-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 03/11/2014 12:26 PM, Simon Riggs wrote: > On 11 March 2014 03:41, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Joe Conway <m...@joeconway.com> writes: >>> I am probably missing something obvious, but why does the >>> AccessShareLock remain held on a table after a SELECT statement >>> is complete when in a transaction block? >> >> *Any* lock acquired by user command is held till end of >> transaction; AccessShareLock isn't special. >> >> In general, releasing early would increase the risk of >> undesirable behaviors such as tables changing definition >> mid-transaction. > > I thought "good question" at first, but the workaround is > simple... just don't use multi-step transactions, submit each > request as a separate transaction.
Yeah, I told them that already. Unfortunately in this environment it is not an option. It isn't a huge problem, but I did find it surprising (as did the client) that a purely read-only transaction could cause a deadlock with a concurrent CREATE TABLE. It would seem that once the SELECT statement has finished we could drop the AccessShareLock, but I guess that would open a can of works that we don't want to contemplate. Joe - -- Joe Conway credativ LLC: http://www.credativ.us Linux, PostgreSQL, and general Open Source Training, Service, Consulting, & 24x7 Support -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTH0tlAAoJEDfy90M199hlxtUP/isxPT8ZRPf8X/vM3+vS4XR2 CTwNB292c9TLADSfi4lHFCXu8kqOpx29/9PJHUHrhTrCQE10USdC5uBN04u9si0a SL5cmwtSeSn3YacgksNpPz0u9spGVdO4XqcMq9oh5gcsSeRf14NXIPAvUk7yRPTA leVo7CArOfyld0QdRNw3JP50tAoHYJQynomkClg/9U+jYtk/aBpCSe/KL++d5esl xt8iGZQ/wdZu+vWSdeaJMvGUYNOu4ts7wgtrqvLv9qLXDAiftfIC6NuakKY3WHY6 2OYz64Xd+wH0ZWEhYnSjkQR354RXSm0JQNos02nAjviDON6r6OJk3ny7Rw/mKbAw ZR2Ze3EFYcnMeV9Rrg1DccDzqWK9lq7tHD++IfbQ/36xvOcxh4pQuZQt9erTJ4q1 l9MrHE8PA4mVDgcGlhcdzDl+/po/0ghy/HWgH72NjGpEX+fChh7Pad9ZCO5r33Du V3EZXfdLwnokx/VRi0N61ZeBJCCKWSST3SrZKJk5ao7y8dQPIICryLJlM9sTxlXf 2wiQlybElpaqWxy+Ou3M7EYdPvGNOLHMCt8yUK5n+RFTEtljKNwy1E9NvJWWiVl9 SfA/6GXXsGlO0rQ723R1vPAFHtTo82ibQaiCNujVPu/2yecKl4MsdtaZApkilLqx EPoWWGrs3cURvar6gmju =DOcV -----END PGP SIGNATURE----- -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
