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Order entities by insertion #6408

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merged 3 commits into from
Sep 11, 2024
Merged

Order entities by insertion #6408

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da0b4b9
Order entities by index
seadowg Sep 11, 2024
3aac55c
Improve index test so that it now fails because of ordering
seadowg Sep 11, 2024
4e998fd
Fix ordering
seadowg Sep 11, 2024
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4 changes: 3 additions & 1 deletion ...app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,7 @@ class DatabaseEntitiesRepository(context: Context, dbPath: String) : EntitiesRep
SELECT *, i.$ROW_ID
FROM $list e, ${getRowIdTableName(list)} i
WHERE e._id = i._id
ORDER BY i.$ROW_ID
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I don't think we strictly need the ORDER BY here and in the other queryWithAttachedRowId overload and I can't work out a way to test it (I think the query is structured so that it always happens to works out). I feel safer having it there though so.

""".trimIndent(),
null
)
Expand All @@ -301,6 +302,7 @@ class DatabaseEntitiesRepository(context: Context, dbPath: String) : EntitiesRep
SELECT *, i.$ROW_ID
FROM $list e, ${getRowIdTableName(list)} i
WHERE e._id = i._id AND $selectionColumn = ?
ORDER BY i.$ROW_ID
""".trimIndent(),
arrayOf(selectionArg)
)
Expand All @@ -325,7 +327,7 @@ class DatabaseEntitiesRepository(context: Context, dbPath: String) : EntitiesRep

writableDatabase.execSQL(
"""
CREATE TABLE ${getRowIdTableName(it)} AS SELECT _id FROM $it;
CREATE TABLE ${getRowIdTableName(it)} AS SELECT _id FROM $it ORDER BY _id;
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As far as I understand it, _id should have the same order as insertion.

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There is a potential issue with this assumption: if we delete some entities, their IDs might be reused. While this shouldn't occur under normal circumstances, once we reach the maximum possible ID value of 9223372036854775807, IDs will start to be reused. However, this number is large enough that we don't need to worry about it for now I guess. Do you agree @lognaturel?

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Ahh the table gets recreated every time we add/delete an entity so it won't be and issue.

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Although, as mentioned above, this is not an issue at the moment, it might be a good idea to add a test that serves as documentation hmm?

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@lognaturel lognaturel Sep 11, 2024 •
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Preserving order is a nice to have more than a must have so I think it's ok to leave edge cases untested. It's only a nice to have because the order is not necessarily meaningful currently. Longer-term, we'll need to be able to let users specify a custom sort order.

""".trimIndent()
)
}
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10 changes: 8 additions & 2 deletions collect_app/src/test/java/org/odk/collect/android/entities/EntitiesRepositoryTest.kt
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Expand Up @@ -309,15 +309,21 @@ abstract class EntitiesRepositoryTest {

@Test
fun `#save assigns an index to each entity in insert order when saving multiple entities`() {
val first = Entity.New("1", "Léoville Barton 2008")
val second = Entity.New("2", "Pontet Canet 2014")
/**
* first and second have alphabetically out of order IDs/names here so that any indexing on
* them is tested. We'd likely never see this fail if they were ordered.
*/
val first = Entity.New("2", "B")
val second = Entity.New("1", "A")

val repository = buildSubject()
repository.save("wines", first, second)

val entities = repository.getEntities("wines")
assertThat(entities[0].index, equalTo(0))
assertThat(entities[0].id, equalTo(first.id))
assertThat(entities[1].index, equalTo(1))
assertThat(entities[1].id, equalTo(second.id))
}

@Test
Expand Down