ChDriver.
Copy Markdown
Decoders for ClickHouse's wrapper and compound column types: Nullable(T),
Array(T), Map(K, V), LowCardinality(T), and Decimal(P, S).
Dispatched from ChDriver.Protocol.NativeBlock's decode_column_data/3,
which these functions recurse back into for their inner type(s) — that's
what lets deeply nested types like Array(Nullable(String)) or
Map(String, Array(UInt32)) decode correctly without any special-casing.
Map(K, V) values decode to plain Elixir maps; Array(T) and
LowCardinality(T) decode to lists; Nullable(T) decodes to the inner
value or nil; Decimal(P, S) decodes to a Decimal.t(). See
ARCHITECTURE.md for the wire-level byte layouts.
Summary
Functions
Splits values (the flattened element array) back into per-row lists
using Array(T)'s cumulative offsets, e.g. values = [1, 2, 3, 4, 5]
and offsets = [2, 2, 5] (row 0 has 2 elements, row 1 has 0, row 2 has