API Reference ch_driver v#0.1.0

Public API for the ClickHouse native-protocol driver: a DBConnection pool wrapping ChDriver.Connection's TCP handshake and query encoding.

LZ4 block compression and CityHash v1.0.2 checksums for ClickHouse's native protocol block framing.

Socket-level connection setup and query execution for ClickHouse's native TCP protocol.

DBConnection behaviour implementation wrapping ChDriver.Connection's synchronous request/response socket so it can be used as a normal pooled connection.

Represents a DB::Exception (or DB::NetException) returned by the server in an Exception packet (Server packet type 2).

Turns an Elixir value into a ClickHouse query parameter: the declared {name:Type} type name, the unquoted/unescaped literal text, and the wire-level escaping depth that text needs.

ClickHouse native-protocol packet types relevant to the initial connection handshake.

Encodes and decodes ClickHouse native-protocol compressed block envelopes.

Decoders for ClickHouse's wrapper/compound column types, dispatched from ChDriver.Protocol.NativeBlock's decode_column_data/3: Nullable(T), Array(T), Map(K, V), LowCardinality(T), and Decimal(P, S). Nullable/Array/Map/LowCardinality each recurse back into ChDriver.Protocol.NativeBlock's decode_column_data/3 for their inner type(s) -- this mutual recursion across the module boundary is what makes arbitrarily nested types like Array(Nullable(String)) or Map(String, Array(UInt32)) work for free; see ChDriver.Protocol.NativeBlock's moduledoc for how new wrapper types should be added alongside these.

The initial packet sent by the client to open a connection.

Per-message byte layouts for the ClickHouse native protocol.

Decodes ClickHouse's plaintext "Native" block format -- the payload of a Data (or wire-identical ProfileEvents) packet once any compression envelope has been stripped away.

The server's response to ClientHello, describing itself.

LEB128-style unsigned varint encoding used throughout ClickHouse's native protocol for packet-type discriminants, lengths, revisions, and other small-to-medium unsigned integers.

A query for ChDriver.DBConnection -- a raw SQL string, optionally containing ? positional placeholders (rewritten by parse/2 into ClickHouse native {name:Type} parameter placeholders at execute time) or literal {name:Type} placeholders written directly by the caller.

The result of executing a ChDriver.Query, returned from DBConnection.execute/3,4 via ChDriver.query/2,3.

An Enumerable that lazily executes a query and yields its rows one ClickHouse wire-protocol Data block at a time, instead of buffering the whole result in memory the way ChDriver.query/2,3,4 does.

Parses ClickHouse's column type strings (e.g. "Nullable(String)", "Map(String, Decimal(10, 2))") into their component parts. Pure string parsing only -- no wire decoding happens here; see ChDriver.Types.Registry for the scalar codec table and ChDriver.Protocol.Block.Wrappers / ChDriver.Protocol.Block.Sparse for how these parsed types drive decoding of wrapper/compound column data.

The scalar/fixed-width type codec table (column_codec/1) plus the primitive wire readers it hands out: decode_fixed_width/4 (fixed-width binary chunks, one per row, each run through a per-type unpack function) and decode_strings/3 (ClickHouse's length-prefixed String encoding).