This PR actually does 2 things (sending in 1 PR to prevent merge-hell as both changes are on the populate command);
Indexing hundreds of thousands of items takes a long time now and runs out of memory. This should be done in batches to prevent errors. Note; this might take a bit longer, but batch size is adjustable.
The index command now requires a parameter and can only index on a per-entity basis. While the schema show command knows which entities are indexable. The command will need to index all of these documents when no argument is given.
This PR actually does 2 things (sending in 1 PR to prevent merge-hell as both changes are on the populate command);