July 24, 2008 at 9:07 pm
Comments posted to this topic are about the item Page Compression
July 25, 2008 at 2:27 pm
Since SQL Server 2005 did not have Page Compression (as I know it), it wasn't too much of a jump to know this was about 2008 and not 2005. It would be nice to have these questions placed in categories that designate the release. For example, this one would be 2008 only... the ";with numbered... partition by..." would be 2005 and up... 2 cents. BTW, thanks to Linchi Shea for explaining this one well.
Jamie
December 7, 2010 at 1:40 pm
BoL is wonderfully ambiguous on this. One can go with the definition that says Page Compression is the whole thing, including Row Compression, or one can go with the conflicting statement
As data is added to the first data page, data is row-compressed. Because the page is not full, no benefit is gained from page compression. When the page is full, the next row to be added initiates the page compression operation.
that's on the very same BoL page as the statement that Page Compression consists of Row Compression, Prefix Compression, and Dictionary Compression. The conficting version seems to be confirmed by the statement (on a different page) that non-leaf index pages are not page compressed but are row compressed. So faced with this question one has to guess which of the two contradictory MS definitions of page compression the questioner believes - there is no rational way of choosing one over the other.
I don't think questions with that degree of unanswerableness should be put int QOTD except perhaps in the humour category.
Tom
September 15, 2014 at 7:08 pm
crussell-931424 (9/15/2014)
I've never heard of postfix compression.
Then find yourself a good textbook on the evolution of present tense plural verb endings in Romance languages and read it. You'll find lots of compresssed postfixes there (eg French "tenons" is much more compressed than Spanish "tenemos" - the Spanish has not contracted the original Latin "tenemus", merely changed a vowel, but the French is much more compressed - and as we are looking at something on the root ten- what is different is the postfix, "emos" or "ons", French has contracted the two syllables of the postfix to one).
Of course in a purely database context, the term "postfix compression" rarely turns up; I don't recall ever seeing it in a computer context except as one of the wrong answers to this question.
Tom
September 15, 2014 at 7:28 pm
TomThomson (12/7/2010)
BoL is wonderfully ambiguous on this. One can go with the definition that says Page Compression is the whole thing, including Row Compression, or one can go with the conflicting statementAs data is added to the first data page, data is row-compressed. Because the page is not full, no benefit is gained from page compression. When the page is full, the next row to be added initiates the page compression operation.
that's on the very same BoL page as the statement that Page Compression consists of Row Compression, Prefix Compression, and Dictionary Compression. The conficting version seems to be confirmed by the statement (on a different page) that non-leaf index pages are not page compressed but are row compressed. So faced with this question one has to guess which of the two contradictory MS definitions of page compression the questioner believes - there is no rational way of choosing one over the other.
I don't think questions with that degree of unanswerableness should be put int QOTD except perhaps in the humour category.
A Microsoft employee has mentioned to me in their lab tests that selecting Page Compression for all tables is a good start rather than deciding to pick and choose between row or page for a table. That person also mentioned that on average pretty much everything got better, with some exceptions... in those cases you just have to work those out/fix. But the overall improvements outweighed the negative.
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