Struct ColumnWrite 

pub struct ColumnWrite { /* private fields */ }

Values for new nullable fields over the rows of one exact version of a table, from Table::column_writer, which join its schema in its next version.

Values cover every row of a fragment with Self::attach_columns or chosen rows with Self::patch_rows; rows without values read NULL. Either way the values go into new files beside the fragment’s existing ones, which are never rewritten. ColumnWrite::finish returns the table’s next version, which is published only once a Commit stages it and publishes.

Implementations

impl ColumnWrite

pub fn source(&self) -> &Table

The exact source version whose rows the values cover.

pub fn fields(&self) -> SchemaRef

The fields this write gives values for.

pub async fn attach_columns( &mut self, fragment_id: Uuid, values: impl IntoArrowStream, ) -> Result<(), Error>

Attach values of every field to fragment fragment_id of the source: one stream of batches with a value for every row the fragment keeps, in stored order, which is the order a scan of the fragment’s splits returns. The values are written as they arrive, into new files attached to the fragment in the next version; the fragment’s existing files are left as they are. Rows the source deletes read NULL. A write attaches each fragment once, and not to rows it also patches: ColumnWrite::finish refuses both.

pub async fn patch_rows( &mut self, rows: impl IntoArrowStream, ) -> Result<(), Error>

Write values for some rows, recorded beside their fragments: each row names its target in a ROW_ID_COLUMN column, and its other columns are some of Self::fields.

pub async fn finish(self) -> Result<Table, Error>

Prepare the table’s next version, with the new columns and every value written, and register it.