If the Ola Hallengren index maintenance solution is installed onto a server which already has compression applied to several of the indexes, will the script respect the current compression level when rebuilding the corresponding index?
Yes - I don't see how Ola's script could possibly alter the existing compression level of an index.
If you look at the source for Ola's Index Maintenance, you will not see the word
COMPRESSION anywhere. In order to alter the compression level, his script would actually have to have the word
COMPRESSION in it.