Bet Latency Percentiles by Region

Write a query to compute percentiles of bet placement latency across different geographical regions using advanced aggregation functions.

Use the provided region and bet placement data. Ignore placements whose latency is NULL, but retain regions with no valid latency measurements.

Output

1. One row per region, including regions without valid measurements.
2. Columns: region_id, region_name, p50_latency_ms, p90_latency_ms, and p95_latency_ms.
3. Sort by region_name ascending, then region_id ascending.