"compress=y" will size the first extent in each table or index to be large enough to hold all of the data in one extent. Don't do it, having everything in one extent will not make it faster, it might cause more fragmentation though. Your export will be less than 45GB. how much less depends on how tightly packed the data is. Why don't you try an export and find out. If you are worried about having enough space for the export then you can pipe the export to gzip.
my database size 45 gb
than i taking full exporting data ....
what is the size of export dump file?
and "compress=y" means reduce size of export file???
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