While working on Migration Bundle, we discovered that current SearchService API does not allow iterating over resultset, i.e. forces loading all rows returned from Doctrine query into PHP's memory.

Doctrine already allows iterating over each row one at a time and it is specifically used for batch processing of entities: https://www.doctrine-project.org/projects/doctrine-orm/en/2.7/reference/batch-processing.html#iterating-results

This will allow operations that require iterating over whole database contents to become faster, since it would limit the number of SQL queries that are required. This is true regardless of whether the query in question would make use of indices. In fact, it is a lot more impactful in cases where sequential table scan is needed by database to present results.

In cases like Migration Bundle it will prevent query collisions from occuring: long running migration generation commands run into risk of some records being omitted or duplicated depending on mid-operation database changes.