Hi, (CCing -hackers)
On 2018-09-24 12:22:28 -0700, legrand legrand wrote: > I have found that explain on tables with many (hundreds) columns > are slow compare to nominal executions. Yea, colname_is_unique() (called via make_colname_unique()) is essentially O(#total_columns) and rougly called once for each column in a select list (or using or ...). IIRC we've hit this once when I was at citus, too. We really should be usign a more appropriate datastructure here - very likely a hashtable. Unfortunately such a change would likely be a bit too much to backpatch... Greetings, Andres Freund
