Re: Add support for AT LOCAL

On Sat, Sep 23, 2023 at 12:54:01AM +0200, Vik Fearing wrote:
> On 9/22/23 23:46, cary huang wrote:
>> I think this feature can be a useful addition in dealing with time
>> zones. I have applied and tried out the patch, The feature works as
>> described and seems promising. The problem with compilation failure
>> was probably reported on CirrusCI when compiled on different
>> platforms. I have run the latest patch on my own Cirrus CI environment
>> and everything checked out fine.
>
> Thank you for reviewing!

+ | a_expr AT LOCAL %prec AT
+ {
+ /* Use the value of the session's time zone */
+ FuncCall *tz = makeFuncCall(SystemFuncName("current_setting"),
+ list_make1(makeStringConst("TimeZone", -1)),
+ COERCE_SQL_SYNTAX,
+ -1);
+ $$ = (Node *) makeFuncCall(SystemFuncName("timezone"),
+ list_make2(tz, $1),
+ COERCE_SQL_SYNTAX,
+ @2);

As the deparsing code introduced by this patch is showing, this leads
to a lot of extra complexity. And, actually, this can be quite
expensive as well with these two layers of functions. Note also that
in comparison to SQLValueFunctions, COERCE_SQL_SYNTAX does less
inlining. So here comes my question: why doesn't this stuff just use
one underlying function to do this job?
--
Michael