2017-01-25 21:06 GMT+01:00 Jim Nasby <jim.na...@bluetreble.com>: > On 1/23/17 11:38 PM, Pavel Stehule wrote: > >> >> Instead of paralleling all the existing namespace stuff, I wonder if >> it'd be better to create explicit block infrastructure. AFAIK >> PRAGMAs are going to have a lot of the same requirements (certainly >> the nesting is the same), and we might want more of this king of >> stuff in the future. (I've certainly wished I could set a GUC in a >> plpgsql block and have it's settings revert when exiting the block...) >> >> >> I am not sure if I understand. ?? Setting GUC by PRAGMA can work - the >> syntax supports it and GUC API supports nesting. Not sure about >> exception handling - but it should not be problem probably. >> >> Please, can you show some examples. >> > > From a code standpoint, there's already some ugliness around blocks: > there's the code that handles blocks themselves (which IIRC is responsible > for subtransactions), then there's the namespace code, which is very > separate even though namespaces are very much tied to blocks. Your patch is > adding another layer into the mix, separate from both blocks and > namespaces. I think it would be better to combine all 3 together, or at > least not make matters worse. So IMHO the pragma stuff should be part of > handling blocks, and not something that's stand alone. IE: make the pragma > info live in PLpgSQL_stmt_block. >
I don't think it is fully correct - the pragma can be related to function too - and namespaces can be related to some other statements - cycles. Any PLpgSQL_stmt_block does some overhead and probably we want to build a fake statements to ensure 1:1 relations between namespaces and blocks. I didn't implement and proposed third level of pragma - statement. For example the assertions in Ada language are implemented with pragma. Currently I am not thinking about this form for Postgres. The cursor options is better stored in expression - the block related GUC probably should be stored in stmt_block. The pragma is additional information, and how this information will be used and what impact will be on generated code depends on pragma - can be different. > GUCs support SET LOCAL, but that's not the same as local scoping because > the setting stays in effect unless the substrans aborts. What I'd like is > the ability to set a GUC in a plpgsql block *and have the setting revert on > block exit*. I am think so it is solvable. Regards Pavel > > -- > Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX > Experts in Analytics, Data Architecture and PostgreSQL > Data in Trouble? Get it in Treble! http://BlueTreble.com > 855-TREBLE2 (855-873-2532) >
