Peter Lipa wrote: > > Hi root talkers, > > What does the error message: > "mmzip: output buffer too small for in-memory compression" > mean? > > I get it when filling a tree with several separate branches. > Increasing the buffer size (from default 32000) to 128000 did not help. > > What do I have to do to get rid of this message and to compress properly? > Could you send me an example of small macro reproducing this problem? > Also, I noticed when the buffsize is bigger than the whole event series > (so that only one buffer(Basket) per branch is used) the branch is > NOT compressed at all. Is that intentional? > The current buffer in memory is not reported to be compressed by TTree::Print. The buffer however will be compressed when you save the Tree header on the file. > I also wondered what the compression levels 3-9 mean?? > I found nothing in the docu and can't see any noticeable effect. > So why are they implemented and when/how to use them? > Compression levels 3->9 show little gain in space in general (this is data dependent). In particular, with Root trees, when branches contain homogeneous data, the higher level compression levels will not give additional advantages. they just take more time. Rene Brun
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