we are looking to do a table partition in MYSQL RDS running 5.6, table size is large and takes around 6 hours to partition. Can we partition on rds slave and then later promote it to master. is this do able, if not what is best way to partition this large table
First, let's discuss what benefit you will get from partitioning. Please provide
SHOW CREATE TABLE (with the partitioning). Partitioning, in itself, does not provide any performance benefits. Let's see the query/queries that you think will benefit.
pt-online-schema-change is likely to be a way to convert to partitioning with virtually no downtime. But check carefully; there may be restrictions on partitioning.
The manual says nothing about whether you can have replication between a non-partitioned on the master and a partitioned table on the slave. The silence of the manual worries me; there could be issues.