Get the current schema/catalog of a database-related objects

Usage

get_catalog(obj, ...)

# S3 method for class '`Microsoft SQL Server`'
get_catalog(obj, temporary = FALSE, ...)

get_schema(obj, ...)

# S3 method for class 'PqConnection'
get_schema(obj, temporary = FALSE, ...)

# S3 method for class 'SQLiteConnection'
get_schema(obj, temporary = FALSE, ...)

Arguments

obj: (DBIConnection(1), tbl_dbi(1), Id(1))
The object from which to retrieve a schema/catalog.
...: Further arguments passed to methods.
temporary: (logical(1))
Should the reference be to the temporary schema/catalog?

Value

The catalog is extracted from obj depending on the type of input:

For get_catalog.Microsoft SQL Server, the current database context of the connection or "tempdb" if temporary = TRUE.
For get_schema.tbl_dbi the catalog is determined via id().
For get_catalog.\\*, NULL is returned.

The schema is extracted from obj depending on the type of input:

For get_schema.DBIConnection(), the current schema of the connection if temporary = FALSE. See "Default schema" for more. If temporary = TRUE, the temporary schema of the connection is returned.
For get_schema.tbl_dbi() the schema is determined via id().
For get_schema.Id(), the schema is extracted from the Id specification.

Default schema

In some backends, it is possible to modify settings so that when a schema is not explicitly stated in a query, the backend searches for the table in this schema by default. For Postgres databases, this can be shown with SELECT CURRENT_SCHEMA() (defaults to public) and modified with SET search_path TO { schema }.

For SQLite databases, a temp schema for temporary tables always exists as well as a main schema for permanent tables. Additional databases may be attached to the connection with a named schema, but as the attachment must be made after the connection is established, get_schema will never return any of these, as the default schema will always be main.

Examples

  conn <- get_connection()

  dplyr::copy_to(conn, mtcars, name = "mtcars", temporary = FALSE)

  get_schema(conn)
#> [1] "main"
  get_schema(get_table(conn, id("mtcars", conn = conn)))
#> [1] "main"

  get_catalog(conn)
#> NULL
  get_catalog(get_table(conn, id("mtcars", conn = conn)))
#> NULL

  close_connection(conn)