feat(web-analytics): Turn timezones into UTC offsets instead of timezone names

frontend/src/scenes/web-analytics/tiles/WebAnalyticsTile.tsx

@@ -19,6 +19,23 @@ import { DataTableNode, InsightVizNode, NodeKind, QuerySchema, WebStatsBreakdown
 import { QueryContext, QueryContextColumnComponent, QueryContextColumnTitleComponent } from '~/queries/types'
 import { ChartDisplayType, GraphPointPayload, InsightLogicProps, ProductKey, PropertyFilterType } from '~/types'
 
+const toUtcOffsetFormat = (value: number): string => {
+    if (value === 0) {
+        return 'UTC'
+    }
+
+    const integerPart = Math.floor(value)
+    const sign = integerPart > 0 ? '+' : '-'
+
+    // India has half-hour offsets, and Australia has 45-minute offsets, why?
+    const decimalPart = value - integerPart
+    const decimalPartAsMinutes = decimalPart * 60
+    const formattedMinutes = decimalPartAsMinutes > 0 ? `:${decimalPartAsMinutes}` : ''
+
+    // E.g. UTC-3, UTC, UTC+5:30, UTC+11:45
+    return `UTC${sign}${integerPart}${formattedMinutes}`
+}
+
 const PercentageCell: QueryContextColumnComponent = ({ value }) => {
     if (typeof value === 'number') {
         return <span>{`${(value * 100).toFixed(1)}%`}</span>
@@ -121,6 +138,11 @@ const BreakdownValueCell: QueryContextColumnComponent = (props) => {
                 )
             }
             break
+        case WebStatsBreakdown.Timezone:
+            if (typeof value === 'number') {
+                return <>{toUtcOffsetFormat(value)}</>
+            }
+            break
     }
 
     if (typeof value === 'string') {

posthog/hogql/functions/mapping.py

@@ -421,13 +421,15 @@ def compare_types(arg_types: list[ConstantType], sig_arg_types: tuple[ConstantTy
     "toString": HogQLFunctionMeta(
         "toString",
         1,
-        1,
+        2,
         signatures=[
             ((IntegerType(),), StringType()),
             ((StringType(),), StringType()),
             ((FloatType(),), StringType()),
             ((DateType(),), StringType()),
+            ((DateType(), StringType()), StringType()),
             ((DateTimeType(),), StringType()),
+            ((DateTimeType(), StringType()), StringType()),
         ],
     ),
     "toJSONString": HogQLFunctionMeta("toJSONString", 1, 1),

posthog/hogql_queries/web_analytics/stats_table.py

@@ -77,6 +77,7 @@ def to_main_query(self) -> ast.SelectQuery:
 )
 GROUP BY "context.columns.breakdown_value"
 ORDER BY "context.columns.visitors" DESC,
+"context.columns.views" DESC,
 "context.columns.breakdown_value" ASC
 """,
                 timings=self.timings,
@@ -118,6 +119,7 @@ def _to_main_query_with_session_properties(self) -> ast.SelectQuery:
 )
 GROUP BY "context.columns.breakdown_value"
 ORDER BY "context.columns.visitors" DESC,
+"context.columns.views" DESC,
 "context.columns.breakdown_value" ASC
 """,
                 timings=self.timings,
@@ -162,6 +164,7 @@ def to_entry_bounce_query(self) -> ast.SelectQuery:
 )
 GROUP BY "context.columns.breakdown_value"
 ORDER BY "context.columns.visitors" DESC,
+"context.columns.views" DESC,
 "context.columns.breakdown_value" ASC
 """,
                 timings=self.timings,
@@ -269,6 +272,7 @@ def to_path_scroll_bounce_query(self) -> ast.SelectQuery:
 ) AS scroll
 ON counts.breakdown_value = scroll.breakdown_value
 ORDER BY "context.columns.visitors" DESC,
+"context.columns.views" DESC,
 "context.columns.breakdown_value" ASC
 """,
                 timings=self.timings,
@@ -346,6 +350,7 @@ def to_path_bounce_query(self) -> ast.SelectQuery:
 ) as bounce
 ON counts.breakdown_value = bounce.breakdown_value
 ORDER BY "context.columns.visitors" DESC,
+"context.columns.views" DESC,
 "context.columns.breakdown_value" ASC
 """,
                 timings=self.timings,
@@ -500,9 +505,11 @@ def _counts_breakdown_value(self):
             case WebStatsBreakdown.CITY:
                 return parse_expr("tuple(properties.$geoip_country_code, properties.$geoip_city_name)")
             case WebStatsBreakdown.TIMEZONE:
-                # Timezone offsets would be slightly more useful, but that's not easily achievable
-                # with Clickhouse, we might attempt to change this in the future
-                return ast.Field(chain=["properties", "$timezone"])
+                # Get the difference between the UNIX timestamp at UTC and the UNIX timestamp at the event's timezone
+                # Value is in milliseconds, turn it to hours, works even for fractional timezone offsets (I'm looking at you, Australia)
+                return parse_expr(
+                    "if(or(isNull(properties.$timezone), empty(properties.$timezone)), NULL, (toUnixTimestamp64Milli(parseDateTimeBestEffort(assumeNotNull(toString(timestamp, properties.$timezone)))) - toUnixTimestamp64Milli(timestamp)) / 3600000)"
+                )
             case _:
                 raise NotImplementedError("Breakdown not implemented")
 

posthog/hogql_queries/web_analytics/test/test_web_stats_table.py

@@ -1006,50 +1006,142 @@ def test_cohort_test_filters(self):
         assert results == [["/path1", 1, 1]]
 
     def test_timezone_filter(self):
-        d1, s1 = "d1", str(uuid7("2024-07-30"))
-        d2, s2 = "d2", str(uuid7("2024-07-30"))
+        date = "2024-07-30"
+
+        for idx, (distinct_id, session_id) in enumerate(
+            [
+                ("UTC", str(uuid7(date))),
+                ("Asia/Calcutta", str(uuid7(date))),
+                ("America/New_York", str(uuid7(date))),
+                ("America/Sao_Paulo", str(uuid7(date))),
+            ]
+        ):
+            _create_person(
+                team_id=self.team.pk,
+                distinct_ids=[distinct_id],
+                properties={"name": session_id, "email": f"{distinct_id}@example.com"},
+            )
+
+            for i in range(idx + 1):
+                _create_event(
+                    team=self.team,
+                    event="$pageview",
+                    distinct_id=distinct_id,
+                    timestamp=date,
+                    properties={"$session_id": session_id, "$pathname": f"/path{i}", "$timezone": distinct_id},
+                )
+
+        results = self._run_web_stats_table_query(
+            "all",
+            None,
+            breakdown_by=WebStatsBreakdown.TIMEZONE,
+        ).results
+
+        # Brasilia UTC-3, New York UTC-4, Calcutta UTC+5:30, UTC
+        assert results == [[-3.0, 1.0, 4.0], [-4.0, 1.0, 3.0], [5.5, 1.0, 2.0], [0.0, 1.0, 1.0]]
+
+    def test_timezone_filter_dst_change(self):
+        did = "id"
+        sid = str(uuid7("2019-02-17"))
 
         _create_person(
             team_id=self.team.pk,
-            distinct_ids=[d1],
-            properties={"name": d1, "email": "[email protected]"},
+            distinct_ids=[did],
+            properties={"name": sid, "email": f"[email protected]"},
+        )
+
+        # Cross daylight savings time change in Brazil
+        for i in range(6):
+            _create_event(
+                team=self.team,
+                event="$pageview",
+                distinct_id=did,
+                timestamp=f"2019-02-17 0{i}:00:00",
+                properties={"$session_id": sid, "$pathname": f"/path1", "$timezone": "America/Sao_Paulo"},
+            )
+
+        results = self._run_web_stats_table_query(
+            "all",
+            None,
+            breakdown_by=WebStatsBreakdown.TIMEZONE,
+        ).results
+
+        # Change from UTC-2 to UTC-3 in the middle of the night
+        assert results == [[-3.0, 1.0, 4.0], [-2.0, 1.0, 2.0]]
+
+    def test_timezone_filter_with_invalid_timezone(self):
+        date = "2024-07-30"
+
+        for idx, (distinct_id, session_id) in enumerate(
+            [
+                ("UTC", str(uuid7(date))),
+                ("Timezone_not_exists", str(uuid7(date))),
+            ]
+        ):
+            _create_person(
+                team_id=self.team.pk,
+                distinct_ids=[distinct_id],
+                properties={"name": session_id, "email": f"{distinct_id}@example.com"},
+            )
+
+            for i in range(idx + 1):
+                _create_event(
+                    team=self.team,
+                    event="$pageview",
+                    distinct_id=distinct_id,
+                    timestamp=date,
+                    properties={"$session_id": session_id, "$pathname": f"/path{i}", "$timezone": distinct_id},
+                )
+
+        with self.assertRaisesRegex(Exception, "Cannot load time zone"):
+            self._run_web_stats_table_query(
+                "all",
+                None,
+                breakdown_by=WebStatsBreakdown.TIMEZONE,
+            )
+
+    def test_timezone_filter_with_empty_timezone(self):
+        did = "id"
+        sid = str(uuid7("2019-02-17"))
+
+        _create_person(
+            team_id=self.team.pk,
+            distinct_ids=[did],
+            properties={"name": sid, "email": f"[email protected]"},
         )
 
+        # Key not exists
         _create_event(
             team=self.team,
             event="$pageview",
-            distinct_id=d1,
-            timestamp="2024-07-30",
-            properties={"$session_id": s1, "$pathname": "/path1", "$timezone": "America/New_York"},
+            distinct_id=did,
+            timestamp=f"2019-02-17 00:00:00",
+            properties={"$session_id": sid, "$pathname": f"/path1"},
         )
 
-        _create_person(
-            team_id=self.team.pk,
-            distinct_ids=[d2],
-            properties={"name": d2, "email": "[email protected]"},
-        )
+        # Key exists, it's null
         _create_event(
             team=self.team,
             event="$pageview",
-            distinct_id=d2,
-            timestamp="2024-07-30",
-            properties={"$session_id": s2, "$pathname": "/path2", "$timezone": "America/Brasilia"},
+            distinct_id=did,
+            timestamp=f"2019-02-17 00:00:00",
+            properties={"$session_id": sid, "$pathname": f"/path1", "$timezone": None},
         )
+
+        # Key exists, it's empty string
         _create_event(
             team=self.team,
             event="$pageview",
-            distinct_id=d2,
-            timestamp="2024-07-30",
-            properties={"$session_id": s2, "$pathname": "/path3", "$timezone": "America/Brasilia"},
+            distinct_id=did,
+            timestamp=f"2019-02-17 00:00:00",
+            properties={"$session_id": sid, "$pathname": f"/path1", "$timezone": ""},
         )
 
-        flush_persons_and_events()
-
         results = self._run_web_stats_table_query(
             "all",
             None,
             breakdown_by=WebStatsBreakdown.TIMEZONE,
-            filter_test_accounts=True,
         ).results
 
-        assert results == [["America/Brasilia", 1.0, 2.0], ["America/New_York", 1.0, 1.0]]
+        # Don't crash, treat all of them null
+        assert results == []