US Patent 8935201 Determining and extracting changed data from a data source

According to certain aspects, a computer system may be configured to obtain information indicating a plurality of groupings of data stored in a data source, the information indicating a number of data items included in each of the plurality of groupings; determine a first grouping of the plurality of groupings including one or more data items that have changed by comparing a first number of data items included in the first grouping and a historical first number of data items included in a corresponding local version of the first grouping; access data items included in the first grouping from the data source; compare the data items included in the first grouping to data items of the corresponding local version of the first grouping to determine which data items have changed; extract the changed data items of the first grouping; and forward the extracted data items to a destination system.