Hey team, 👋 here is the Pinot team at Slack with the question about the safety Upsert table at ~40% Old Gen with 0 old-gen GC We're running Pinot 1.4.0 with a FULL-upsert realtime table (~1.2B PKs, MURMUR3, 2d retention, 24 servers,

-Xmx 38G

,

-XX:InitiatingHeapOccupancyPercent=25

). After tuning (retention reduction, Xmx increase, instance spread), Old Gen sits at 38–44% depending on the PK sawtooth phase. The PK map is 98% of heap (

jmap -histo:live

verified, 206 bytes/entry). We see zero old-gen GC events, 0 query failures, and P50 180ms across 7,200-query benchmarks. However, @Mayank also provided the guideline recommending Old Gen <30% of Xmx for upsert tables or max heap < 70% of Xmx . So we want to double check if one of the following condition a safe steady state for production 1. ~45% Old Gen with 0 old-gen GC 2. max heap < 70% most of time but some seldom random spike to > 80%

This seems fine:

1. ~45% Old Gen with 0 old-gen GC

2. max heap < 70% most of time but some seldom random spike to > 80%

@Mayank thank you so much for the quick respond and the confirmation above thanks then we will release with the curr status and keep updating the stability with this configuration cc: @Neeraja Sridharan