Re: How to copy a database

Kevin Brand wrote: > > Why use SQL:UNLOAD or dbexport, which both need filesystem space large > enough to hold your data? Simply use tbunload (v5.x)/onunload (v7.x) to > a tape device and then tbload/onload into the test area. This can be done > across the network to another machine, across instances of Online, or locally > on the production server. The only draw-back I can think of is that during > the unload process, your database will be locked exclusively. > > You may even use the filesystem by 'touch'ing a file and using its name as > the tape device on the command line. > > Try this: > > cd /tmp > mknode mypipe p # a named UNIX pipe ( FIFO ) > > echo "\\n" | onunload -t /tmp/mypipe -b 8192 -s some_large_number database_name & > > onload -t /tmp/mypipe -b 8192 -s same_number -d dbspace_name database_name> > Here you have a file, 'mypipe' that will act as a pipe between the > unloader and the loader. This is somewhat slower than using a tape but > requires very little filesystem space. > > Using tb/onunload and tb/onload is nearly always faster than any other method > because they read and write informix pages in binary format, not rows!!! > > Kevin Brand Do NOT use onload or onunload, since it's not reliable. Don't even use 4MM DAT, because it's even less reliable. A good method to unload a table (or tables for a database) is this : mkfifo fifo dd if=fifo|compress|of=table.unl.Z & echo "unload to fifo select * from table"|dbaccess database After the completion of the unload, you have an unl file in compressed format...Since unl files are text files, the compression rate can rise up to 10:1 (depends on the contents of your columns). If you have online 7.20, try and use the ipload, which loads and unloads table at a terrific speed.... Bye. Valery Fouques - SYSADM Gosport/FRANCE