Horton

Re: Add support for AT LOCAL

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Vik Fearing <vik@postgresfriends.org>
Cc: cary huang <hcary328@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2023-09-29T07:27:52Z
Lists: pgsql-hackers 
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

Commits

  1. Dodge a compiler bug affecting timetz_zone/timetz_izone.

  2. Back-patch test cases for timetz_zone/timetz_izone.

  3. Add regression test coverage for timetz_izone().

  4. Add support for AT LOCAL

  5. doc: Mention timezone(zone, time) in section for AT TIME ZONE

  6. Use HASH_BLOBS for xidhash.