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Create a table in the database based on an Arrow object

Source: R/22-dbCreateTableArrow.R
dbCreateTableArrow.Rd

[Experimental]

The default dbCreateTableArrow() method determines the R data types of the Arrow schema associated with the Arrow object, and calls dbCreateTable(). Backends that implement dbAppendTableArrow() should typically also implement this generic. Use dbCreateTable() to create a table from the column types as defined in a data frame.

Methods in other packages

This documentation page describes the generics. Refer to the documentation pages linked below for the documentation for the methods that are implemented in various backend packages.

Usage

dbCreateTableArrow(conn, name, value, ..., temporary = FALSE)

Arguments

conn

A DBIConnection object, as returned by dbConnect().

name

The table name, passed on to dbQuoteIdentifier(). Options are:

  • a character string with the unquoted DBMS table name, e.g. "table_name",

  • a call to Id() with components to the fully qualified table name, e.g. Id(schema = "my_schema", table = "table_name")

  • a call to SQL() with the quoted and fully qualified table name given verbatim, e.g. SQL('"my_schema"."table_name"')

value

An object for which a schema can be determined via nanoarrow::infer_nanoarrow_schema().

...

Other parameters passed on to methods.

temporary

If TRUE, will generate a temporary table.

Value

dbCreateTableArrow() returns TRUE, invisibly.

Failure modes

If the table exists, an error is raised; the remote table remains unchanged.

An error is raised when calling this method for a closed or invalid connection. An error is also raised if name cannot be processed with dbQuoteIdentifier() or if this results in a non-scalar. Invalid values for the temporary argument (non-scalars, unsupported data types, NA, incompatible values, duplicate names) also raise an error.

Additional arguments

The following arguments are not part of the dbCreateTableArrow() generic (to improve compatibility across backends) but are part of the DBI specification:

  • temporary (default: FALSE)

They must be provided as named arguments. See the "Specification" and "Value" sections for details on their usage.

Specification

The name argument is processed as follows, to support databases that allow non-syntactic names for their objects:

  • If an unquoted table name as string: dbCreateTableArrow() will do the quoting, perhaps by calling dbQuoteIdentifier(conn, x = name)

  • If the result of a call to dbQuoteIdentifier(): no more quoting is done

The value argument can be:

  • a data frame,

  • a nanoarrow array

  • a nanoarrow array stream (which will still contain the data after the call)

  • a nanoarrow schema

If the temporary argument is TRUE, the table is not available in a second connection and is gone after reconnecting. Not all backends support this argument. A regular, non-temporary table is visible in a second connection, in a pre-existing connection, and after reconnecting to the database.

SQL keywords can be used freely in table names, column names, and data. Quotes, commas, and spaces can also be used for table names and column names, if the database supports non-syntactic identifiers.

See also

Other DBIConnection generics: DBIConnection-class, dbAppendTable(), dbAppendTableArrow(), dbCreateTable(), dbDataType(), dbDisconnect(), dbExecute(), dbExistsTable(), dbGetException(), dbGetInfo(), dbGetQuery(), dbGetQueryArrow(), dbIsReadOnly(), dbIsValid(), dbListFields(), dbListObjects(), dbListResults(), dbListTables(), dbQuoteIdentifier(), dbReadTable(), dbReadTableArrow(), dbRemoveTable(), dbSendQuery(), dbSendQueryArrow(), dbSendStatement(), dbUnquoteIdentifier(), dbWriteTable(), dbWriteTableArrow()

Examples

con <- dbConnect(RSQLite::SQLite(), ":memory:")
ptype <- data.frame(a = numeric())
dbCreateTableArrow(con, "df", nanoarrow::infer_nanoarrow_schema(ptype))
dbReadTable(con, "df")
#> [1] a
#> <0 rows> (or 0-length row.names)
dbDisconnect(con)