2018-03-05 16:19 GMT+01:00 Pavel Luzanov <[email protected]>: > On 05.03.2018 18:01, Pavel Stehule wrote: > > > It is most correct when you thinking about it. > > 1. :xx is out of SQL syntax, so can by safely used. There is not risk of > unwanted usage. > > But there is absence of wanted usage too. >
How much strong and often? The parser of SQL in psql is not nice - and I understand so nobody would to complicate syntax. Current design is SAFE and good enough. The problem is not is a evaluation, but in DO implementation. > > 2. but string literal can contain :xxx symbols and not necessary it means > so it should be usage of psql variable - so additional syntax for disabling > evaluation should be necessary > > Yes and Oracle sqlplus (I khow than you know this tool) has special > command to control this: set define ... > > > Unfortunately DO command is half baked - and doesn't support parameters. I > am working on schema variables and I hope it will be a solution of this > issue: > > CREATE VARIABLE var as integer; > > LET var = :psqlintvar; > > DO $$ > BEGIN > RAISE NOTICE '%', var; > END; > $$; > > > It will be great. I already commented it in your blog. > I am slowly working on prototype. The work is simple, when variables are just scalars. But it is much harder, when we allow composite variables. When prototype will be done, I invite any cooperation - there are lot of question - and one very hard - where and how the variable should be stored (values) - now I have workaround, but it is pretty ugly code. CREATE VARIABLE x INT; LET x = 10; BEGIN; DROP VARIABLE x; ROLLBACK; SELECT x; -- should be 10 .. for this situation, the PostgreSQL internal caches are not prepared Regards Pavel > > ----- > Pavel Luzanov > Postgres Professional: http://www.postgrespro.com > The Russian Postgres Company > >
