feat(hogql): better debug errors (#18522)

PostHog · Nov 9, 2023 · 7cf0229 · 7cf0229
1 parent bc55393
commit 7cf0229
Show file tree

Hide file tree

Showing 6 changed files with 73 additions and 20 deletions.
diff --git a/frontend/src/queries/schema.json b/frontend/src/queries/schema.json
@@ -1541,38 +1541,51 @@
             "additionalProperties": false,
             "properties": {
                 "clickhouse": {
+                    "description": "Executed ClickHouse query",
                     "type": "string"
                 },
                 "columns": {
+                    "description": "Returned columns",
                     "items": {},
                     "type": "array"
                 },
+                "error": {
+                    "description": "Query error. Returned only if 'explain' is true. Throws an error otherwise.",
+                    "type": "string"
+                },
                 "explain": {
+                    "description": "Query explanation output",
                     "items": {
                         "type": "string"
                     },
                     "type": "array"
                 },
                 "hogql": {
+                    "description": "Generated HogQL query",
                     "type": "string"
                 },
                 "modifiers": {
-                    "$ref": "#/definitions/HogQLQueryModifiers"
+                    "$ref": "#/definitions/HogQLQueryModifiers",
+                    "description": "Modifiers used when performing the query"
                 },
                 "query": {
+                    "description": "Input query string",
                     "type": "string"
                 },
                 "results": {
+                    "description": "Query results",
                     "items": {},
                     "type": "array"
                 },
                 "timings": {
+                    "description": "Measured timings for different parts of the query generation process",
                     "items": {
                         "$ref": "#/definitions/QueryTiming"
                     },
                     "type": "array"
                 },
                 "types": {
+                    "description": "Types of returned columns",
                     "items": {},
                     "type": "array"
                 }

diff --git a/frontend/src/queries/schema.ts b/frontend/src/queries/schema.ts
@@ -139,14 +139,25 @@ export interface HogQLQueryModifiers {
 }
 
 export interface HogQLQueryResponse {
+    /** Input query string */
     query?: string
+    /** Generated HogQL query */
     hogql?: string
+    /** Executed ClickHouse query */
     clickhouse?: string
+    /** Query results */
     results?: any[]
-    types?: any[]
+    /** Query error. Returned only if 'explain' is true. Throws an error otherwise. */
+    error?: string
+    /** Returned columns */
     columns?: any[]
+    /** Types of returned columns */
+    types?: any[]
+    /** Measured timings for different parts of the query generation process */
     timings?: QueryTiming[]
+    /** Query explanation output */
     explain?: string[]
+    /** Modifiers used when performing the query */
     modifiers?: HogQLQueryModifiers
 }
 

diff --git a/frontend/src/scenes/debug/HogQLDebug.tsx b/frontend/src/scenes/debug/HogQLDebug.tsx
@@ -91,6 +91,14 @@ export function HogQLDebug({ query, setQuery, queryKey }: HogQLDebugProps): JSX.
                     </>
                 ) : (
                     <>
+                        {response?.error ? (
+                            <>
+                                <h2 className="text-danger">Error Running Query!</h2>
+                                <CodeSnippet language={Language.Text} wrap>
+                                    {response.error}
+                                </CodeSnippet>
+                            </>
+                        ) : null}
                         {response?.hogql ? (
                             <>
                                 <h2>Executed HogQL</h2>

diff --git a/posthog/hogql/query.py b/posthog/hogql/query.py
@@ -1,6 +1,7 @@
 from typing import Dict, Optional, Union, cast
 
 from posthog.clickhouse.client.connection import Workload
+from posthog.errors import ExposedCHQueryError
 from posthog.hogql import ast
 from posthog.hogql.constants import HogQLGlobalSettings
 from posthog.hogql.errors import HogQLException
@@ -143,16 +144,27 @@ def execute_hogql_query(
             timings=timings_dict,
         )
 
-        results, types = sync_execute(
-            clickhouse_sql,
-            clickhouse_context.values,
-            with_column_types=True,
-            workload=workload,
-            team_id=team.pk,
-            readonly=True,
-        )
+        error = None
+        try:
+            results, types = sync_execute(
+                clickhouse_sql,
+                clickhouse_context.values,
+                with_column_types=True,
+                workload=workload,
+                team_id=team.pk,
+                readonly=True,
+            )
+        except Exception as e:
+            if explain:
+                results, types = None, None
+                if isinstance(e, ExposedCHQueryError) or isinstance(e, HogQLException):
+                    error = str(e)
+                else:
+                    error = "Unknown error"
+            else:
+                raise e
 
-    if explain:
+    if explain and error is None:  # If the query errored, explain will fail as well.
         with timings.measure("explain"):
             explain_results = sync_execute(
                 f"EXPLAIN {clickhouse_sql}",
@@ -170,6 +182,7 @@ def execute_hogql_query(
         query=query,
         hogql=hogql,
         clickhouse=clickhouse_sql,
+        error=error,
         timings=timings.to_list(),
         results=results,
         columns=print_columns,

diff --git a/posthog/hogql_queries/hogql_query_runner.py b/posthog/hogql_queries/hogql_query_runner.py
@@ -65,6 +65,7 @@ def calculate(self) -> HogQLQueryResponse:
             workload=Workload.ONLINE,
             timings=self.timings,
             in_export_context=self.in_export_context,
+            explain=bool(self.query.explain),
         )
 
     def _is_stale(self, cached_result_package):

diff --git a/posthog/schema.py b/posthog/schema.py
@@ -830,15 +830,22 @@ class HogQLQueryResponse(BaseModel):
     model_config = ConfigDict(
         extra="forbid",
     )
-    clickhouse: Optional[str] = None
-    columns: Optional[List] = None
-    explain: Optional[List[str]] = None
-    hogql: Optional[str] = None
-    modifiers: Optional[HogQLQueryModifiers] = None
-    query: Optional[str] = None
-    results: Optional[List] = None
-    timings: Optional[List[QueryTiming]] = None
-    types: Optional[List] = None
+    clickhouse: Optional[str] = Field(default=None, description="Executed ClickHouse query")
+    columns: Optional[List] = Field(default=None, description="Returned columns")
+    error: Optional[str] = Field(
+        default=None, description="Query error. Returned only if 'explain' is true. Throws an error otherwise."
+    )
+    explain: Optional[List[str]] = Field(default=None, description="Query explanation output")
+    hogql: Optional[str] = Field(default=None, description="Generated HogQL query")
+    modifiers: Optional[HogQLQueryModifiers] = Field(
+        default=None, description="Modifiers used when performing the query"
+    )
+    query: Optional[str] = Field(default=None, description="Input query string")
+    results: Optional[List] = Field(default=None, description="Query results")
+    timings: Optional[List[QueryTiming]] = Field(
+        default=None, description="Measured timings for different parts of the query generation process"
+    )
+    types: Optional[List] = Field(default=None, description="Types of returned columns")
 
 
 class LifecycleFilter(BaseModel):