From: | Kerem Kat <keremkat(at)gmail(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
Subject: | (PATCH) Adding CORRESPONDING to Set Operations |
Date: | 2011-10-19 13:01:09 |
Message-ID: | CAJZSWkWN3YwQ01C3+cq0+eyZ1DmK=69_6vryrsVGMC=+fWrSZA@mail.gmail.com |
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Lists: | pgsql-hackers |
Adding CORRESPONDING to Set Operations
Initial patch, filename: corresponding_clause_v2.patch
This patch adds CORRESPONDING clause to set operations according to
SQL20nn standard draft as Feature F301, "CORRESPONDING in query
expressions"
Corresponding clause either contains a BY(...) clause or not. If it
doesn't have a BY(...) clause the usage is as follows.
SELECT 1 a, 2 b, 3 c UNION CORRESPONDING 4 b, 5 d, 6 c, 7 f;
with output:
b c
-----
2 3
4 6
i.e. matching column names are filtered and are only output from the
whole set operation clause.
If we introduce a BY(...) clause, then column names are further
intersected with that BY clause:
SELECT 1 a, 2 b, 3 c UNION CORRESPONDING BY(b) 4 b, 5 d, 6 c, 7 f;
with output:
b
--
2
4
This patch compiles and tests successfully with master branch.
It has been tested only on Pardus Linux i686 ( Kernel 2.6.37.6 #1 SMP
i686 i686 i386 GNU/Linux)
This patch includes documentation and add one regression file.
This patch addresses the following TODO item:
SQL Commands: Add CORRESPONDING BY to UNION/INTERSECT/EXCEPT
Best Regards,
Kerem KAT
Attachment | Content-Type | Size |
---|---|---|
corresponding_clause_v2.patch | text/x-patch | 37.0 KB |
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