vectra (version 0.6.2)

create_index: Create a hash index on a .vtr file column

Description

Builds a persistent hash index stored as a .vtri sidecar file alongside the .vtr file. The index maps key hashes to row group indices, enabling O(1) row group identification for equality predicates (filter(col == value)).

Usage

create_index(path, column, ci = FALSE)

Value

Invisible NULL. The index is written as a .vtri sidecar file.

Arguments

path

Path to a .vtr file.

column

Character vector. Name(s) of column(s) to index.

ci

Logical. Build a case-insensitive index? Default FALSE.

Details

For composite indexes on multiple columns, pass a character vector. Composite indexes accelerate AND-combined equality predicates (e.g., filter(col1 == "a", col2 == "b")).

The index is automatically loaded by tbl() when present. It composes with zone-map pruning and binary search on sorted columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(data.frame(id = letters, val = 1:26, stringsAsFactors = FALSE), f)
create_index(f, "id")
tbl(f) |> filter(id == "m") |> collect()
unlink(c(f, paste0(f, ".id.vtri")))