fix cutom events charts (#134)

Author: harshitsaamu

packages/db/src/services/chart.service.ts

@@ -600,11 +600,14 @@ export async function getChartSql({
       return buildInlineCohortJoin(cohortId, projectId, 'e', cohortMeta);
     }).join(' ');
 
+    // Determine data source: use custom event CTE if present, otherwise events table
+    const dataSource = customEvent ? 'custom_event_data' : TABLE_NAMES.events;
+
     // Add top_breakdowns CTE using the builder
     addCte(
       'top_breakdowns',
       `SELECT ${breakdownSelects}
-      FROM ${TABLE_NAMES.events} e
+      FROM ${dataSource} AS e
       ${profilesJoinRef ? `${profilesJoinRef} ` : ''}${cohortJoinsForTop ? `${cohortJoinsForTop} ` : ''}${getWhereWithoutBar()}
       GROUP BY ${breakdownSelects}
       ORDER BY count(*) DESC
@@ -685,19 +688,22 @@ export async function getChartSql({
 
     const totalCountWhere = getWhereWithoutBar();
 
+    // Determine data source: use custom event CTE if present, otherwise events table
+    const dataSourceForBreakdown = customEvent ? 'custom_event_data' : TABLE_NAMES.events;
+
     // Build cohort JOINs for breakdown_totals CTE
     // NOTE: ClickHouse CTEs cannot reference other CTEs in JOINs, so we inline the subquery
     const cohortJoinsForBreakdown = cohortIds.map((cohortId) => {
       const cohortMeta = cohortMetadata.get(cohortId);
-      return buildInlineCohortJoin(cohortId, projectId, TABLE_NAMES.events, cohortMeta);
+      return buildInlineCohortJoin(cohortId, projectId, dataSourceForBreakdown, cohortMeta);
     }).join(' ');
 
     addCte(
       'breakdown_totals',
       `SELECT
         ${breakdownSelects},
-        uniq(${TABLE_NAMES.events}.profile_id) as total_count
-       FROM ${TABLE_NAMES.events}
+        uniq(${dataSourceForBreakdown}.profile_id) as total_count
+       FROM ${dataSourceForBreakdown}
        ${profilesJoinRefForCTE ? `${profilesJoinRefForCTE} ` : ''}${cohortJoinsForBreakdown ? `${cohortJoinsForBreakdown} ` : ''}${totalCountWhere}
        GROUP BY ${breakdownGroupBy}`,
     );
@@ -714,17 +720,20 @@ export async function getChartSql({
   } else {
     const totalCountWhere = getWhereWithoutBar();
 
+    // Determine data source: use custom event CTE if present, otherwise events table
+    const dataSourceForTotal = customEvent ? 'custom_event_data' : TABLE_NAMES.events;
+
     // Build cohort JOINs for total_unique CTE
     // NOTE: ClickHouse CTEs cannot reference other CTEs in JOINs, so we inline the subquery
     const cohortJoinsForTotal = cohortIds.map((cohortId) => {
       const cohortMeta = cohortMetadata.get(cohortId);
-      return buildInlineCohortJoin(cohortId, projectId, TABLE_NAMES.events, cohortMeta);
+      return buildInlineCohortJoin(cohortId, projectId, dataSourceForTotal, cohortMeta);
     }).join(' ');
 
     addCte(
       'total_unique',
-      `SELECT uniq(${TABLE_NAMES.events}.profile_id) as total_count
-       FROM ${TABLE_NAMES.events}
+      `SELECT uniq(${dataSourceForTotal}.profile_id) as total_count
+       FROM ${dataSourceForTotal}
        ${profilesJoinRefForCTE ? `${profilesJoinRefForCTE} ` : ''}${cohortJoinsForTotal ? `${cohortJoinsForTotal} ` : ''}${totalCountWhere}`,
     );
 

packages/db/src/services/conversion.service.ts

@@ -159,7 +159,7 @@ export class ConversionService {
     // Build funnel conditions for all events
     const conditions = events.map(event => {
       const where = Object.values(
-        getEventFiltersWhereClause(event.filters),
+        getEventFiltersWhereClause(event.filters, projectId),
       ).join(' AND ');
 
       return where

packages/db/src/services/custom-event.service.ts

@@ -64,8 +64,17 @@ function buildCustomEventSourceQuery(
 }
 
 /**
- * Expand a custom event into SQL UNION of source events
- * This creates a CTE that can be used in place of the events table
+ * Expand a custom event into SQL query
+ *
+ * PERFORMANCE OPTIMIZATION:
+ * When all source events have no filters, we use a single SELECT with IN clause
+ * instead of UNION ALL. This reduces N table scans to 1 table scan.
+ *
+ * Example:
+ * - Before: 20 separate SELECTs with UNION ALL (20 table scans)
+ * - After: 1 SELECT with IN ('event1', 'event2', ..., 'event20') (1 table scan)
+ *
+ * For events with filters, we fall back to UNION ALL to ensure correct filtering.
  *
  * @param customEvent - The custom event definition
  * @param baseWhere - Base WHERE conditions to apply to all source events (date ranges, etc)
@@ -81,6 +90,33 @@ export function expandCustomEventToSQL(
 ): string {
   const definition = customEvent.definition;
 
+  // Check if we can use the optimized path
+  // Optimization is only safe when all events have no filters
+  const canOptimize = definition.events.every(
+    (event) => !event.filters || event.filters.length === 0
+  );
+
+  if (canOptimize && definition.events.length > 0) {
+    // OPTIMIZED PATH: Single SELECT with IN clause
+    // This reduces N table scans to 1 table scan, dramatically improving performance
+    const eventNames = definition.events.map((e) => sqlstring.escape(e.name));
+
+    const whereClauses = [
+      `project_id = ${sqlstring.escape(customEvent.projectId)}`,
+      `name IN (${eventNames.join(', ')})`,
+      ...baseWhere,
+    ];
+
+    return `
+      SELECT * REPLACE(${sqlstring.escape(customEvent.name)} AS name)
+      FROM ${TABLE_NAMES.events}
+      WHERE ${whereClauses.join(' AND ')}
+    `;
+  }
+
+  // FALLBACK PATH: UNION ALL for events with filters
+  // When events have filters, each event may need different WHERE conditions,
+  // so we must use UNION ALL to apply filters correctly per event
   const sourceQueries = definition.events.map((sourceEvent) =>
     buildCustomEventSourceQuery(
       customEvent.projectId,
@@ -90,6 +126,5 @@ export function expandCustomEventToSQL(
     ),
   );
 
-  // UNION ALL for OR logic (match any source event)
   return sourceQueries.join(' UNION ALL ');
 }

packages/db/src/services/funnel.service.ts

@@ -113,10 +113,10 @@ export class FunnelService {
     };
   }
 
-  getFunnelConditions(events: IChartEvent[] = []): string[] {
+  getFunnelConditions(events: IChartEvent[] = [], projectId?: string): string[] {
     return events.map((event) => {
       const { sb, getWhere } = createSqlBuilder();
-      sb.where = getEventFiltersWhereClause(event.filters);
+      sb.where = getEventFiltersWhereClause(event.filters, projectId);
       sb.where.name = `name = ${sqlstring.escape(event.name)}`;
       return getWhere().replace('WHERE ', '');
     });
@@ -147,7 +147,7 @@ export class FunnelService {
     fromClause: string;
     needsNameFilter: boolean;
   }) {
-    const funnels = this.getFunnelConditions(eventSeries);
+    const funnels = this.getFunnelConditions(eventSeries, projectId);
 
     const query = clix(this.client, timezone)
       .select([