Read table, view, and column comments from a DuckLake catalog

Returns the current comments stored in the lake – via set_table_comment(), set_column_comments(), create_table()'s label sync, or any other client – as a tidy data frame.

Usage

get_table_comments(table_name = NULL, ducklake_name = NULL)

Arguments

table_name

Optional table (or view) name to filter to, optionally qualified as "schema.table"; a bare name matches that table in every schema.

ducklake_name

Optional name of the attached DuckLake catalog. If NULL, the current database is used.

Value

A data frame with one row per comment: object_type ("table", "view", or "column"), schema_name, table_name, column_name (NA for tables and views), and comment. Zero rows when nothing is commented.

Details

The comments are read through DuckDB's catalog functions, so they match what the session sees. On a lake attached with snapshot_version or snapshot_time they are the comments as of that snapshot, and inside an open transaction they include the ones it has set and not yet committed.

See also

get_metadata_table() for the raw ducklake_tag and ducklake_column_tag catalog tables, which keep every version of a comment.

Other table documentation: set_column_comments(), set_table_comment()

Examples

lake_dir <- tempfile("readcomment_lake_")
dir.create(lake_dir)
attach_ducklake("readcomment_lake", lake_path = lake_dir)
create_table(mtcars, "cars")
set_table_comment("cars", "Motor Trend road tests")
#> Commented table "cars".
set_column_comments("cars", mpg = "Miles per US gallon")
#> Commented 1 column on "cars".

# Everything documented in the lake
get_table_comments()
#>   object_type schema_name table_name column_name                comment
#> 1      column        main       cars         mpg    Miles per US gallon
#> 2       table        main       cars        <NA> Motor Trend road tests

# One table's documentation
get_table_comments("cars")
#>   object_type schema_name table_name column_name                comment
#> 1      column        main       cars         mpg    Miles per US gallon
#> 2       table        main       cars        <NA> Motor Trend road tests

detach_ducklake("readcomment_lake", shutdown = TRUE)
unlink(lake_dir, recursive = TRUE)