Hi - In the 10.2 Doc Review of the Tuning Guide http://wiki.apache.org/db-derby/TuningTenTwo there is this comment:
In the file http://db.apache.org/derby/docs/dev/tuning/rtuntransform472.html there is a mention of rewriting queries: "Users can work around this possibility by writing the query like this (which is not optimizable):(country... ) LIKE ?". But this does not mention the rationale for doing so, which could be benefical for the users in understanding the transformation. One thought is that specifying "(country || '')" disables the transformation because "(country || '')" evaluates to a Concatenate node instead of a ColumnReference, which makes the expression "not optimizable" and thus the transformation is skipped. Does anyone have any additional information as to why "(country || '')" should be specified? Thanks! -- Laura Stewart
