PostGIS Split Fails With Data Loss

[qgib]

Author Name: Spencer Gardner (@spencerrecneps)
Original Redmine Issue: 20418
Affected QGIS version: 3.4.1
Redmine category:editing

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To reproduce:

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@create table test (@
@ id serial primary key,@
@ geom geometry(linestring,4326)@
@);@

@insert into test (geom)@
@select st_setsrid(st_makeline(st_makepoint(1,2),st_makepoint(3,4)),4326)@
@;@

1. Add layer "test" to map
2. Start editing session
3. Split line into three features with a single split operation
4. Save edits
5. After error is given, quit editing session by discarding changes

What should happen:
Layer saves the three features.

What happens:
Error is given indicating a failure to save edits because of a duplicate key violation. One of the three features is saved,
the other two are deleted from the dataset, despite having discarded all edits when prompted.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• operating_system was changed from Windows to

[qgib]

Author Name: Bernhard Ströbl (Bernhard Ströbl)

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I can reproduce the behaviour (with one of my PosGIS layers)

While splitting I get the following warnings in the PostGIS-Tab of the log
@warning Query: DECLARE qgis_24 BINARY CURSOR FOR SELECT "gid","href1"::text,"href2"::text,"level_name"::text,"gidb"::text,"datum"::text,"nocheinint"::text FROM "myschema"."mytable" WHERE ("gid" = 'nextval(''myschema.mytable_gid_seq''::regclass)') LIMIT 1 returned 7 [ERROR: invalid input syntax for integer: "nextval('myschema.mytable_gid_seq'::regclass)"
WARNING 1 cursor states lost.
SQL: DECLARE qgis_6 BINARY CURSOR FOR SELECT "gid","href1"::text,"href2"::text,"level_name"::text,"gidb"::text,"datum"::text,"nocheinint"::text FROM "myshema"."mytable" WHERE ("gid" = 'nextval(''myschema.mytable_gid_seq''::regclass)') LIMIT 2
Result: 7 (ERROR: invalid input syntax for integer: "nextval('myschema.mytable_gid_seq'::regclass)"
@

gid is an integer field

[qgib]

Author Name: Bernhard Ströbl (Bernhard Ströbl)

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I can save the split features when ticking Evaluate default values on provider side in Project Properties - Data Sources
@spencer: could you check if that works for you?
Nevertheless the issue is still valid as the data is corrupted although Discard changes is chosen.

[qgib]

Author Name: Jan Lippmann (@j-lippmann)

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I can confirm. In my case with polygons.

I think this problem has a relationship with #28251 , because:

1. Step: If i split one feature in only two parts..if i don't save edits..there is no issue
2. Step: If i split another one feature in only two parts...there is a problem with duplicate key violation

BTW: If i save edits after step 1., there is no problem with duplicate key violation

[qgib]

Author Name: Stephen Knox (Stephen Knox)

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I can't reproduce this on 3.5 master - I get three seperate lines after splitting, with no errors

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Stephen Knox wrote:

I can't reproduce this on 3.5 master - I get three seperate lines after splitting, with no errors

The original reporter also confirms?

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• status_id was changed from Open to Feedback

[qgib]

Author Name: Spencer Gardner (@spencerrecneps)

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I'm on vacation for a few more days so I won't be able to confirm until then. I strongly suspect Jan is correct about this being related to #28251 which has been resolved.

[qgib]

Author Name: Jan Lippmann (@j-lippmann)

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My Test with 3.4.3: There is no more issue. I think 32b7d7e solved the problem. Ticket can be closed...

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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• resolution was changed from to fixed/implemented
• status_id was changed from Feedback to Closed