clickhouse

Overview ¶

Package clickhouse provides the ClickHouse database engine implementation.

ClickHouse is a column-oriented OLAP database. This engine:

• Uses a custom DDL preprocessor that strips the ClickHouse-specific ENGINE clause from CREATE TABLE statements, then delegates to the SQLite parser, which handles balanced-parenthesis type wrappers (Nullable(T), Array(T), Map(K,V)) as single column-type strings.

• Does NOT require a live ClickHouse connection for code generation. The reference Go driver is github.com/ClickHouse/clickhouse-go/v2 (pure Go), but no driver import is needed at code-generation time.

• Type wrappers are unwrapped at the type-mapper level, not the parser level. The parser preserves "Nullable(String)" as-is; the mapper resolves it.

Package clickhouse provides the ClickHouse database engine implementation.

Type-mapping notes:

• Int8/16/32/64 → int8/int16/int32/int64; UInt8/16/32/64 → uint8/.../uint64.
• Int128/256, UInt128/256 → string (no native Go integer type).
• Float32/64 → float32/float64.
• String, FixedString(N) → string.
• Bool/Boolean → bool.
• UUID → string (override via custom_types).
• Date, Date32, DateTime, DateTime64(...) → time.Time (requires "time").
• JSON → json.RawMessage (requires "encoding/json").
• Decimal(p,s), Decimal64(s) → string (safe lossless default).
• Enum8(...), Enum16(...) → string.
• Nullable(T) → unwrapped to T with nullable=true, so the usual sql.NullX / *T resolution applies.
• Array(T) → []<goT>. The element type may itself be wrapped, e.g. Array(Nullable(String)) → []sql.NullString or []*string.
• LowCardinality(T) → same as T (storage hint, not a Go-type change).
• Map(K,V) → map[goK]goV for simple base-type keys/values; falls back to json.RawMessage for complex value types (e.g. Array values).
• Unknown types fall back to any.