Create a table sink for row-group or partitioned outputs

A table sink supports variable-sized outputs without returning large data.frames to the master. Each shard writes a separate row-group file.

Usage

table_sink(
  schema,
  mode = c("row_groups", "partitioned"),
  path = NULL,
  format = c("auto", "rds", "native")
)

schema: A shard_schema. If NULL, a schema-less sink is created (RDS format only). This is primarily intended for doShard/foreach compatibility where output schemas may not be known in advance.
mode: "row_groups" (temp, managed) or "partitioned" (persistent path).
path: Directory to write row-group files. If NULL, a temp dir is created.
format: Storage format for partitions: "rds" (data.frame RDS), "native" (columnar encoding with string offsets+bytes), or "auto" (selects "native" if the schema contains string_col(); otherwise "rds").

A shard_table_sink object.

v1.1 implementation notes:

Storage format is per-shard RDS (portable, CRAN-friendly).
This guarantees bounded master memory during execution; final collection may still be large if you materialize.

# \donttest{
s <- schema(x = float64(), label = string_col())
sink <- table_sink(s, mode = "row_groups")
# }