To allow the query engine to optimize queries, |and-or| handles errors as follows:
- If any expression supplied to |and-or| would cause an error when evaluated alone, the |and-or| containing the expression may cause an error but an error is not guaranteed.
- An expression supplied after the first expression supplied to |and-or| may cause an error even if the first expression evaluates to |true-false|.
For example, the following query always produces an error if $x is
0:
db.example.find( {
$expr: { $eq: [ { $divide: [ 1, "$x" ] }, 3 ] }
} )The following query, which contains multiple expressions supplied to
|and-or|, may produce an error if there is any document where $x
is 0: