Thanks a lot for the answer. I see a lot of people discussing so many things so I thought my email would have been ignored by those with a lot coming in already. Thanks for the enlightenment.
On Fri, Nov 19, 2010 at 10:51 PM, Vaibhav Kaushal <vaibhavkaushal123@gmail.com> wrote: > Is no one ready to help on this? :(
Apparently, no one is ready to drop what they are doing to immediately answer your email before all the other ones they need to answer, but I wouldn't infer from that that no one wants to help. It doesn't seem very realistic to me to expect a 12-hour turnaround on free support, but what do I know?
With regards to your question, for each type of plan node, there is an associated "plan state" node. This is an important distinction because, IIUC, plans can be reused, so plan state contains the information that might need to be reset on each run. Scan state is just a plan state node for a scan node. I believe a tuple projection is what you get when you do something like SELECT generate_series(1,10) FROM tbl - the set-returning function has to be "projected" in multiple tuples. EState I could use some hints on myself. A qual is a filter condition, e.g. in SELECT * FROM tbl WHERE x = 1, the "x = 1" part is a qual. It's helpful to grep src/include for the structures in question; the information they contain often helps to understand their purpose.