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Set partitioning keys for a table

Source: R/partitioning.R
set_table_partitioning.Rd

Declares how newly written data files for a table should be split up. Partitioning lets DuckLake prune files during query planning, which can speed up filtered reads on large tables considerably.

Usage

set_table_partitioning(table_name, partition_by)

Arguments

table_name

The name of the table to partition.

partition_by

Character vector of partition expressions. Each entry must be one of:

  • a column name, e.g. "region" (identity transform)

  • "year(col)", "month(col)", "day(col)", or "hour(col)" for timestamp columns

  • "bucket(n, col)" for hash bucketing into n buckets

Value

Invisibly returns NULL.

Details

Partitioning only affects data written after the keys are set; previously written files keep their layout. To re-partition existing data, rewrite the table (e.g. with replace_table()) after setting the keys.

Runs ALTER TABLE ... SET PARTITIONED BY (...). The expressions are validated against the transforms DuckLake supports before any SQL is built.

See also

reset_table_partitioning(), get_table_partitions()

Other partitioning: get_table_partitions(), reset_table_partitioning()

Examples

if (FALSE) { # \dontrun{
# Partition new files by year and month of the event timestamp
set_table_partitioning("events", c("year(event_time)", "month(event_time)"))

# Plain column partitioning
set_table_partitioning("sales", "region")

# Hash user ids into 8 buckets, then split by month
set_table_partitioning("visits", c("bucket(8, user_id)", "month(ts)"))
} # }