feat: add insightsWarehouseFilterParams function to fetch distinct event parameters

Author: moonrailgun

src/server/model/insights/warehouse.ts

@@ -440,3 +440,31 @@ LIMIT 100;`);
 
   return compact(rows.map((row) => get(row, 'event_name', '')));
 }
+
+export async function insightsWarehouseFilterParams(
+  applicationId: string
+): Promise<string[]> {
+  const connection = getWarehouseConnection();
+  const eventParametersTable = getWarehouseApplications().find(
+    (app) => app.name === applicationId
+  )?.eventParametersTable;
+
+  if (!eventParametersTable) {
+    throw new Error(`Event table not found for application ${applicationId}`);
+  }
+
+  const [rows] = await connection.query(`
+SELECT DISTINCT param_value
+FROM (
+    SELECT \`${eventParametersTable.paramsNameField}\` as param_value, \`${eventParametersTable.dateBasedCreatedAtField ?? eventParametersTable.createdAtField}\` as date
+    FROM \`${eventParametersTable.name}\`
+    ORDER BY \`${eventParametersTable.dateBasedCreatedAtField ?? eventParametersTable.createdAtField}\` DESC
+) t
+LIMIT 100;`);
+
+  if (!Array.isArray(rows)) {
+    throw new Error(`Invalid rows from warehouse`);
+  }
+
+  return compact(rows.map((row) => get(row, 'param_value', '')));
+}

src/server/trpc/routers/insights.ts

@@ -14,6 +14,7 @@ import { uniq } from 'lodash-es';
 import {
   getWarehouseApplications,
   insightsWarehouseEvents,
+  insightsWarehouseFilterParams,
 } from '../../model/insights/warehouse.js';
 
 export const insightsRouter = router({
@@ -139,6 +140,13 @@ export const insightsRouter = router({
         }));
 
         return [...payloadFields, ...builtinFields];
+      } else if (insightType === 'warehouse') {
+        const params = await insightsWarehouseFilterParams(insightId);
+        return params.map((item) => ({
+          name: item,
+          type: 'string',
+          count: 0,
+        }));
       }
 
       return [];