What this patch does - it change a mechanism, how a values of variables are transmitted to SPI. In previous variant values are copied to ParamListInfo before every evaluation of any expression. New mechanism is smarter. It refresh only ROW, REC values when are marked as dirty (when these variables was used). ParamListInfo is dynamically updated when value is assigned to variable.
This patch can significantly reduce a overhead related to preparing parameters - more it cleaning code.
1. There are no problem with patching, regress tests