Currently, I have a vector layer with polygons in it and another layer with points. There is a column with an exact time stamp in the points layer; I would like to determine the time stamp for the earliest point in each polygon (note - some polygons might not have a point in it.) There are probably 20,000-25,000 polygons in this layer, so unfortunately I can't do this polygon-by-polygon. Once I've identified the earliest point, I'd then like to create a column in the polygon with its time stamp. Any intuition on how I can do this?

  • This is basic tabular statistics. You can join on the fly or intersect once, then SELECT min(datecol) with a GROUP BY of polygon ID.
    – Vince
    Commented Feb 14, 2023 at 14:15
  • Thanks for the reply. I just added another sentence toward the end of my question. From there, how could I then create a column in the polygon with the time stamp of the earliest point? Commented Feb 14, 2023 at 14:22

1 Answer 1


You can easily do this by adding a virtual field to your Polygon layer:


This will handle finding the minimum timestamp within each given polygon and setting it as an attribute for each polygon

Polygons with no points inside will have a NULL attribute

Applying it to a layer where I search theRandom points minimum Id attribute value, assigned to an earliest field.

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Points labels are their Id, Polygon label in red is the earliest field attribute

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Changes to either layer are handled dynamically:

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