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When to add what indexes in a table in Rails

... Should I add "index" to all the foreign keys like "xxx_id"? It would be better, because it accelerates the search in sorting in this column. And Foreign keys are something searched for a lot. Since Version 5 of rails the index will be c...
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ObservableCollection Doesn't support AddRange method, so I get notified for each item added, besides

... OnCollectionChanging(ce) If ce.Cancel Then Exit Sub Dim index = Items.Count - 1 For Each i In collection Items.Add(i) Next OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, collection, index)) End S...
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MySQL Cannot drop index needed in a foreign key constraint

...NIQUE field to encompass that new column. I'm trying to remove the current index but keep getting the error MySQL Cannot drop index needed in a foreign key constraint ...
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Access index of the parent ng-repeat from child ng-repeat

I want to use the index of the parent list (foos) as an argument to a function call in the child list (foos.bars). 6 Answer...
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Prepend a level to a pandas MultiIndex

I have a DataFrame with a MultiIndex created after some grouping: 5 Answers 5 ...
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passing 2 $index values within nested ng-repeat

... which calls the relevant controller for that menu item by passing in the $index to let the app know which one we need. However I need to also pass in the $index from the outer ng-repeat so the app knows which section we are in as well as which tutorial. ...
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MySQL - why not index every field?

Recently I've learned the wonder of indexes, and performance has improved dramatically. However, with all I've learned, I can't seem to find the answer to this question. ...
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E11000 duplicate key error index in mongodb mongoose

...evant documentation for this: If a document does not have a value for the indexed field in a unique index, the index will store a null value for this document. Because of the unique constraint, MongoDB will only permit one document that lacks the indexed field. If there is more than one document wi...
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How to remove “index.php” in codeigniter's path

How do I remove the "index.php" sticking out in every path in codeigniter somewhere in the center? I want clean non index.php-fied URLs ? ...
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Do I need to create indexes on foreign keys on Oracle?

... The foreign key constraint alone does not provide the index on Oracle - one must (and should) be created. share | improve this answer | follow ...