MapReduce related patterns

Mon, 26 Sep 2011 21:16:15 +0000

Here’s a list of possible MapReduce related patterns I’ve been thinking about:

map-update: update each mapped document and emit its updated or original version;
map-delete: delete each mapped document;
map-reduce-map: map results of a map-reduce;
map-map: map results of a map;
map-recurse: apply recursion to the mapping function until a stop condition occurs;
any combination of patterns, e.g., map-reduce-map-update.

Example usage:

get the e-mail address of every customer with a negative balance: map-reduce-map. First, map-reduce to get the aggregate balance for each customer, then map again to get only customers with negative value and emit their e-mail address;
delete all documents older than one month: map-delete. First, map to get all documents older than one month and then delete each one;
get a list of documents and mark them as read: map-update. First, map to get the list of documents according to a given criteria, then update each document marking it as read;
and so on…

Pattern on Bruno Pedro