how to make queries with logical operators?

[Patrick Maia]

Hi all, imagine I have a database that stores documents like these:

{ "type":"a", "attr1":"value1.1", "attr2":"value2.1"}
{ "type":"a", "attr1":"value1.2", "attr2":"value2.2"}
{ "type":"b", "attr3":"value3"}
{ "type":"c", "attr4":"value4"}

Is there some way to get all docs where type == "a" or  type == "b" doing
just one http request to couchdb?

Thanks,

Patrick Maia