I am reading the O'Reilly CouchDB book. I am puzzled by the reduce/re-reduce/incremental-MapReduce part on page 64. Too much is left to rhetory in the O'Reilly book with the sentence


  If you're interested in pushing the ede of CouchDB's incremental reduce functionality, have a look at Google's paper on Sawzall, ...


If I understand the word "incremental" correctly, it refers to some sort of addition -operation in the B-tree data structure. I cannot yet see why it is somehow special over typical map-reduce, probably not yet understanding it. In CouchDB, it mentions that there is no side-effects with map function - does that hold true with reduce too?

Why is MapReduce in CouchDB is called "incremental"?

Helper questions


Explain the quote about incremental MapReduce with Sawzall.
Why two terms for the same thing i.e. reduction? Reduce and re-reduce?


References


A Google paper about Sawzall.
Introduction to CouchDB views in the CouchDB wiki and a lot of blurry blog references.
CouchDB O'Reilly book



Question: Doctors working on Shabbat
Answer: First of all, being a doctor and healing the sick is not considered a Malacha (work on Shabbos). It is considered a Chachma, a gift, not a trade. See Rambam Hichos Refuah.

There is a fantastic Steera (contradiction) found in the Rambam which points this out. In Hilchos Shabbos, the Rambam holds that one is prohibited from carrying an amulet, since (medically speaking) they are of no use. However, in Hilchos Refuah, Rambam states that one can use (carry) an amulet since the ill person believes in this amulet (an amulet must be considered Mumcha, one which has been proven by healing the sick already), and healing is 60% in the mind, therefore the ill will be healed. As you can hear, the Rambam didn't sound like he was in favor of using tricks or the like. But if it works, any port in the storm!

Next question, is one allowed to transgress the Shabbos to heal a Goy? Technically no. However the Chachamim stressed that if they knew this they would kill us, therefore it is in our best interest to heal them ("משום איבה"). I fear to add this but Halacha is just that.

So, can one heal an animal on Shabbos? Basically no. However, one can make the animal comfortable until a doctor can administer to the animal. There is a wonderful book Sefer Tsar Balay Chaim by R' Itchak Nachman Eshkoli written in the last 10 years which deals with anything &amp; everything to do with animal suffering. My son-in-law used this while writing a paper on Feeding Animals on Shabbos while in YU. I highly recommend this sefer to anyone who has an animal, especially since Tzar Balay Chaim is a Torah Issur and it is important to know what one can or shouldn't do.

Medical Halacha is well researched by the likes of Dr. Fred Rosner, Rabbi Dr. Abraham S Abraham (Nishmas Avraham), and many more. There are many Rabbis who write on medical halacha. Although that is a subject for another time indeed!