TLDR Tech / DevOps
Just One Function, 10x Faster? Reading a Rust Performance PR
GreptimeDB sped up Prometheus remote-read conversion by 4–16x by borrowing strings directly from Apache Arrow arrays instead of materializing every label value and by moving allocations from every row to every unique time series. The optimization eliminated repeated string copies, unnecessary heap allocations, and costly dictionary expansion in a CPU-heavy conversion path that previously processed only about 2 million rows per second.
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