The string literal is preceded by the character set name, prefixed with an underscore character: ”, will continuously update rows, over and over, and give the impression that the server has hung.Quirks like this can affect any data-changing DML operations, most often when the selection conditions involve a subquery.
filtered positional operator to define an identifier, which you then reference in the array filter documents.
You cannot have an array filter document for an identifier if the identifier is not included in the update document.
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clause, the assignment phrases, containing the columns with the values to be set, are separated by commas.
In an assignment phrase, column names are on the left and the values or expressions containing the assignment values are on the right. A column name can be used in expressions on the right.
Cases have been reported where sort order interferes with expectations, without involving a subquery.
It happens because, in the execution layers, instead of establishing a stable “” and then executing the data changes to each set member, DML statements use implicit cursors for performing the operations on whatever row currently meets the conditions, without knowledge of whether that row formerly failed the condition or was updated already.
), the operation uses the collation specified for the collection.
If no collation is specified for the collection or for the operations, Mongo DB uses the simple binary comparison used in prior versions for string comparisons.
Always do this after the insert, since it's faster to add the index in bulk than to update the index as you write into the temp table.