Row layout for fixed-row table outputs

Computes disjoint row ranges for each shard via prefix-sum, enabling lock-free writes where each shard writes to a unique region.

Usage

row_layout(shards, rows_per_shard)

Arguments

shards

A shard_descriptor.

rows_per_shard

Either a scalar integer or a function(shard)->integer.

Value

A named list mapping shard id (character) to an idx_range(start, end).

Examples

# \donttest{
sh <- shards(100, block_size = 25)
layout <- row_layout(sh, rows_per_shard = 25L)
# }