ClickHouse's Thread Pool Wakes the Newest Idle Thread and Counts Events Per CPU
ClickHouse’s thread pool wakes the most recently idle thread, and its counters are sharded per CPU so that counting never costs a cache-line ping-pong.
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ClickHouse's Token-Bucket Throttler Sleeps Without Burning a CPU Slot
ClickHouse’s throttler is a token bucket that sleeps for the token deficit and parks the caller’s CPU lease so the wait need not consume concurrency budget.
How ClickHouse Compresses Columns: Delta, Gorilla and the CODEC Pipeline
ClickHouse’s column codecs are bit-level transforms chained under a generic compressor: Delta, DoubleDelta and Gorilla, nested by CODEC(…).
How ClickHouse Deduplicates Retried Inserts with a Content Hash
ClickHouse hashes each inserted block into a UInt128 dedup token and keeps a bounded window of recent tokens to detect retries.
How ClickHouse Parses CSV in Parallel
ClickHouse splits CSV into row-aligned chunks with a quote-aware scanner, parses them on separate threads, and reorders them with a ticket ring.