28.2.8. Vector miscellaneous

28.2.8.1. Build virtual vector

Creates a virtual vector layer that contains a set of vector layers. The output virtual vector layer will not be opened in the current project.

This algorithm is especially useful in case another algorithm needs multiple layers but accept only one vrt in which the layers are specified.

Parameters

Label	Name	Type	Description
Input datasources	INPUT	[vector: any] [list]	Select the vector layers you want to use to build the virtual vector
Create “unioned” VRT	UNIONED	[boolean] Default: False	Check if you want to unite all the vectors in a single vrt file
Virtual vector	OUTPUT	[same as input] Default: [Save to temporary file]	Specify the output layer containing only the duplicates. One of: Save to a Temporary File Save to File…

Outputs

Label	Name	Type	Description
Virtual vector	OUTPUT	[vector: any]	The output virtual vector made from the chosen sources

Python code

Algorithm ID: gdal:buildvirtualvector

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.8.2. Execute SQL

Runs a simple or complex query with SQL syntax on the source layer. The result of the query will be added as a new layer.

This algorithm is derived from the GDAL ogr2ogr utility.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: any]	OGR-supported input vector layer
SQL expression	SQL	[string]	Defines the SQL query, for example SELECT * FROM my_table WHERE name is not null.
SQL dialect	DIALECT	[enumeration] Default: 0	SQL dialect to use. One of: 0 — None 1 — OGR SQL 2 — SQLite
SQL result	OUTPUT	[vector: any]	Specification of the output layer. One of: Save to a Temporary File Save to File… For Save to File, the output format has to be specified. All GDAL vector formats are supported. For Save to a Temporary File the default output vector layer format will be used.

Advanced parameters

Label	Name	Type	Description
Additional creation options Optional	OPTIONS	[string] Default: ‘’ (no additional options)	Additional GDAL creation options.

Outputs

Label	Name	Type	Description
SQL result	OUTPUT	[vector: any]	Vector layer created by the query

Python code

Algorithm ID: gdal:executesql

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.8.3. Export to PostgreSQL (available connections)

Imports vector layers inside a PostgreSQL database on the basis of an available connection. The connection has to be defined properly beforehand. Be aware that the checkboxes ‘Save Username’ and ‘Save Password’ are activated. Then you can use the algorithm.

This algorithm is derived from the GDAL ogr2ogr utility.

Parameters

Label	Name	Type	Description
Database (connection name)	DATABASE	[string]	The PostgreSQL database to connect to
Input layer	INPUT	[vector: any]	OGR-supported vector layer to export to the database
Shape encoding Optional	SHAPE_ENCODING	[string] Default: ‘’	Sets the encoding to apply to the data
Output geometry type	GTYPE	[enumeration] Default: 0	Defines the output geometry type. One of: 0 — 1 — NONE 2 — GEOMETRY 3 — POINT 4 — LINESTRING 5 — POLYGON 6 — GEOMETRYCOLLECTION 7 — MULTIPOINT 8 — MULTIPOLYGON 9 — MULTILINESTRING
Assign an output CRS Optional	A_SRS	[crs] Default: None	Defines the output CRS of the database table
Reproject to this CRS on output Optional	T_SRS	[crs] Default: None	Reprojects/transforms to this CRS on output
Override source CRS Optional	S_SRS	[crs] Default: None	Overrides the input layer CRS
Schema (schema name) Optional	SCHEMA	[string] Default: ‘public’	Defines the schema for the database table
Table to export to (leave blank to use layer name) Optional	TABLE	[string] Default: ‘’	Defines a name for the table that will be imported into the database. By default the table name is the name of the input vector file.
Primary Key (new field) Optional	PK	[string] Default: ‘id’	Defines which attribute field will be the primary key of the database table
Primary Key (existing field, used if the above option is left empty) Optional	PRIMARY_KEY	[tablefield: any] Default: None	Defines which attribute field in the exported layer will be the primary key of the database table
Geometry column name Optional	GEOCOLUMN	[string] Default: ‘geom’	Defines in which attribute field of the database there will be the geometry information
Vector dimensions Optional	DIM	[enumeration] Default: 0 (2D)	Defines if the vector file to be imported has 2D or 3D data. One of: 0 — 2 1 — 3
Distance tolerance for simplification Optional	SIMPLIFY	[string] Default: ‘’	Defines a distance tolerance for the simplification of the vector geometries to be imported. By default there is no simplification.
Maximum distance between 2 nodes (densification) Optional	SEGMENTIZE	[string] Default: ‘’	The maximum distance between two nodes. Used to create intermediate points. By default there is no densification.
Select features by extent (defined in input layer CRS) Optional	SPAT	[extent] Default: None	You can select features from a given extent that will be in the output table. Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
Clip the input layer using the above (rectangle) extent Optional	CLIP	[boolean] Default: False	The input layer will be clipped by the extent you defined before
Select features using a SQL “WHERE” statement (Ex: column=”value”) Optional	WHERE	[string] Default: ‘’	Defines with a SQL “WHERE” statement which features should be selected from the input layer
Group N features per transaction (Default: 2000) Optional	GT	[string] Default: ‘’	You can group the input features in transactions where N defines the size. By default N limits the transaction size to 20000 features.
Overwrite existing table Optional	OVERWRITE	[boolean] Default: True	If there is a table with the same name in the database, and if this option is set to True, the table will be overwritten.
Append to existing table Optional	APPEND	[boolean] Default: False	If checked / True the vector data will be appended to an existing table. New fields found in the input layer are ignored. By default a new table will be created.
Append and add new fields to existing table Optional	ADDFIELDS	[boolean] Default: False	If activated the vector data will be appended to an existing table, there won’t be a new table created. New fields found in input layer are added to the table. By default a new table will be created.
Do not launder columns/table names Optional	LAUNDER	[boolean] Default: False	With this option checked you can prevent the default behaviour (converting column names to lowercase, removing spaces and other invalid characters).
Do not create Spatial Index Optional	INDEX	[boolean] Default: False	Prevents a spatial index for the output table from being created. By default, a spatial index is added.
Continue after a failure, skipping the failed feature Optional	SKIPFAILURES	[boolean] Default: False
Promote to Multipart Optional	PROMOTETOMULTI	[boolean] Default: True	Casts features geometry type to multipart in the output table
Keep width and precision of input attributes Optional	PRECISION	[boolean] Default: True	Avoids modifying column attributes to comply with input data
Additional creation options Optional	OPTIONS	[string] Default: ‘’ (no additional options)	Additional GDAL creation options.

Outputs

This algorithm has no output.

Python code

Algorithm ID: gdal:importvectorintopostgisdatabaseavailableconnections

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.8.4. Export to PostgreSQL (new connection)

Imports vector layers inside a PostgreSQL database. A new connection to the PostGIS database must be created.

This algorithm is derived from the GDAL ogr2ogr utility.

Parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: any]	OGR-supported vector layer to export to the database
Shape encoding Optional	SHAPE_ENCODING	[string] Default: ‘’	Sets the encoding to apply to the data
Output geometry type	GTYPE	[enumeration] Default: 0	Defines the output geometry type. One of: 0 — 1 — NONE 2 — GEOMETRY 3 — POINT 4 — LINESTRING 5 — POLYGON 6 — GEOMETRYCOLLECTION 7 — MULTIPOINT 8 — MULTIPOLYGON 9 — MULTILINESTRING
Assign an output CRS Optional	A_SRS	[crs] Default: None	Defines the output CRS of the database table
Reproject to this CRS on output Optional	T_SRS	[crs] Default: None	Reprojects/transforms to this CRS on output
Override source CRS Optional	S_SRS	[crs] Default: None	Overrides the input layer CRS
Host Optional	HOST	[string] Default: ‘localhost’	Name of the database host
Port Optional	PORT	[string] Default: ‘5432’	Port number the PostgreSQL database server listens on
Username Optional	USER	[string] Default: ‘’	User name used to log in to the database
Database name Optional	DBNAME	[string] Default: ‘’	Name of the database
Password Optional	PASSWORD	[string] Default: ‘’	Password used with Username to connect to the database
Schema (schema name) Optional	SCHEMA	[string] Default: ‘public’	Defines the schema for the database table
Table name, leave blank to use input name Optional	TABLE	[string] Default: ‘’	Defines a name for the table that will be imported into the database. By default the table name is the name of the input vector file.
Primary Key (new field) Optional	PK	[string] Default: ‘id’	Defines which attribute field will be the primary key of the database table
Primary Key (existing field, used if the above option is left empty) Optional	PRIMARY_KEY	[tablefield: any] Default: None	Defines which attribute field in the exported layer will be the primary key of the database table
Geometry column name Optional	GEOCOLUMN	[string] Default: ‘geom’	Defines in which attribute field to store the geometry information
Vector dimensions Optional	DIM	[enumeration] Default: 0 (2D)	Defines if the vector file to be imported has 2D or 3D data. One of: 0 — 2D 1 — 3D
Distance tolerance for simplification Optional	SIMPLIFY	[string] Default: ‘’	Defines a distance tolerance for the simplification of the vector geometries to be imported. By default there is no simplification.
Maximum distance between 2 nodes (densification) Optional	SEGMENTIZE	[string] Default: ‘’	The maximum distance between two nodes. Used to create intermediate points. By default there is no densification.
Select features by extent (defined in input layer CRS) Optional	SPAT	[extent] Default: None	You can select features from a given extent that will be in the output table. Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
Clip the input layer using the above (rectangle) extent Optional	CLIP	[boolean] Default: False	The input layer will be clipped by the extent you defined before
Fields to include (leave empty to use all fields) Optional	FIELDS	[string] [list] Default: []	Defines fields to keep from the imported vector file. If none is selected, all the fields are imported.
Select features using a SQL “WHERE” statement (Ex: column=”value”) Optional	WHERE	[string] Default: ‘’	Defines with a SQL “WHERE” statement which features should be selected for the output table
Group N features per transaction (Default: 2000) Optional	GT	[string] Default: ‘’	You can group the input features in transactions where N defines the size. By default N limits the transaction size to 20000 features.
Overwrite existing table Optional	OVERWRITE	[boolean] Default: True	If there is a table with the same name in the database, and if this option is set to True, the table will be overwritten.
Append to existing table Optional	APPEND	[boolean] Default: False	If checked / True the vector data will be appended to an existing table. New fields found in the input layer are ignored. By default a new table will be created.
Append and add new fields to existing table Optional	ADDFIELDS	[boolean] Default: False	If activated the vector data will be appended to an existing table, there won’t be created a new table. New fields found in input layer are added to the table. By default a new table will be created.
Do not launder columns/table names Optional	LAUNDER	[boolean] Default: False	With this option checked you can prevent the default behaviour (converting column names to lowercase, removing spaces and other invalid characters).
Do not create Spatial Index Optional	INDEX	[boolean] Default: False	Prevents a spatial index for the output table from being created. By default, a spatial index is added.
Continue after a failure, skipping the failed feature Optional	SKIPFAILURES	[boolean] Default: False
Promote to Multipart Optional	PROMOTETOMULTI	[boolean] Default: True	Casts features geometry type to multipart in the output table
Keep width and precision of input attributes Optional	PRECISION	[boolean] Default: True	Avoids modifying column attributes to comply with input data
Additional creation options Optional	OPTIONS	[string] Default: ‘’ (no additional options)	Additional GDAL creation options.

Outputs

This algorithm has no output.

Python code

Algorithm ID: gdal:importvectorintopostgisdatabasenewconnection

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.8.5. Vector Information

Creates an information file that lists information about an OGR-supported data source. The output will be shown in a ‘Result’ window and can be written into a HTML-file. The information includes the geometry type, feature count, the spatial extent, the projection information, the list of attributes and related type, list of relations and field domains, and many more.

This algorithm is derived from the GDAL ogrinfo utility.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: any]	Input vector layer
Enable listing of all layers in the dataset	ALL_LAYERS	[boolean] Default: False	If checked, QGIS will output the information of all the layers in the input dataset instead of information of the first layer only. Convenient when a multi layer format (GeoPackage, GML, KML, SpatiaLite, SQLite, …) is used as input.
Summary output only	SUMMARY_ONLY	[boolean] Default: True	Suppress listing of individual features and show only summary information like projection, schema, feature count and extents.
Suppress metadata info	NO_METADATA	[boolean] Default: False	Suppress metadata printing. Some datasets may contain a lot of metadata strings.
Layer information	OUTPUT	[html] Default: [Save to temporary file]	Specify the output HTML file that includes the file information. One of: Save to a Temporary File Save to File… If no HTML-file is defined the output will be written to a temporary file

Advanced parameters

Label	Name	Type	Description
Additional command line parameters Optional	EXTRA	[string] Default: ‘’ (no additional options)	Add extra GDAL command line options

Outputs

Label	Name	Type	Description
Layer information	OUTPUT	[html]	The output HTML-file that includes the file information.

Python code

Algorithm ID: gdal:ogrinfo

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.8.6. Vector Information (JSON)

Creates an information file that lists information about an OGR-supported data source. The output will be shown in a ‘Result’ window and can be written into a .JSON file. The information includes the geometry type, feature count, the spatial extent, the projection information, the list of attributes and related type, list of relations and field domains, and many more.

This algorithm is derived from the GDAL ogrinfo utility.

Requires version of GDAL >= 3.7

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: any]	Input vector layer
Enable listing of all layers in the dataset	ALL_LAYERS	[boolean] Default: False	If checked, QGIS will output the information of all the layers in the input dataset instead of information of the first layer only. Convenient when a multi layer format (GeoPackage, GML, KML, SpatiaLite, SQLite, …) is used as input.
Enable listing of features	FEATURES	[boolean] Default: False
Suppress metadata info	NO_METADATA	[boolean] Default: False	Suppress metadata printing. Some datasets may contain a lot of metadata strings.
Layer information	OUTPUT	[file] Default: [Save to temporary file]	Specify the output JSON file that includes the file information. One of: Save to a Temporary File Save to File… If no JSON file is defined the output will be written to a temporary file

Advanced parameters

Label	Name	Type	Description
Additional command line parameters Optional	EXTRA	[string] Default: ‘’ (no additional options)	Add extra GDAL command line options

Outputs

Label	Name	Type	Description
Layer information	OUTPUT	[file]	The output .JSON file that includes the file information.

Python code

Algorithm ID: gdal:ogrinfojson

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.