Thanks for your comments and indices !
I have noticed also that the size of M1 history file, eur/usd from 01.01.2010 to 01.01.2011 is abnormally small ( 50 %) with respect to sizes of similar ones for 01.01.2011 – 01.01.2012 and 01.01.2012 – 01.01.2013. Is it a market info which was too particular this year having thus smaller number of ticks, or some gaps were present in the downloaded file ?
