ClickHouse Names a Part After Partition, Block Range, and Level: The Directory Name Is the Index
A MergeTree part’s directory name encodes its partition, block range and merge level, so parts can be listed and reasoned about without opening them.
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ClickHouse System Tables Are Storages, Not Views: A Column Mask Computes Only What You Select
System tables are ordinary storages whose source is rebuilt per query, with a column mask so only requested columns are computed.
BuzzHouse's Grammar Drifts: Probability Intervals Shift 10% Every 500 Draws
BuzzHouse’s query grammar uses bounded, drifting probability intervals plus depth/width budgets so the fuzzer keeps producing new query shapes instead of repeating itself.
ClickHouse's Client Parses a Script Instead of Splitting It: A Semicolon Can Be Data
The client parses a script statement by statement, ends inline INSERT data at a blank line, and pulls the trailing comment (and its test hint) into the statement it belongs to.
ClickHouse's Query Log Is a Real MergeTree Table: Created Lazily, Flushed Every 7.5 Seconds
The query log is an in-memory queue drained every 7.5 seconds by a background thread that INSERTs into a lazily created MergeTree table.