On Thu, May 20, 2021 at 09:14:45PM +0530, Bharath Rupireddy wrote: > On Thu, May 20, 2021 at 7:52 PM Bernd Helmle <maili...@oopsware.de> wrote: >> "mv" looks like a very common alias (i use it all over the time when >> testing or playing around with materialized views, so i'm wondering why >> i didn't see this issue already myself). So the risk here for such a >> collision looks very high. We can try to lower this risk by choosing an >> alias name, which is not so common. With a static alias however you get >> a static error condition, not something that fails here and then. > > Another idea is to use random() function to generate required number > of uint32 random values(refresh_by_match_merge might need 3 values to > replace newdata, newdata2 and mv) and use the names like > pg_temp_rmv_<<rand_no1>>, pg_temp_rmv_<<rand_no2>> and so on. This > would make the name unguessable. Note that we use this in > choose_dsm_implementation, dsm_impl_posix.
I am not sure that I see the point of using a random() number here while the backend ID, or just the PID, would easily provide enough entropy for this internal alias. I agree that "mv" is a bad choice for this alias name. One thing that comes in mind here is to use an alias similar to what we do for dropped attributes, say ........pg.matview.%d........ where %d is the PID. This will very unlikely cause conflicts. -- Michael
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