How to update SQL query for a virtual layer?

Question

I created a virtual layer which contains all the geometries and attributes from a shapefile using the following code:

vlayer = QgsVectorLayer( "?layer=ogr:path/to/shapefile", "layerName", "virtual" )
QgsMapLayerRegistry.instance().addMapLayer(vlayer)

But now I want to update the SQL query for this virtual layer. Is this possible using PyQGIS?

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Example:

How could I update the virtual layer with the following simple query:

SELECT * FROM anotherLayer WHERE ID < 10

Answer 1

It should be enough to update the layer data source with an appropriate URI. See the following examples involving 2 layers from Natural Earth (airports and countries) and 2 different queries for each layer.

pathAirports = u'/docs/geodata/world/ne_10m_airports.shp'
pathCountries = u'/docs/geodata/world/ne_10m_admin_0_countries.shp' 

queryAirports="SELECT * FROM airports"
queryAirports2="SELECT * FROM airports WHERE type='major'"
queryCountries="SELECT * FROM countries"
queryCountries2="SELECT * FROM countries WHERE SUBREGION='South America'"

layer = QgsVectorLayer(
            "?layer=ogr:{}:airports&query={}".format( pathAirports, queryAirports ),
            "Airports",
            "virtual" )
QgsMapLayerRegistry.instance().addMapLayer( layer )

layer.setDataSource(
            "?layer=ogr:{}:airports&query={}".format( pathAirports, queryAirports2 ),
            "Some Airports", 
            "virtual" )

layer.setDataSource(
            "?layer=ogr:{}:countries&query={}".format( pathCountries, queryCountries ),
            "Countries", 
            "virtual" )

layer.setDataSource(
            "?layer=ogr:{}:countries&query={}".format( pathCountries, queryCountries2 ), 
            "Some countries", 
            "virtual" )

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However, there seems to be a bug with Virtual Layers that doesn't allow you to select features properly using canvas tools. For instance, after running the last line above, I cannot select Brasil using the select tool (it keeps selecting Argentina!). I've confirmed this on QGIS v2.14.8 (GNU/Linux), QGIS 2.16.3 (Windows 7), and a recent QGIS build v2.99 (GNU/Linux). This is not a bug due to the PyQGIS code above, in fact, creating the virtual layer from QGIS GUI (either from DB Manager or Manage Layers Toolbar) I get the same result. Can you confirm such behavior?