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Insert rows into a table from an Arrow stream

Source: R/21-dbAppendTableArrow.R
dbAppendTableArrow.Rd

[Experimental]

The dbAppendTableArrow() method assumes that the table has been created beforehand, e.g. with dbCreateTableArrow(). The default implementation calls dbAppendTable() for each chunk of the stream. Use dbAppendTable() to append data from 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

dbAppendTableArrow(conn, name, value, ...)

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 coercible with nanoarrow::as_nanoarrow_array_stream().

...

Other parameters passed on to methods.

Value

dbAppendTableArrow() returns a scalar numeric.

Failure modes

If the table does not exist, or the new data in values is not a data frame or has different column names, 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 DBI::dbQuoteIdentifier() or if this results in a non-scalar.

Specification

SQL keywords can be used freely in table names, column names, and data. Quotes, commas, spaces, and other special characters such as newlines and tabs, can also be used in the data, and, if the database supports non-syntactic identifiers, also for table names and column names.

The following data types must be supported at least, and be read identically with DBI::dbReadTable():

  • integer

  • numeric (the behavior for Inf and NaN is not specified)

  • logical

  • NA as NULL

  • 64-bit values (using "bigint" as field type); the result can be

    • converted to a numeric, which may lose precision,

    • converted a character vector, which gives the full decimal representation

    • written to another table and read again unchanged

  • character (in both UTF-8 and native encodings), supporting empty strings (before and after non-empty strings)

  • factor (possibly returned as character)

  • objects of type blob::blob (if supported by the database)

  • date (if supported by the database; returned as Date) also for dates prior to 1970 or 1900 or after 2038

  • time (if supported by the database; returned as objects that inherit from difftime)

  • timestamp (if supported by the database; returned as POSIXct respecting the time zone but not necessarily preserving the input time zone), also for timestamps prior to 1970 or 1900 or after 2038 respecting the time zone but not necessarily preserving the input time zone)

Mixing column types in the same table is supported.

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: dbAppendTableArrow() will do the quoting, perhaps by calling dbQuoteIdentifier(conn, x = name)

  • If the result of a call to DBI::dbQuoteIdentifier(): no more quoting is done to support databases that allow non-syntactic names for their objects:

The value argument must be a data frame with a subset of the columns of the existing table. The order of the columns does not matter.

See also

Other DBIConnection generics: DBIConnection-class, dbAppendTable(), dbCreateTable(), dbCreateTableArrow(), 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:")
dbCreateTableArrow(con, "iris", iris[0, ])
dbAppendTableArrow(con, "iris", iris[1:5, ])
#> [1] 5
dbReadTable(con, "iris")
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> 1          5.1         3.5          1.4         0.2  setosa
#> 2          4.9         3.0          1.4         0.2  setosa
#> 3          4.7         3.2          1.3         0.2  setosa
#> 4          4.6         3.1          1.5         0.2  setosa
#> 5          5.0         3.6          1.4         0.2  setosa
dbDisconnect(con)