ESRI Shapefile / DBF

Driver short name

ESRI Shapefile

Driver built-in by default

This driver is built-in by default

All varieties of ESRI Shapefiles should be available for reading, creation and editing. The driver can also handle standalone DBF files without associated .shp files.

Normally the OGR Shapefile driver treats a whole directory of shapefiles as a dataset, and a single shapefile within that directory as a layer. In this case the directory name should be used as the dataset name. However, it is also possible to use one of the files (.shp, .shx or .dbf) in a shapefile set as the dataset name, and then it will be treated as a dataset with one layer.

Note that when reading a Shapefile of type SHPT_ARC, the corresponding layer will be reported as of type wkbLineString, but depending on the number of parts of each geometry, the actual type of the geometry for each feature can be either OGRLineString or OGRMultiLineString. The same applies for SHPT_POLYGON shapefiles, reported as layers of type wkbPolygon, but depending on the number of parts of each geometry, the actual type can be either OGRPolygon or OGRMultiPolygon.

Measures (M coordinate) are supported. A Shapefile with measures is created if the specified geometry type is measured or an appropriate layer creation option is used. When a shapefile which may have measured geometries is opened, the first shape is examined and if it uses measures, the geometry type of the layer is set accordingly. This behavior can be changed with the ADJUST_GEOM_TYPE open option.

MultiPatch files are read and each patch geometry is turned into a TIN or a GEOMETRYCOLLECTION of TIN representation for fans and meshes.

If a .prj files in old Arc/Info style or new ESRI OGC WKT style is present, it will be read and used to associate a projection with features. Starting with GDAL 2.3, a match will be attempted with the EPSG databases to identify the SRS of the .prj with an entry in the catalog.

The read driver assumes that multipart polygons follow the specification, that is to say the vertices of outer rings should be oriented clockwise on the X/Y plane, and those of inner rings counterclockwise. If a Shapefile is broken w.r.t. that rule, it is possible to define the configuration option OGR_ORGANIZE_POLYGONS to DEFAULT to proceed to a full analysis based on topological relationships of the parts of the polygons so that the resulting polygons are correctly defined in the OGC Simple Feature convention.

Driver capabilities

Supports Create()

This driver supports the GDALDriver::Create() operation

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)

Encoding

An attempt is made to read the code page setting in the .cpg file, or as a fallback in the LDID/codepage setting from the .dbf file, and use it to translate string fields to UTF-8 on read, and back when writing. LDID "87 / 0x57" is treated as ISO-8859-1 which may not be appropriate. The SHAPE_ENCODING configuration option may be used to override the encoding interpretation of the shapefile with any encoding supported by CPLRecode or to "" to avoid any recoding.

Starting with GDAL 3.1, the following metadata items are available in the "SHAPEFILE" domain:

  • LDID_VALUE=integer: Raw LDID value from the DBF header. Only present if this value is not zero.

  • ENCODING_FROM_LDID=string: Encoding name deduced from LDID_VALUE. Only present if LDID_VALUE is present

  • CPG_VALUE=string: Content of the .cpg file. Only present if the file exists.

  • ENCODING_FROM_CPG=string: Encoding name deduced from CPG_VALUE. Only present if CPG_VALUE is present

  • SOURCE_ENCODING=string: Encoding used by GDAL to encode/recode strings. If the user has provided the SHAPE_ENCODING configuration option or ENCODING open option have been provided (included to empty value), then their value is used to fill this metadata item. Otherwise it is equal to ENCODING_FROM_CPG if it is present. Otherwise it is equal to ENCODING_FROM_LDID.

Spatial and attribute indexing

The OGR Shapefile driver supports spatial indexing and a limited form of attribute indexing.

The spatial indexing uses the same .qix quadtree spatial index files that are used by UMN MapServer. Spatial indexing can accelerate spatially filtered passes through large datasets to pick out a small area quite dramatically.

It can also use the ESRI spatial index files (.sbn / .sbx), but writing them is not supported currently.

To create a spatial index (in .qix format), issue a SQL command of the form

CREATE SPATIAL INDEX ON tablename [DEPTH N]

where optional DEPTH specifier can be used to control number of index tree levels generated. If DEPTH is omitted, tree depth is estimated on basis of number of features in a shapefile and its value ranges from 1 to 12.

To delete a spatial index issue a command of the form

DROP SPATIAL INDEX ON tablename

Otherwise, the MapServer shptree utility can be used:

shptree <shpfile> [<depth>] [<index_format>]

More information is available about this utility at the MapServer shptree page

Currently the OGR Shapefile driver only supports attribute indexes for looking up specific values in a unique key column. To create an attribute index for a column issue an SQL command of the form "CREATE INDEX ON tablename USING fieldname". To drop the attribute indexes issue a command of the form "DROP INDEX ON tablename". The attribute index will accelerate WHERE clause searches of the form "fieldname = value". The attribute index is actually stored as a mapinfo format index and is not compatible with any other shapefile applications.

Creation Issues

The Shapefile driver treats a directory as a dataset, and each Shapefile set (.shp, .shx, and .dbf) as a layer. The dataset name will be treated as a directory name. If the directory already exists it is used and existing files in the directory are ignored. If the directory does not exist it will be created.

As a special case attempts to create a new dataset with the extension .shp will result in a single file set being created instead of a directory.

ESRI shapefiles can only store one kind of geometry per layer (shapefile). On creation this is may be set based on the source file (if a uniform geometry type is known from the source driver), or it may be set directly by the user with the layer creation option SHPT (shown below). If not set the layer creation will fail. If geometries of incompatible types are written to the layer, the output will be terminated with an error.

Note that this can make it very difficult to translate a mixed geometry layer from another format into Shapefile format using ogr2ogr, since ogr2ogr has no support for separating out geometries from a source layer.

Shapefile feature attributes are stored in an associated .dbf file, and so attributes suffer a number of limitations:

  • Attribute names can only be up to 10 characters long. The OGR Shapefile driver tries to generate unique field names. Successive duplicate field names, including those created by truncation to 10 characters, will be truncated to 8 characters and appended with a serial number from 1 to 99.

    For example:

    • a → a, a → a_1, A → A_2;

    • abcdefghijk → abcdefghij, abcdefghijkl → abcdefgh_1

  • Only Integer, Integer64, Real, String and Date (not DateTime, just year/month/day) field types are supported. The various list, and binary field types cannot be created.

  • The field width and precision are directly used to establish storage size in the .dbf file. This means that strings longer than the field width, or numbers that don't fit into the indicated field format will suffer truncation.

  • Integer fields without an explicit width are treated as width 9, and extended to 10 or 11 if needed.

  • Integer64 fields without an explicit width are treated as width 18, and extended to 19 or 20 if needed.

  • Real (floating point) fields without an explicit width are treated as width 24 with 15 decimal places of precision.

  • String fields without an assigned width are treated as 80 characters.

Also, .dbf files are required to have at least one field. If none are created by the application an "FID" field will be automatically created and populated with the record number.

The OGR shapefile driver supports rewriting existing shapes in a shapefile as well as deleting shapes. Deleted shapes are marked for deletion in the .dbf file, and then ignored by OGR. To actually remove them permanently (resulting in renumbering of FIDs) invoke the SQL 'REPACK <tablename>' via the datasource ExecuteSQL() method.

REPACK will also result in .shp being rewritten if a feature geometry has been modified with SetFeature() and resulted in a change of the size the binary encoding of the geometry in the .shp file.

Starting with GDAL 2.2, REPACK is also done automatically at file closing, or at FlushCache()/SyncToDisk() time, since shapefiles with holes can cause interoperability issues with other software.

Field sizes

The driver knows to auto-extend string and integer fields (up to the 255 bytes limit imposed by the DBF format) to dynamically accommodate for the length of the data to be inserted.

It is also possible to force a resize of the fields to the optimal width by issuing a SQL 'RESIZE <tablename>' via the datasource ExecuteSQL() method. This is convenient in situations where the default column width (80 characters for a string field) is bigger than necessary.

Spatial extent

Shapefiles store the layer spatial extent in the .SHP file. The layer spatial extent is automatically updated when inserting a new feature in a shapefile. However when updating an existing feature, if its previous shape was touching the bounding box of the layer extent but the updated shape does not touch the new extent, the computed extent will not be correct. It is then necessary to force a recomputation by invoking the SQL 'RECOMPUTE EXTENT ON <tablename>' via the datasource ExecuteSQL() method. The same applies for the deletion of a shape.

Size Issues

Geometry: The Shapefile format explicitly uses 32bit offsets and so cannot go over 8GB (it actually uses 32bit offsets to 16bit words), but the OGR shapefile implementation has a limitation to 4GB.

Attributes: The dbf format does not have any offsets in it, so it can be arbitrarily large.

However, for compatibility with other software implementation, it is not recommended to use a file size over 2GB for both .SHP and .DBF files.

The 2GB_LIMIT=YES layer creation option can be used to strictly enforce that limit. For update mode, the SHAPE_2GB_LIMIT configuration option can be set to YES for similar effect. If nothing is set, a warning will be emitted when the 2GB limit is reached.

Compressed files

Starting with GDAL 3.1, the driver can also support reading, creating and editing .shz files (ZIP files containing the .shp, .shx, .dbf and other side-car files of a single layer) and .shp.zip files (ZIP files contains one or several layers). Creation and editing involves the creation of temporary files.

Open options

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). The following open options are supported:

  • ENCODING=[<encoding_name>​/​""]: Override the encoding interpretation of the shapefile with any encoding supported by CPLRecode or to "" to avoid any recoding.

  • DBF_DATE_LAST_UPDATE=YYYY-MM-DD: Modification date to write in DBF header with year-month-day format. If not specified, current date is used.

  • ADJUST_TYPE=[YES​/​NO]: Defaults to NO. Set to YES to read the whole .dbf to adjust Real->Integer/Integer64 or Integer64->Integer field types when possible. This can be used when field widths are ambiguous and that by default OGR would select the larger data type. For example, a numeric column with 0 decimal figures and with width of 10/11 character may hold Integer or Integer64, and with width 19/20 may hold Integer64 or larger integer (hold as Real)

  • ADJUST_GEOM_TYPE=[NO​/​FIRST_SHAPE​/​ALL_SHAPES]: Defaults to FIRST_SHAPE. Defines how layer geometry type is computed, in particular to distinguish shapefiles that have shapes with significant values in the M dimension from the ones where the M values are set to the nodata value. By default (FIRST_SHAPE), the driver will look at the first shape and if it has M values it will expose the layer as having a M dimension. By specifying ALL_SHAPES, the driver will iterate over features until a shape with a valid M value is found to decide the appropriate layer type.

  • AUTO_REPACK=[YES​/​NO]: Defaults to YES. Whether the shapefile should be automatically repacked when needed, at dataset closing or at FlushCache()/SyncToDisk() time.

  • DBF_EOF_CHAR=[YES​/​NO]: Defaults to YES. Whether the .DBF should be terminated by a 0x1A end-of-file character, as in the DBF spec and done by other software vendors. Previous GDAL versions did not write one.

Dataset creation options

None

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:

  • SHPT=<type>: Override the type of shapefile created. Can be one of NULL for a simple .dbf file with no .shp file, POINT, ARC, POLYGON or MULTIPOINT for 2D; POINTZ, ARCZ, POLYGONZ, MULTIPOINTZ or MULTIPATCH for 3D; POINTM, ARCM, POLYGONM or MULTIPOINTM for measured geometries; and POINTZM, ARCZM, POLYGONZM or MULTIPOINTZM for 3D measured geometries. The measure support was added in GDAL 2.1. MULTIPATCH files are supported since GDAL 2.2.

  • ENCODING=value: Set the encoding value in the DBF file. The default value is "LDID/87". It is not clear what other values may be appropriate.

  • RESIZE=[YES​/​NO]: Defaults to NO. Set to YES to resize fields to their optimal size. See above "Field sizes" section.

  • 2GB_LIMIT=[YES​/​NO]: Defaults to NO. Set to YES to enforce the 2GB file size for .SHP or .DBF files.

  • SPATIAL_INDEX=[YES​/​NO]: Defaults to NO. Set to YES to create a spatial index (.qix).

  • DBF_DATE_LAST_UPDATE=<YYYY-MM-DD>: Modification date to write in DBF header with year-month-day format. If not specified, current date is used. Note: behavior of past GDAL releases was to write 1995-07-26

  • AUTO_REPACK=[YES​/​NO]: Defaults to YES. Whether the shapefile should be automatically repacked when needed, at dataset closing or at FlushCache()/SyncToDisk() time.

  • DBF_EOF_CHAR=[YES​/​NO]: Defaults to YES. Whether the .DBF should be terminated by a 0x1A end-of-file character, as in the DBF spec and done by other software vendors. Previous GDAL versions did not write one.

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:

  • SHAPE_REWIND_ON_WRITE=[YES​/​NO]: can be set to NO to prevent the shapefile writer to correct the winding order of exterior/interior rings to be conformant with the one mandated by the Shapefile specification. This can be useful in some situations where a MultiPolygon passed to the shapefile writer is not really a compliant Single Feature polygon, but originates from example from a MultiPatch object (from a Shapefile/FileGDB/PGeo datasource).

    Starting with GDAL 3.7, for Polygon/MultiPolygon, the default value is NO, with the effect that the winding order of rings will be determined from the outer/inner rings of the input Polygon/MultiPolygon, and not as a post process topological analysis like done in previous GDAL versions, which could cause troubles for non-planar 3D geometries.

  • SHAPE_RESTORE_SHX=[YES​/​NO]: Defaults to NO. can be set to YES to restore broken or absent .shx file from associated .shp file during opening.

  • SHAPE_2GB_LIMIT=YES: can be set to YES to strictly enforce the 2 GB file size limit when updating a shapefile. If nothing is set, a warning will be emitted when the 2 GB limit is reached.

  • SHAPE_ENCODING=value: may be used to override the encoding interpretation of the shapefile with any encoding supported by CPLRecode() or to "" to avoid any recoding.

Examples

  • A merge of two shapefiles 'file1.shp' and 'file2.shp' into a new file 'file_merged.shp' is performed like this:

    ogr2ogr file_merged.shp file1.shp
ogr2ogr -update -append file_merged.shp file2.shp -nln file_merged

    The second command is opening file_merged.shp in update mode, and trying to find existing layers and append the features being copied.

    The -nln option sets the name of the layer to be copied to.

  • Building a spatial index :

    ogrinfo file1.shp -sql "CREATE SPATIAL INDEX ON file1"

  • Resizing columns of a DBF file to their optimal size :

    ogrinfo file1.dbf -sql "RESIZE file1"

See Also