On 08/07/2019 16:23, Andrew Gierth wrote: >>>>>> "Tom" == Tom Mercha <mercha_t@xxxxxxxxxxx> writes: > > Tom> Hi All > > Tom> As we know, a query goes through number of stages before it is > Tom> executed. One of these stages is query optimization (QO). > > That's not really true at all. One of the stages is query _planning_, > which takes the (rewritten) query as input and converts it to something > that the executor can take action on. There isn't actually any separate > "optimization" phase. > Hi I was just loosely speaking - I am merely referring to the concept that a query can be optimized vs unoptimized. Of course it follows that we have a phase or a subset of stages which are responsible for this purpose.
