": instance.team.pk, "event": instance.name,},
             )
-            if event_instance:
-                created_at = event_instance.timestamp
-        else:
-            if sync_execute:
-                result = sync_execute(
-                    "SELECT timestamp FROM events where team_id=%(team_id)s AND event=%(event)s"
-                    " order by timestamp limit 1",
-                    {"team_id": instance.team.pk, "event": instance.name,},
-                )
-            if result:
-                created_at = result[0][0]
+        if result:
+            created_at = result[0][0]
 
         if created_at:
             instance.created_at = created_at
diff --git a/posthog/settings/celery.py b/posthog/settings/celery.py
index 4b4bcc21cfd..0e37c61078e 100644
--- a/posthog/settings/celery.py
+++ b/posthog/settings/celery.py
@@ -2,15 +2,14 @@ from datetime import timedelta
 
 from kombu import Exchange, Queue
 
-from posthog.constants import AnalyticsDBMS
 from posthog.settings.base_variables import TEST
-from posthog.settings.data_stores import PRIMARY_DB, REDIS_URL
+from posthog.settings.data_stores import REDIS_URL
 
 # Only listen to the default queue "celery", unless overridden via the cli
 # NB! This is set to explicitly exclude the "posthog-plugins" queue, handled by a nodejs process
 CELERY_QUEUES = (Queue("celery", Exchange("celery"), "celery"),)
 CELERY_DEFAULT_QUEUE = "celery"
-CELERY_IMPORTS = []
+CELERY_IMPORTS = ["ee.tasks.materialized_columns"]
 CELERY_BROKER_URL = REDIS_URL  # celery connects to redis
 CELERY_BEAT_MAX_LOOP_INTERVAL = 30  # sleep max 30sec before checking for new periodic events
 CELERY_RESULT_BACKEND = REDIS_URL  # stores results for lookup when processing
@@ -18,9 +17,6 @@ CELERY_IGNORE_RESULT = True  # only applies to delay(), must do @shared_task(ign
 CELERY_RESULT_EXPIRES = timedelta(days=4)  # expire tasks after 4 days instead of the default 1
 REDBEAT_LOCK_TIMEOUT = 45  # keep distributed beat lock for 45sec
 
-if PRIMARY_DB == AnalyticsDBMS.CLICKHOUSE:
-    CELERY_IMPORTS.append("ee.tasks.materialized_columns")
-
 if TEST:
     import celery
 
diff --git a/posthog/settings/data_stores.py b/posthog/settings/data_stores.py
index 71238b1f721..c26bb3bcdbf 100644
--- a/posthog/settings/data_stores.py
+++ b/posthog/settings/data_stores.py
@@ -4,7 +4,6 @@ from urllib.parse import urlparse
 import dj_database_url
 from django.core.exceptions import ImproperlyConfigured
 
-from posthog.constants import AnalyticsDBMS
 from posthog.settings.base_variables import DEBUG, IS_COLLECT_STATIC, TEST
 from posthog.settings.utils import get_from_env, str_to_bool
 
@@ -116,8 +115,6 @@ KAFKA_HOSTS_FOR_CLICKHOUSE = _parse_kafka_hosts(os.getenv("KAFKA_URL_FOR_CLICKHO
 
 KAFKA_BASE64_KEYS = get_from_env("KAFKA_BASE64_KEYS", False, type_cast=str_to_bool)
 
-PRIMARY_DB = AnalyticsDBMS.CLICKHOUSE
-
 # The last case happens when someone upgrades Heroku but doesn't have Redis installed yet. Collectstatic gets called before we can provision Redis.
 if TEST or DEBUG or IS_COLLECT_STATIC:
     REDIS_URL = os.getenv("REDIS_URL", "redis://localhost/")
diff --git a/posthog/settings/overrides.py b/posthog/settings/overrides.py
index fdc7a8ff515..5e5191a2a91 100644
--- a/posthog/settings/overrides.py
+++ b/posthog/settings/overrides.py
@@ -36,12 +36,3 @@ if runner:
         print("Running in test mode. Setting DEBUG and TEST environment variables.")
         os.environ["DEBUG"] = "1"
         os.environ["TEST"] = "1"
-
-        try:
-            path = sys.argv[2] if cmd == "test" else sys.argv[3]
-            if path.startswith("ee"):
-                print("Running EE tests. Setting clickhouse as primary database.")
-                os.environ["PRIMARY_DB"] = "clickhouse"
-        except IndexError:
-            # there was no path, we don't want to set PRIMARY_DB
-            pass
diff --git a/posthog/settings/service_requirements.py b/posthog/settings/service_requirements.py
index dad8f9da427..1b30905a1bd 100644
--- a/posthog/settings/service_requirements.py
+++ b/posthog/settings/service_requirements.py
@@ -1,6 +1,4 @@
-from posthog.constants import AnalyticsDBMS
 from posthog.settings.base_variables import DEBUG, IS_COLLECT_STATIC, TEST
-from posthog.settings.data_stores import PRIMARY_DB
 from posthog.settings.utils import get_from_env, print_warning, str_to_bool
 from posthog.version_requirement import ServiceVersionRequirement
 
@@ -14,9 +12,5 @@ if SKIP_SERVICE_VERSION_REQUIREMENTS and not (TEST or DEBUG):
 SERVICE_VERSION_REQUIREMENTS = [
     ServiceVersionRequirement(service="postgresql", supported_version=">=11.0.0,<=14.1.0",),
     ServiceVersionRequirement(service="redis", supported_version=">=5.0.0,<=6.3.0",),
+    ServiceVersionRequirement(service="clickhouse", supported_version=">=21.6.0,<21.12.0"),
 ]
-
-if PRIMARY_DB == AnalyticsDBMS.CLICKHOUSE:
-    SERVICE_VERSION_REQUIREMENTS = SERVICE_VERSION_REQUIREMENTS + [
-        ServiceVersionRequirement(service="clickhouse", supported_version=">=21.6.0,<21.12.0"),
-    ]
diff --git a/posthog/settings/shell_plus.py b/posthog/settings/shell_plus.py
index 4eb8b411679..dd7a42b32a7 100644
--- a/posthog/settings/shell_plus.py
+++ b/posthog/settings/shell_plus.py
@@ -1,5 +1,3 @@
-from posthog.constants import AnalyticsDBMS
-from posthog.settings.data_stores import PRIMARY_DB
 from posthog.settings.utils import get_from_env, str_to_bool
 
 # shell_plus settings
@@ -11,5 +9,4 @@ SHELL_PLUS_POST_IMPORTS = [
     ("posthog.models.property", ("Property",)),
 ]
 
-if PRIMARY_DB == AnalyticsDBMS.CLICKHOUSE:
-    SHELL_PLUS_POST_IMPORTS.append(("ee.clickhouse.client", ("sync_execute",)))
+SHELL_PLUS_POST_IMPORTS.append(("ee.clickhouse.client", ("sync_execute",)))
diff --git a/posthog/tasks/test/test_org_usage_report.py b/posthog/tasks/test/test_org_usage_report.py
index dd8b0297521..a1d7e2c4b93 100644
--- a/posthog/tasks/test/test_org_usage_report.py
+++ b/posthog/tasks/test/test_org_usage_report.py
@@ -9,7 +9,6 @@ from freezegun import freeze_time
 from ee.clickhouse.models.event import create_event
 from ee.clickhouse.models.group import create_group
 from ee.clickhouse.util import ClickhouseTestMixin
-from posthog.constants import AnalyticsDBMS
 from posthog.models import Organization, Person, Team, User
 from posthog.models.group_type_mapping import GroupTypeMapping
 from posthog.models.organization import OrganizationMembership
@@ -74,7 +73,7 @@ class TestOrganizationUsageReport(APIBaseTest, ClickhouseTestMixin):
             self.assertEqual(org_report["group_types_total"], 0)
             self.assertEqual(org_report["event_count_with_groups_month"], 0)
 
-        with self.settings(USE_TZ=False, PRIMARY_DB=AnalyticsDBMS.CLICKHOUSE):
+        with self.settings(USE_TZ=False):
             with freeze_time("2020-11-02"):
                 _create_person("old_user1", team=default_team)
                 _create_person("old_user2", team=default_team)
diff --git a/posthog/tasks/test/test_update_cache.py b/posthog/tasks/test/test_update_cache.py
index 95d98c131f4..c391bca9607 100644
--- a/posthog/tasks/test/test_update_cache.py
+++ b/posthog/tasks/test/test_update_cache.py
@@ -144,55 +144,54 @@ class TestUpdateCache(APIBaseTest):
             }
         )
 
-        with self.settings(PRIMARY_DB="clickhouse"):
-            filter = base_filter
-            funnel_mock.return_value.run.return_value = {}
-            update_cache_item(
-                generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
-                CacheType.FUNNEL,
-                {"filter": filter.toJSON(), "team_id": self.team.pk,},
-            )
-            funnel_mock.assert_called_once()
+        filter = base_filter
+        funnel_mock.return_value.run.return_value = {}
+        update_cache_item(
+            generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
+            CacheType.FUNNEL,
+            {"filter": filter.toJSON(), "team_id": self.team.pk,},
+        )
+        funnel_mock.assert_called_once()
 
-            # trends funnel
-            filter = base_filter.with_data({"funnel_viz_type": "trends"})
-            funnel_trends_mock.return_value.run.return_value = {}
-            update_cache_item(
-                generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
-                CacheType.FUNNEL,
-                {"filter": filter.toJSON(), "team_id": self.team.pk,},
-            )
-            funnel_trends_mock.assert_called_once()
+        # trends funnel
+        filter = base_filter.with_data({"funnel_viz_type": "trends"})
+        funnel_trends_mock.return_value.run.return_value = {}
+        update_cache_item(
+            generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
+            CacheType.FUNNEL,
+            {"filter": filter.toJSON(), "team_id": self.team.pk,},
+        )
+        funnel_trends_mock.assert_called_once()
 
-            # time to convert funnel
-            filter = base_filter.with_data({"funnel_viz_type": "time_to_convert", "funnel_order_type": "strict"})
-            funnel_time_to_convert_mock.return_value.run.return_value = {}
-            update_cache_item(
-                generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
-                CacheType.FUNNEL,
-                {"filter": filter.toJSON(), "team_id": self.team.pk,},
-            )
-            funnel_time_to_convert_mock.assert_called_once()
+        # time to convert funnel
+        filter = base_filter.with_data({"funnel_viz_type": "time_to_convert", "funnel_order_type": "strict"})
+        funnel_time_to_convert_mock.return_value.run.return_value = {}
+        update_cache_item(
+            generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
+            CacheType.FUNNEL,
+            {"filter": filter.toJSON(), "team_id": self.team.pk,},
+        )
+        funnel_time_to_convert_mock.assert_called_once()
 
-            # strict funnel
-            filter = base_filter.with_data({"funnel_order_type": "strict"})
-            funnel_strict_mock.return_value.run.return_value = {}
-            update_cache_item(
-                generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
-                CacheType.FUNNEL,
-                {"filter": filter.toJSON(), "team_id": self.team.pk,},
-            )
-            funnel_strict_mock.assert_called_once()
+        # strict funnel
+        filter = base_filter.with_data({"funnel_order_type": "strict"})
+        funnel_strict_mock.return_value.run.return_value = {}
+        update_cache_item(
+            generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
+            CacheType.FUNNEL,
+            {"filter": filter.toJSON(), "team_id": self.team.pk,},
+        )
+        funnel_strict_mock.assert_called_once()
 
-            # unordered funnel
-            filter = base_filter.with_data({"funnel_order_type": "unordered"})
-            funnel_unordered_mock.return_value.run.return_value = {}
-            update_cache_item(
-                generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
-                CacheType.FUNNEL,
-                {"filter": filter.toJSON(), "team_id": self.team.pk,},
-            )
-            funnel_unordered_mock.assert_called_once()
+        # unordered funnel
+        filter = base_filter.with_data({"funnel_order_type": "unordered"})
+        funnel_unordered_mock.return_value.run.return_value = {}
+        update_cache_item(
+            generate_cache_key("{}_{}".format(filter.toJSON(), self.team.pk)),
+            CacheType.FUNNEL,
+            {"filter": filter.toJSON(), "team_id": self.team.pk,},
+        )
+        funnel_unordered_mock.assert_called_once()
 
     def _test_refresh_dashboard_cache_types(
         self, filter: FilterType, cache_type: CacheType, patch_update_cache_item: MagicMock,
diff --git a/posthog/views.py b/posthog/views.py
index cb434a5c237..18f05401598 100644
--- a/posthog/views.py
+++ b/posthog/views.py
@@ -111,7 +111,6 @@ def preflight_check(request: HttpRequest) -> JsonResponse:
     if request.user.is_authenticated:
         response = {
             **response,
-            "db_backend": settings.PRIMARY_DB.value,
             "available_timezones": get_available_timezones_with_offsets(),
             "opt_out_capture": os.environ.get("OPT_OUT_CAPTURE", False),
             "posthog_version": VERSION,
diff --git a/task-definition.migration.json b/task-definition.migration.json
index 96060df23f0..b184a37ff21 100644
--- a/task-definition.migration.json
+++ b/task-definition.migration.json
@@ -72,10 +72,6 @@
                     "name": "KAFKA_BASE64_KEYS",
                     "value": "True"
                 },
-                {
-                    "name": "PRIMARY_DB",
-                    "value": "clickhouse"
-                },
                 {
                     "name": "SITE_URL",
                     "value": "https://app.posthog.com"
diff --git a/task-definition.web.json b/task-definition.web.json
index 738a04ce577..9db00cba24c 100644
--- a/task-definition.web.json
+++ b/task-definition.web.json
@@ -78,10 +78,6 @@
                     "name": "KAFKA_BASE64_KEYS",
                     "value": "True"
                 },
-                {
-                    "name": "PRIMARY_DB",
-                    "value": "clickhouse"
-                },
                 {
                     "name": "SITE_URL",
                     "value": "https://app.posthog.com"
diff --git a/task-definition.worker.json b/task-definition.worker.json
index 2f5d7859ca8..31a1252760d 100644
--- a/task-definition.worker.json
+++ b/task-definition.worker.json
@@ -72,10 +72,6 @@
                     "name": "KAFKA_BASE64_KEYS",
                     "value": "True"
                 },
-                {
-                    "name": "PRIMARY_DB",
-                    "value": "clickhouse"
-                },
                 {
                     "name": "SITE_URL",
                     "value": "https://app.posthog.com"