On Thu, Sep 23, 2021 at 5:34 AM Joe Wildish <j...@lateraljoin.com> wrote: > Regarding the deparse-and-reparse --- if I understand correctly, the core > problem is that we have no way of going from a node tree to a string, such > that the string is guaranteed to have the same meaning as the node tree? (I > did try just now to produce such a scenario with the patch but I couldn't get > ruleutils to emit the wrong thing). Moreover, we couldn't store the string > for use with SPI, as the string would be subject to trigger-time search path > lookups. That pretty much rules out SPI for this then. Do you have a > suggestion for an alternative? I guess it would be go to the planner/executor > directly with the node tree?
I think hoping that you can ever make deparse and reparse reliably produce the same result is a hopeless endeavor. Tom mentioned hazards related to ambiguous constructs, but there's also often the risk of concurrent DDL. Commit 5f173040e324f6c2eebb90d86cf1b0cdb5890f0a is a cautionary tale, demonstrating that you can't even count on schema_name.table_name to resolve to the same OID for the entire duration of a single DDL command. The same hazard exists for functions, operators, and anything else that gets looked up in a system catalog. I don't know what all of that means for your patch, but just wanted to get my $0.02 in on the general topic. -- Robert Haas EDB: http://www.enterprisedb.com
