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I'm new to QGIS and recently I've been trying to dissolve two large shapefiles together after they have been merged. It's taking an awful lot of time for each operation and I'm trying to speed up the process.

I've noticed that, once the dissolve operation completes, the destination file has a mix of different data types, such as .shx, .dbf, .qpj, and of course .shp. I am wondering if I can make QGIS to generate .shp files only in a dissolve operation and, if I can, would doing so make the dissolve operation complete faster?

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I don't think you can have a functioning shapefile with just the ".shp" file. You need the ".shp", ".shx" and ".dbf" files together for the shapefile to work.

Check out these links.

Shapefile Extensions - ESRI Website

Shapefile Wikipedia

In summary at a minimum you need a:

  1. shp - The file that stores the geometry.
  2. shx - The index file that stores the index of the feature geometry.
  3. dbf - The dBase file that stores the attribution.

As for speeding up the dissolve the try the processing toolbox, the SAGA polygon dissolve or GRASS method mentioned in this link and in previous answers.

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It is mandatory to have these additional files, to handle a .shp file correctly, so you can't suppress the creation of them. See the Wikipedia article for more information regarding this topic.

Regarding the slow performance of the standard QGIS dissolve operation, you can also try to use v.dissolve from GRASS which you can access via Processing -> Toolbox. This should have in general a better performance.

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A ShapeFile is made up of at least two files: .shp - This stores the geometry .shx - This stores the geometry index

A ShapeFile should also contain a: .dbf - This stores your attributes

And ideally also a: .prj - This stores information about your projection

A ShapeFile may also contain other files.

The removal of any of these will not speed up processing. Likely it will slow it down.

What might help:

  • Generate QGIS indexes: Go into the layer properties> General> From coordinate reference system> Create spatial index Use a database.
  • Do your dissolving in PostGIS.

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