# Carto

Driver short name

CARTO

Build dependencies

libcurl

This driver can connect to the services implementing the Carto API. GDAL/OGR must be built with Curl support in order for the Carto driver to be compiled.

The driver supports read and write operations.

## Driver capabilities

Supports Create()

This driver supports the `GDALDriver::Create()` operation

Supports Georeferencing

This driver supports georeferencing

## Dataset name syntax

The minimal syntax to open a Carto datasource is :

    Carto:[connection_name]

For single-user accounts, connection name is the account name. For multi-user accounts, connection_name must be the user name, not the account name. Additional optional parameters can be specified after the ':' sign. Currently the following one is supported:

- tables=table_name1[,table_name2]*: A list of table names. This is necessary when you need to access to public tables for example.

If several parameters are specified, they must be separated by a space.

## Authentication

Most operations, in particular write operations, require an authenticated access. The only exception is read-only access to public tables.

Authenticated access is obtained by specifying the API key given in the management interface of the Carto service. It is specified with the CARTO_API_KEY configuration option.

## Geometry

The OGR driver will report as many geometry fields as available in the layer (except the 'the_geom_webmercator' field), following RFC 41.

## Filtering

The driver will forward any spatial filter set with `OGRLayer::SetSpatialFilter()` to the server. It also makes the same for attribute filters set with `OGRLayer::SetAttributeFilter()`.

## Paging

Features are retrieved from the server by chunks of 500 by default. This number can be altered with the `CARTO_PAGE_SIZE` configuration option.

## Write support

Table creation and deletion is possible.

Write support is only enabled when the datasource is opened in update mode.

The mapping between the operations of the Carto service and the OGR concepts is the following :

- `OGRLayer::CreateFeature()` <==> `INSERT` operation

- `OGRLayer::SetFeature()` <==> `UPDATE` operation

- `OGRLayer::DeleteFeature()` <==> `DELETE` operation

- `GDALDataset::CreateLayer()` <==> `CREATE TABLE` operation

- `GDALDataset::DeleteLayer()` <==> `DROP TABLE` operation

When inserting a new feature with `OGRLayer::CreateFeature()`, and if the command is successful, OGR will fetch the returned rowid and use it as the OGR FID.

The above operations are by default issued to the server synchronously with the OGR API call. This however can cause performance penalties when issuing a lot of commands due to many client/server exchanges.

So, on a newly created layer, the `INSERT` of `OGRLayer::CreateFeature()` operations are grouped together in chunks until they reach 15 MB (can be changed with the `CARTO_MAX_CHUNK_SIZE` configuration option, with a value in MB), at which point they are transferred to the server. By setting `CARTO_MAX_CHUNK_SIZE` to 0, immediate transfer occurs.

Warning

Don't use `GDALDataset::DeleteLayer()` and `GDALDataset::CreateLayer()` to overwrite a table. Instead only call `GDALDataset::CreateLayer()` with OVERWRITE=YES. This will avoid CARTO deleting maps that depend on this table

## SQL

SQL commands provided to the `GDALDataset::ExecuteSQL()` call are executed on the server side, unless the OGRSQL dialect is specified. You can use the full power of PostgreSQL + PostGIS SQL capabilities.

## Open options

The following open options are available: Open options can be specified in command-line tools using the syntax `-oo <NAME>=<VALUE>` or by providing the appropriate arguments to `GDALOpenEx()` (C) or `gdal.OpenEx` (Python).

- BATCH_INSERT=[YES​/​NO]: Defaults to `YES`. Whether to group feature insertions in a batch. Only apply in creation or update mode.

- COPY_MODE=[YES​/​NO]: Defaults to `YES`. Using COPY for insertions and reads can result in a performance improvement.

## Layer creation options

Layer creation options can be specified in command-line tools using the syntax `-lco <NAME>=<VALUE>` or by providing the appropriate arguments to `GDALDatasetCreateLayer()` (C) or `Dataset.CreateLayer` (Python). The following layer creation options are supported:

- OVERWRITE=[YES​/​NO]: Defaults to `NO`. Whether to overwrite an existing table with the layer name to be created.

- GEOMETRY_NULLABLE=[YES​/​NO]: Defaults to `YES`. Whether the values of the geometry column can be NULL.

- CARTODBFY=[YES​/​NO]: Defaults to `YES`. Whether the created layer should be "Cartodbifi'ed" (i.e. registered in dashboard). Requires:

  - SRS: Output SRS must be EPSG:4326. You can use `-a_srs` or `-t_srs` to assign or transform to 4326 before importing.

  - Geometry type: Must be different than NONE. You can set to something generic with `-nlt GEOMETRY`.

- LAUNDER=[YES​/​NO]: Defaults to `YES`. This may be "YES" to force new fields created on this layer to have their field names "laundered" into a form more compatible with PostgreSQL. This converts to lower case and converts some special characters like "-" and "#" to "_". If "NO" exact names are preserved. If enabled the table (layer) name will also be laundered.

## Configuration options

Configuration options can be specified in command-line tools using the syntax `--config <NAME>=<VALUE>` or using functions such as `CPLSetConfigOption()` (C) or `gdal.config_options` (Python). The following configuration options are available:

- CARTO_API_URL=value: Defaults to `https://[account_name].carto.com/api/v2/sql`. Can be used to point to another server.

- CARTO_HTTPS=[YES​/​NO]: can be set to NO to use http:// protocol instead of https:// (only if `CARTO_API_URL` is not defined).

- CARTO_MAX_CHUNK_SIZE=value:

- CARTO_API_KEY=value: see following paragraph.

- CARTO_PAGE_SIZE=value: Defaults to `500`. features are retrieved from the server by chunks of 500 by default. This number can be altered with the configuration option.

## Examples

Accessing data from a public table:

    ogrinfo -ro "Carto:gdalautotest2 tables=tm_world_borders_simpl_0_3"

Creating and populating a table from a shapefile:

    ogr2ogr --config CARTO_API_KEY abcdefghijklmnopqrstuvw -f Carto "Carto:myaccount" myshapefile.shp

Creating and populating a table from a CSV containing geometries on EPSG:4326:

    ogr2ogr --config CARTO_API_KEY abcdefghijklmnopqrstuvw -f Carto "Carto:myaccount" file.csv -a_srs 4326 -nlt GEOMETRY

Note

The `-a_srs` and `-nlt` must be provided to CARTODBFY since the information isn't extracted from the CSV.

## See Also

- Carto API overview