Thanks your reply.
1)The big string ,i mean the string is large enough,about 8-10k
2)I use the SqlServer ( varchar(max) ) to store the string.
3)I just compress common string ,eg.:

my $string = "
aaaaaaaaaaaaaaaaaaaaaaaa  sdfsdf
bbbbbbbbbbb sdfsdfsdf
sdfffffffff                   sdfsdf < tabl> 
sfsdfffffffffffffffffffffffffffffffffffffffffff
...
much and more ....
"
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