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Thu, 09 Aug 2018 14:35:58 -0700 (PDT) Subject: Re: Typo in doc or wrong EXCLUDE implementation To: Bruce Momjian , KES Cc: Tom Lane , PostgreSQL-development References: <153121527691.1408.5686988620817799073@wrigleys.postgresql.org> <20180807173659.GD7297@momjian.us> <31616681533725753@sas1-d856b3d759c7.qloud-c.yandex.net> <20180808130040.GA2611@momjian.us> <12107.1533736288@sss.pgh.pa.us> <37593701533809465@sas1-87f9feb8d943.qloud-c.yandex.net> <20180809190913.GB14011@momjian.us> From: Vik Fearing Openpgp: preference=signencrypt Autocrypt: addr=vik.fearing@2ndquadrant.com; prefer-encrypt=mutual; keydata= xsFNBFg9q8kBEADfBQMKbYmvL7k4D4ghRYon0lMRf9c+dADesMGsBh5SYTK1/t4S4iCfbc8d QUCyJWSiJYkT1MZNSywbr3hNahZ7qAN0y4kvGNUIxXJGcza5qH5gHQYFrpB/IDoZcZ5/l260 Y5roqQos7kimpALNrl2cXWkR98Z9FWZOocImzdBnKV+qHzD9ZCPISPqR92N67gPqLD4YNx5Y T4NkT2N2nYZlyvv6X3t5/haLWpSLTJ/7ESD6jwTs7Ok4meLidSqr8U25p/L4mb+pscR6l5Hq aJXagW9oQ0uI50Wlri1GeE/JTqaURxfOCWBE3RzrRdhH0HYMOz49gLqba0s4eBlMw18R0OWt TD4mRnpD41X4aaSrMEqm2xXZAa8T+UFlQXWliMvFJ4rQhAogPLN9yI93FDy5pqJdtu3T/mJu HycJfiJHtgGVP8bsMQdg5X4kNWO2LnerJQiO+cYambgb5RWBS3byjO8f05sIXQxIR1nLdGEY 7Cy5/eIN6+qRA3kpRjfQ2QOlEKxVWNLu9t+xGphRi6TidZWnhHRwfCkeelR9R4niubLQPirl /XvToUtm0opXBHbVxTVblM0i7z+x9tnQUCa1f710pnJ/LRqE2Se/JPbEeg5JH4MLLGdr8uxf fv9E8dJVvmTRIWOJFNFnd9e3b9K6I/ek+ysVFsNrKnP9dS4R0QARAQABzSBWaWsgRmVhcmlu ZyA8dmlrQDJuZHF1YWRyYW50LmZyPsLBfQQTAQgAJwUCWD2ryQIbIwUJCWYBgAULCQgHAgYV CAkKCwIEFgIDAQIeAQIXgAAKCRBzOWT4unEhz0W+D/0ZqG/7SmWxSPSm3IcwQaGvxKIE/XFv jZ5USS6W1U/Ttq8qXnJbWOTzEKl6NVQcAuAIAYdvOjwrDDR9SMSMPvHmd7LniOZ4/+V2rdLj fOXzExI+1yJ1TYv1pGTgt5ZmjARIvge942iEYHQey5pavoNI1/C9V0RLuh2yS6dLax21295V OFOhQD11mDJLJ8c/ILVpadqt90V9bQzBWycPOjnwjhxD4kVXMjihnl54EuMp08UW6OTCP4ux /SxJFfTM1WDr+GDk7RgsG3bJfwftdUP2Qc8drwu0LAT41edmaigFGM1RMKeBWeo5Tdcm/Wmo uDeLJwL+CGvEZEjNrLxoXBhuRcv+9m5eYOafqewKgZXTmeZImbk75Jp502LCQHXhdatr9O8a KKjmkKqz+uPOV+4qsvqXdMCCFWb15/Pd/a8ffPMRwq6ebDOPYXJUkGqc65tSlf0gRxfIKof3 gO3TevZ0U1nc7kBa/QNe2QN6RC24+GbyJNEvQ6g2ZbBddffiuYZElsGM3+yiM6jz2RWG4uLQ /Qjw6ZwhNUCOepVa3SsLkSE0HN2M2emN8exQIdJw37IiKIsZPPFa+J3netLfXB4F+/BnwVqK GW8eaLYQWQYRBPTMKgLCqGDCgNIB8cVG7zmx7zYDPXNEwKPfcGSkixfQJxgq1InWDyVg2qwU TP0iVM7BTQRYPavJARAAsdzHCSxLnqy1UW0qNhJoZaIkSbQQ6Bjqgfo4KZKvt2eBe363ubgw 5j6VCfpBpOSJYQrOadY7GOKw0m8iwtr1bvrNg/7SoqfwoKLBTvuxo5WsUD9e8f/Hy1CoMz/3 o1qAvBiQK+MnZvmgtwvwqWpx/g+H2uH8aPttNC1x9lO866o4JtoVWumi01si6KKjO+ZNazPi n9a0JW4OVeLxhIy0OnrE4KMOrnHZlJPIdGP36dtFMK9tyqQ3z3zOp/HN+3mrQZAphH/2idLK wRZURPpisvy3HES9yN/JAWtPEYB0OAhKGJhgLDue08zM8FRNa5ldc/oJCqMEC8D5bh6g3LCz uIM11hOMD8OJNX1lGnzdicBLMghUfhtAJ+KfBGqIG3hLxzYp8RiIfG/HJyA6dhqpxG3y6yjO 0r24THuXceW7ygqQUB+J2KK8B1iWTwiMBvvIav9tOQTcYkU+EFtN7zwkC3aN2HV8I7QLDUWw OyWZ1+J1ff3xyCjMhZ0SaBV8kUy981RE8lnmy/T6lE9iFfj2roSkCLcUkODb9mz1BSeg7l1J yRGqQ2ypxS3l77h+JC1SMRrDUz1vFIIAuvQEjJgnV5JUjmNi/0s+/HQU8YRlQWERSH9pHwFL ZgSwH5hqCLFjiGLxxHqJ4JZLoP7J1I5tpuUkbVPhreRNNZ9ro0Wtd9cAEQEAAcLBZQQYAQgA DwUCWD2ryQIbDAUJCWYBgAAKCRBzOWT4unEhz2qgD/95NfvOedTfZ2P0hXTHlE0oGL9pIP21 dOng/fJT1yc4nA4MfNV3Hf72Gpw/XLpnMgovanqj+15ZyFPirCaB9lCjEiorzSsLN9k0I1OC +gIbouFHgYo3nzeRJf/hMlAzef7sqjuD5WyI7miMeaKXkjTGyjC39xX2nq5EHCI8V/uBtT94 3cyZmCrEl64AKjlnFfkNKhlYWpfDWSVSxz79QAIw0wW4ILNFfAp3z4DPjqGut98XBlmtQlDj RMlqeUHDIGLQjKNmxH95vbTS9eAFom6jA99Bl4nWCWUYHoGA/y7Ov6z9vQwqkJ4WqPMg+mas 7nZNQiexBj3tG5pRU2M7NURnaLiINFXid+kjKmNEUgNyd0haIqiIRtkRWZ2zvAwfudS7HDq1 RB6GWGHtJrVFRIkgs3gBoyPz3kSwlYieid6Ywquxd3dQqkN6cdlnvt2uossgRnqXx5HugP81 Faadir4t4t6HqoLHynzvvT9fMijT//O6Fb0MFqZP2rf3i7zh7/rwtpdxI2m/SbTJgvMqlvGn riBgDbjEz8XNMGqMk/WPNcKkk8prCPta9ltMl7yd3LqzCG6KRz7TtQae25BcBF1IKobZYbgf qc5fRxkCHCy6IDu70pve2tt1hzvZquE2Z5uTMFp2k213HJQKklY/jAOmVhM2O2T2oSaKAr1u MUmXcw== Organization: 2ndQuadrant France Message-ID: <88d31bc1-575f-db25-2a2e-53f8a52f99e2@2ndquadrant.com> Date: Thu, 9 Aug 2018 23:35:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180809190913.GB14011@momjian.us> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 09/08/18 21:09, Bruce Momjian wrote: > On Thu, Aug 9, 2018 at 01:11:05PM +0300, KES wrote: >> Bruce: >>> Yes, it would work, but doing that only for equality would be >>> surprising >> to many people >> >> Why surprising? It is >> [documented](https://www.postgresql.org/docs/current/static/sql-create >> table.html#sql-createtable-exclude): >>> If all of the specified operators test for equality, this is >>> equivalent to a UNIQUE constraint, although an ordinary unique >>> constraint will be faster. >> >> Thus the UNIQUE constraint is just particular case of exclusion >> constraint, is not? > > Well, for me a UNIQUE constraint guarantees each discrete value is > unique, while exclusion constraint says discrete or ranges or geometric > types don't overlap. I realize equality is a special case of discrete, > but having such cases be marked as UNIQUE seems too confusing. One of the things I'm currently trying to implement is the WITHOUT OVERLAPS for UNIQUE constraints. See SQL:2016 section 11.7 -- Vik Fearing +33 6 46 75 15 36 http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support