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Sat, 19 May 2018 16:27:33 -0700 (PDT) Subject: Re: Fix for FETCH FIRST syntax problems To: Tom Lane , Andrew Gierth Cc: pgsql-hackers@postgresql.org References: <877enz476l.fsf@news-spur.riddles.org.uk> <22981.1526770675@sss.pgh.pa.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: <03da97fc-9d6b-cbe1-c28f-cee7c1ba5c38@2ndquadrant.com> Date: Sun, 20 May 2018 01:27:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <22981.1526770675@sss.pgh.pa.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 20/05/18 00:57, Tom Lane wrote: > Andrew Gierth writes: >> Attached is a draft patch for fixing that, which additionally fixes the >> ugly wart that OFFSET ROW/ROWS and FETCH FIRST [] ROW/ROWS ONLY >> had very different productions for ; both now accept c_expr there. > > LGTM, except please s/presense/presence/ in grammar comment. > Also, why'd you back off "must write" to "should write" in the docs? > This doesn't make the parens any more optional than before. It certainly does. It allows this now: PREPARE foo AS TABLE bar FETCH FIRST $1 ROWS ONLY; >> I think a case can be made that this should be backpatched; thoughts? > > Meh, -0.5. This is not really a bug, because it's operating as designed. > You've found a reasonably painless way to improve the grammar, which is > great, but it seems more like a feature addition than a bug fix. > > I'd be fine with sneaking this into v11, though. I'm +1 for backpatching it. It may be operating as designed by PeterE ten years ago, but it's not operating as designed by the SQL standard. -- Vik Fearing +33 6 46 75 15 36 http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support