The total persisted size of data for a map/reduce script is not allowed to exceed 50MB. This includes the amount of search results stored.

In a search result, each key and the serialized size of each value is counted towards the total size. Note that value size is proportional to the number of search result columns in a result set.

During the map or reduce stage, the total size is a measure of the amount of keys and values to be processed. After a key or value is processed, it is not counted towards the total size.

If the limit is exceeded, that instance of a map/reduce task fails and a STORAGE_SIZE_EXCEEDED error is thrown.