Documentation
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Overview ¶
Package rows compiles a per-shape encoder plan from a RowDescription and provides the hot row loop that writes JSON.
Index ¶
- func AppendArray(dst, body []byte, plan *Plan) ([]byte, error)
- func AppendObject(dst, body []byte, plan *Plan) ([]byte, error)
- func AppendTOONRow(dst, body []byte, plan *Plan) ([]byte, error)
- func PickResultFormats(cols []Column) []int16
- func PickResultFormatsEx(cols []Column, binaryNumeric bool) []int16
- type Column
- type Plan
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AppendArray ¶
AppendArray writes the row as a JSON array (used by columnar mode).
func AppendObject ¶
DataRow body layout:
int16 column count for each column: int32 length (-1 for NULL) bytes value (length bytes; absent if length == -1)
AppendObject decodes one DataRow body and appends a JSON object using the supplied plan. Returns the new dst.
The column read loop is hand-inlined: a helper would add one function frame per cell and force the slice header through memory on every call. The hot loop runs per DataRow and this is the single biggest cell-level win we can bank without SIMD. The only shared helper is the bounds guard; keep the decoding arithmetic here.
A plan-bytecode variant (inline switch on a per-column opcode) was prototyped and measured flat-to-slightly-negative on both the mixed micro-bench (49.3 ns/op vs 46.2 ns/op) and the live 100k-row shapes (-1 to -2% on covered shapes, within run-to-run noise). With a warm branch predictor the func-pointer Encoder is already close to free; the switch overhead did not pay back. Reverted. See git history if you want to re-explore with SIMD or per-shape codegen.
func AppendTOONRow ¶
AppendTOONRow decodes one DataRow and emits a TOON row:
val1,val2,...,valN\n
Values reuse the existing per-column Encoder because its JSON form already matches TOON's rules for the scalars we care about:
- numbers (int/float/numeric): bare decimal digits
- bool: literal true / false
- null: literal null
- strings, date/time, uuid: "..." with JSON escapes
- json / jsonb: emitted as raw JSON (object, array, string, number, bool, null). The TOON parser is expected to bracket-balance `{}` / `[]` and string-aware scan so an inner comma does not split a cell. This preserves the jsonb passthrough win.
Row terminator is '\n'. There is no trailing comma.
func PickResultFormats ¶
PickResultFormats returns one int16 per column describing the format we want the server to send (1=binary, 0=text), based on which OIDs have specialised binary encoders. Equivalent to PickResultFormatsEx(cols, false).
func PickResultFormatsEx ¶
PickResultFormatsEx is PickResultFormats with the BinaryNumeric toggle. When binaryNumeric is true, NUMERIC columns are requested in binary format.
Types ¶
type Column ¶
type Column struct {
Name string
TableOID uint32
AttrNum int16
TypeOID protocol.OID
TypeMod int32
TypeLen int16
Format int16
Encoder types.Encoder
KeyPrefix []byte // pre-built `"name":`
KeyPrefixComma []byte // pre-built `,"name":` for columns > 0
}
Column captures the parsed RowDescription field plus its compiled encoder.
type Plan ¶
type Plan struct {
Columns []Column
// ColumnsArrayHeader is the JSON header for the columnar mode:
// `{"columns":["a","b"],"rows":[`
ColumnsArrayHeader []byte
// TOONHeader is the header for the TOON streaming mode:
// `[?]{col1,col2,...}\n`. Streamed row count is unknown hence `?`.
TOONHeader []byte
}
Plan is the cached per-shape execution plan for a result set.
func ParseRowDescription ¶
ParseRowDescription reads a 'T' message body and returns a compiled Plan.
Body layout (server -> client):
int16 field count for each field: cstring name int32 table OID (0 if not from a table) int16 attribute number int32 type OID int16 type size int32 type modifier int16 format code
func ParseRowDescriptionForFormats ¶
ParseRowDescriptionForFormats parses a 'T' body and applies binary encoders for any column whose format code (in `formats`) is 1.
func (*Plan) ApplyFormats ¶
ApplyFormats rewrites the encoder for each column to match the supplied per-column format codes. Used after Bind asks the server for binary on some columns. Equivalent to ApplyFormatsEx(formats, false).
func (*Plan) ApplyFormatsEx ¶
ApplyFormatsEx is ApplyFormats with the BinaryNumeric toggle. When binaryNumeric is true, NUMERIC columns whose format is 1 pick up the binary decoder from numeric_bin.go.
Source Files