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Filter a database table based on a version string.

filter_on_version_string.Rd

Filtering a database table based on the version you wish to download is a common task. In the CL-PFU database, we store data in a compressed format where identical data points are not duplicated. Rather, they are stored in a single row with the ValidFromVersion and ValidToVersion columns incremented appropriately.

Usage

filter_on_version_string(
  tbl,
  version_string,
  db_table_name,
  collect = FALSE,
  conn = NULL,
  schema = schema_from_conn(conn = conn),
  fk_parent_tables = get_all_fk_tables(conn = conn, schema = schema),
  valid_from_version_colname = PFUPipelineTools::dataset_info$valid_from_version_colname,
  valid_to_version_colname = PFUPipelineTools::dataset_info$valid_to_version_colname
)

Arguments

tbl

The tbl object that should be filtered.

version_string

A vector of version strings to indicate the desired version(s).

db_table_name

The name of the table to be filtered.

collect

A boolean that tells whether to collect tbl from conn before returning. Default is FALSE.

conn

An optional database connection. Necessary only for the default values of schema and fk_parent_tables. Default is NULL.

schema

The database schema (a dm object). Default calls schema_from_conn(), but you can supply a pre-computed schema for speed. Needed only when decode_fks = TRUE (the default). If foreign keys are not being decoded, setting NULL may improve speed.

fk_parent_tables

Foreign key parent tables to assist decoding foreign keys. Default calls get_all_fk_tables().

valid_from_version_colname

The name of the ValidFromVersion column. Default is PFUPipelineTools::dataset_info$valid_from_version_colname.

valid_to_version_colname

The name of the ValidToVersion column. Default is PFUPipelineTools::dataset_info$valid_to_version_colname.

Value

A filtered version of tbl.

Details

The desired version is supplied in the version_string argument, which can be a vector of any length.

If both tbl and db_table_name are provided, db_table_name is ignored.