Enforce Column Types Before Export — enforce_column

Runs ALTER TABLE ... ALTER COLUMN ... TYPE for every column whose current DuckDB type differs from the target type. Intended to run right before write_parquet_outputs() so that parquet files carry correct integer/decimal types instead of DOUBLE from R's default numeric mapping.

Usage

enforce_column_types(
  con,
  d_flds_rd = NULL,
  type_overrides = NULL,
  tables = NULL,
  verbose = TRUE
)

Arguments

con: DuckDB connection
d_flds_rd: Field redefinition data frame with columns tbl_new, fld_new, type_new (optional; NULL skips this source)
type_overrides: Named list of table.column = "SQL_TYPE" overrides for derived-table columns (optional; NULL skips)
tables: Character vector of tables to enforce. If NULL, uses all tables from DBI::dbListTables(con).
verbose: Print messages for each change (default: TRUE)

Value

Tibble of changes applied (table, column, from_type, to_type, success)

Details

Target types come from two sources:

d_flds_rd (field redefinition data frame) — keyed by tbl_new.fld_new with target in type_new
type_overrides — named list for derived-table columns not in the redefinition file, e.g. list(ichthyo.species_id = "SMALLINT")

Examples

if (FALSE) { # \dontrun{
changes <- enforce_column_types(
  con            = con,
  d_flds_rd      = d$d_flds_rd,
  type_overrides = list(
    ichthyo.species_id = "SMALLINT",
    ichthyo.tally      = "INTEGER"),
  verbose        = TRUE)
} # }