From 05d56105fa980cae2728eed0057f5306a38ad6ce Mon Sep 17 00:00:00 2001
From: Brett Hoerner <brett@posthog.com>
Date: Wed, 4 Oct 2023 07:08:57 -0600
Subject: [PATCH] =?UTF-8?q?chore(plugin-server):=20add=20metrics=20trackin?=
 =?UTF-8?q?g=20merge=20txn=20attempt=20and=20succ=E2=80=A6=20(#17746)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

chore(plugin-server): add metrics tracking merge txn attempt and success rate
---
 .../src/worker/ingestion/person-state.ts      | 70 +++++++++++++------
 1 file changed, 47 insertions(+), 23 deletions(-)

diff --git a/plugin-server/src/worker/ingestion/person-state.ts b/plugin-server/src/worker/ingestion/person-state.ts
index 16cae0d5e1a1e..2bbd3bb4dd2dd 100644
--- a/plugin-server/src/worker/ingestion/person-state.ts
+++ b/plugin-server/src/worker/ingestion/person-state.ts
@@ -23,6 +23,16 @@ export const mergeFinalFailuresCounter = new Counter({
     help: 'Number of person merge final failures.',
 })
 
+export const mergeTxnAttemptCounter = new Counter({
+    name: 'person_merge_txn_attempt_total',
+    help: 'Number of person merge attempts.',
+})
+
+export const mergeTxnSuccessCounter = new Counter({
+    name: 'person_merge_txn_success_total',
+    help: 'Number of person merges that succeeded.',
+})
+
 // used to prevent identify from being used with generic IDs
 // that we can safely assume stem from a bug or mistake
 // used to prevent identify from being used with generic IDs
@@ -462,35 +472,49 @@ export class PersonState {
         createdAt: DateTime,
         properties: Properties
     ): Promise<[ProducerRecord[], Person]> {
-        return await this.db.postgres.transaction(PostgresUse.COMMON_WRITE, 'mergePeople', async (tx) => {
-            const [person, updatePersonMessages] = await this.db.updatePersonDeprecated(
-                mergeInto,
-                {
-                    created_at: createdAt,
-                    properties: properties,
-                    is_identified: true,
-                },
-                tx
-            )
+        mergeTxnAttemptCounter.inc()
+
+        const result: [ProducerRecord[], Person] = await this.db.postgres.transaction(
+            PostgresUse.COMMON_WRITE,
+            'mergePeople',
+            async (tx) => {
+                const [person, updatePersonMessages] = await this.db.updatePersonDeprecated(
+                    mergeInto,
+                    {
+                        created_at: createdAt,
+                        properties: properties,
+                        is_identified: true,
+                    },
+                    tx
+                )
+
+                // Merge the distinct IDs
+                // TODO: Doesn't this table need to add updates to CH too?
+                await this.handleTablesDependingOnPersonID(otherPerson, mergeInto, tx)
 
-            // Merge the distinct IDs
-            // TODO: Doesn't this table need to add updates to CH too?
-            await this.handleTablesDependingOnPersonID(otherPerson, mergeInto, tx)
+                const distinctIdMessages = await this.db.moveDistinctIds(otherPerson, mergeInto, tx)
 
-            const distinctIdMessages = await this.db.moveDistinctIds(otherPerson, mergeInto, tx)
+                const deletePersonMessages = await this.db.deletePerson(otherPerson, tx)
 
-            const deletePersonMessages = await this.db.deletePerson(otherPerson, tx)
+                let personOverrideMessages: ProducerRecord[] = []
+                if (this.poEEmbraceJoin) {
+                    personOverrideMessages = [await this.addPersonOverride(otherPerson, mergeInto, tx)]
+                }
 
-            let personOverrideMessages: ProducerRecord[] = []
-            if (this.poEEmbraceJoin) {
-                personOverrideMessages = [await this.addPersonOverride(otherPerson, mergeInto, tx)]
+                return [
+                    [
+                        ...personOverrideMessages,
+                        ...updatePersonMessages,
+                        ...distinctIdMessages,
+                        ...deletePersonMessages,
+                    ],
+                    person,
+                ]
             }
+        )
 
-            return [
-                [...personOverrideMessages, ...updatePersonMessages, ...distinctIdMessages, ...deletePersonMessages],
-                person,
-            ]
-        })
+        mergeTxnSuccessCounter.inc()
+        return result
     }
 
     private async addPersonOverride(