values for cached join fields randomely become null when dragging canvas

[qgib]

Author Name: Mathieu Pellerin - nIRV (Mathieu Pellerin - nIRV)
Original Redmine Issue: 17450
Affected QGIS version: master
Redmine category:vectors
Assignee: Paul Blottiere

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I've finally been able to reduce this features going missing issue that's been haunting me for a while now.

When doing multiple joins like this: ```i.e. fields ORIGINAL -> joined fields A linked through a field in ORIGINAL -> joined fields B linked through a joined field in A

*Steps to reproduce*
1. Open the attached join_cache test project
1. When the project opens, start rapidly panning the canvas around (small steps using the mouse's middle button is the easiest way)
1. You'll notice the dark pink polygons going missing after every few pans (see gonebabygone.mp4 video too)

This does not only affect feature rendering, saving the layer (with all its joins) can actually write null values for joined fields B.

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- [join_cache_issue.zip](https://issues.qgis.org/attachments/download/11677/join_cache_issue.zip) (Mathieu Pellerin - nIRV)
- [gonebabygone.mp4](https://issues.qgis.org/attachments/download/11678/gonebabygone.mp4) (Mathieu Pellerin - nIRV)
- [gonebabygone.mp4](https://issues.qgis.org/attachments/download/11679/gonebabygone.mp4) (Mathieu Pellerin - nIRV)

[qgib]

Author Name: Mathieu Pellerin - nIRV (Mathieu Pellerin - nIRV)

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• description was changed from I've finally been able to reduce this features going missing issue that's been haunting me for a while now.

When doing multiple joins (

i.e. fields ORIGINAL -> joined fields A linked through a field in ORIGINAL -> joined fields B linked through a joined field in A

), the values can get lost if the joins are cached.

Steps to reproduce

Open the attached join_cache test project

When the project opens, start rapidly panning the canvas around (small steps using the mouse's middle button is the easiest way)

You'll notice the dark pink polygons going missing after every few pans (see gonebabygone.mp4 video too)

This does not only affect feature rendering, saving the layer (with all its joins) can actually write null values for joined fields B. to I've finally been able to reduce this features going missing issue that's been haunting me for a while now.

When doing multiple joins like this:

i.e. fields ORIGINAL -> joined fields A linked through a field in ORIGINAL -> joined fields B linked through a joined field in A

the values will get lost every now and then when those joins are cached.

Steps to reproduce

Open the attached join_cache test project

When the project opens, start rapidly panning the canvas around (small steps using the mouse's middle button is the easiest way)

You'll notice the dark pink polygons going missing after every few pans (see gonebabygone.mp4 video too)

This does not only affect feature rendering, saving the layer (with all its joins) can actually write null values for joined fields B.

[qgib]

Author Name: Mathieu Pellerin - nIRV (Mathieu Pellerin - nIRV)

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Better video, featuring the reduced test project attached.

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• 11679 was configured as gonebabygone.mp4

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• gonebabygone.mp4 (Mathieu Pellerin - nIRV)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Seems also to not happen in 2.18(?).

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• regression was changed from 0 to 1

[qgib]

Author Name: Paul Blottiere (Paul Blottiere)

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• assigned_to_id was configured as Paul Blottiere

[qgib]

Author Name: Regis Haubourg (@haubourg)

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PR proposed here [[https://github.com//pull/5638]]

[qgib]

Author Name: Paul Blottiere (Paul Blottiere)

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Applied in changeset 333a8e9.

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• done_ratio was changed from 0 to 100
• status_id was changed from Open to Closed