On Fri, Apr 2, 2021 at 02:28:02AM +0800, Julien Rouhaud wrote: > Unless I'm missing something query_string isn't a global variable, it's a > parameter passed to exec_simple_query() from postgresMain(). > > It's then passed to the stats collector to be able to be displayed in > pg_stat_activity through pgstat_report_activity() a bit like what I do for the > queryid. > > There's a global variable debug_query_string, but it's only for debugging > purpose. > > > > I wonder if the query hash > > > should be a global variable too --- this would more clearly match how we > > > handle top-level info like query_string. Digging into the stats system > > > to get top-level info does seem odd. > > The main difference is that there's a single top level query_string, > even if it contains multiple statements. But there would be multiple queryid > calculated in that case and we don't want to change it during a top level > multi-statements execution, so we can't use the same approach. > > Also, the query_string is directly logged from this code path, while the > queryid is logged as a log_line_prefix, and almost all the code there also > retrieve information from some shared structure. > > And since it also has to be available in pg_stat_activity, having a single > source of truth looked like a better approach. > > > Also, if you go in that direction, make sure the hash it set in the same > > places the query string is set, though I am unclear how extensions would > > handle that. > > It should be transparent for application, it's extracting the first queryid > seen for each top level statement and export it. The rest of the code still > continue to see the queryid that corresponds to the really executed single > statement.
OK, I am happy with your design decisions, thanks. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
