Prior to the advent of the feature of supplemental logging, Shareplex used to lock source tables to gather row chaining info by analyzing the tables. The duration of the lock depended on the size of the table and the amount of row chaining present in the table. With supplemental logging (introduced in Oracle 9i and up and supported by Shareplex in 5.1 and up) there is no need to analyze the tables for obtaining row chaining info. The question is, why do Shareplex still lock the source table, albeit briefly, during activation?
By locking the source table(s) during activation, we ensure that Shareplex does not replicate partial (or open) transactions. So the source tables are still locked briefly during activation on a database with supplemental logging enabled despite no ANALYZE carried out by the activation process.