What is the difference between a fresh install and an upgrade with respect to advantages and disadvantages of one approach over another? Or put another way, whether one should upgrade or do a fresh install.
The following are salient features in upgrade or fresh installation and are self explanatory in terms of advantage of one over another, depending on one’s specific need:
*The upgrade process retains the tuning parameters in paramdb which a fresh install will not. It will also retain the existing config files and hint file. If preferring to do an install, one needs to bring over these contents from existing installation to the new installation.
*The upgrade process retains the monitoring scripts but that is no certainty that those scripts will work in new environment and need to be tested. If doing a fresh install, these files need to be brought over from existing installation to the new installation.
*For some versions the upgrade is simply not possible and a fresh install needs to be done because of no upgrade path possible from that version to the newer version. For example, you can not upgrade from SharePlex version 5.x to version 8.x.
*Fresh install will require an activation but upgrade will not.
*If multiple Shareplex instances are involved, then upgrade provides an option to upgrade all variable directories in one simple step. A fresh installation will require such variable directories to be tarred up from the first variable directory created as a part of fresh installation. The procedure is described in Shareplex Administrator Guide Chapter titled "Running multiple instances of Shareplex".
*A fresh install is simple and will not modify the existing Shareplex instance so if one decides to rollback to older version (subject to some limitations), it is easy.
*If changing Shareplex OS user or group, a fresh installation may be a better option.
*If Shareplex schema for the database is retained during fresh install (by specifying the earlier SharePlex schema during running of ora_setup), then all customized info such as internal table entries for Horizontal Partitioning or DDL filtering (the latter is only applicable for SharePlex 7.6 or up) will be retained. Otherwise these will have to be recreated. This is not an issue in upgrade.