Summary

PostgreSQL clients treat ParameterStatus message names as case-sensitive and expect canonical capitalization for certain parameters.
Three parameters in PostgreSQL use capitalized names instead of lowercase for historical reasons:

• DateStyle
• TimeZone
• IntervalStyle

These parameters predate the unified GUC (Grand Unified Configuration) system and retained their mixed-case names for backward compatibility.
Because ProxySQL previously sent them as datestyle, timezone, and intervalstyle, some PostgreSQL clients failed to recognize them and ignored their values.

Fix

• Updated ProxySQL to send canonical capitalization for DateStyle, TimeZone, and IntervalStyle.
• All other ParameterStatus keys continue to use lowercase names, consistent with PostgreSQL.