Compiled artifacts and exports#

parcel_runtime saves and loads compilations, exports validation plans, and represents stored column definitions.

`CompiledBytes`#

The trait is in parcel_runtime::compiled and is implemented by parcel_core::Compilation:

pub trait CompiledBytes: Sized {
    fn to_bytes(&self) -> Result<Vec<u8>, String>;
    fn from_bytes(bytes: &[u8]) -> Result<Self, String>;
}

Method	Arguments and result
`to_bytes`	Borrows a compilation and returns its serialized contract, validation plan, and write plan. Encoding errors return a string.
`from_bytes`	Reads the supplied bytes and returns the saved compilation without recompiling. Invalid data, format differences, or a different parcel version return an error.

compiled::FORMAT identifies the format, currently parcel-compiled/1. Import the trait to call these methods:

use parcel_core::Compilation;
use parcel_runtime::compiled::CompiledBytes;

fn round_trip(artifacts: &Compilation) -> Result<Compilation, String> {
    let bytes = artifacts.to_bytes()?;
    Compilation::from_bytes(&bytes)
}

SQL export#

pub fn validation_sql(
    c: &Compilation, dialect: &str, table: &str,
) -> Result<SqlExport, String>;

This function is in parcel_runtime::export. c supplies the validation plan, dialect selects the SQL syntax, and table names the data table in the receiving engine. Unsupported dialects or unrepresentable plans return an error.

export::DIALECTS lists the accepted names: datafusion, duckdb, postgres, mysql, sqlite, bigquery, and snowflake.

`SqlExport` fields#

Field	Type	Meaning
`dialect`	`String`	Selected dialect.
`sql`	`String`	Validation query text.
`warnings`	`Vec<String>`	Constructs whose behavior has not been verified for that dialect.

For an existing compilation:

let exported = parcel_runtime::export::validation_sql(&artifacts, "duckdb", "orders")?;
println!("{};", exported.sql);
for warning in exported.warnings {
    eprintln!("{warning}");
}

This exports quality validation, not the contract’s access policies or masking.

Substrait export#

pub fn validation_substrait(
    c: &Compilation, table: &str,
) -> Result<(Vec<u8>, Vec<String>), String>;

Also in parcel_runtime::export, available with the substrait feature. c supplies the validation plan and table names the receiving data table. The tuple contains protobuf plan bytes and warnings, in that order. Conversion failures return an error string.

Stored schema helpers#

These items are in parcel_runtime::compiled:

Item	Fields or signature	Meaning
`ColumnDef`	`name: String`, `data_type: String`, `nullable: bool`	Persisted Arrow column definition; `data_type` is serialized under the JSON key `type`.
`schema_to_defs`	`(schema: &Schema) -> Vec<ColumnDef>`	Converts an Arrow schema to stored definitions.
`schema_from_defs`	`(defs: &[ColumnDef]) -> Result<Schema, String>`	Restores the schema; invalid Arrow type strings return an error.
`BundledFunction`	`owner: String`, `manifest: FunctionManifest`, `module: String`	A module and its manifest; `module` contains hexadecimal bytes.
`session`	`() -> SessionContext`	Creates a session with parcel functions registered for decoding.

For loading and verifying function implementations, see WebAssembly runtime.