Mon Jun 13 13:10:29 PDT 2005
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On 6/10/2005 7:52 PM, Adam Haberlach wrote: > > I saw this behavior as well, and from the process listing it appeared that > slony uses a COPY command to do the initial transfer. I believe that > generally creates a lock, or otherwise should. The copy itself doesn't take that lock. What happens is that slony manipulates the system catalog to disable all user triggers on the table, delete all eventually existing data in the table, then use copy to fill in the initial content at subscribe set time. The first part requires an exclusive lock, and all actions for the whole subscribe set are done within one transaction (all tables together). Because of the "one transaction covers the whole subscibe set" detail, using select count(*) can't work anyway. Jan > > Once the copy is completed, then the system will start playing the > transactions that have logged during the interim. > > > -----Original Message----- > From: slony1-general-bounces at gborg.postgresql.org > [mailto:slony1-general-bounces at gborg.postgresql.org] On Behalf Of Marc Munro > Sent: Friday, June 10, 2005 3:26 PM > To: slony1-general at gborg.postgresql.org > Subject: [Slony1-general] Select being blocked during sync to slave. > > I am using slony and am synchronising a slave for the first time. In the > hope of seeing some progress on the slave I attempt to perform a select > count(*) on one of the tables. > > The select is blocked by an AccessExclusiveLock. I am wondering what slony > is doing at this point and why it needs to take out such a serious lock. > > Any and all explanations will be welcomed. > > > ps shows this: > > postgres 5987 0.0 0.4 19180 4188 ? S 15:16 0:00 postgres: > postgres testdb 192.168.1.111(33598) SELECT waiting > > A query of blocking locks shows this: > > object | trans | pid | mode | blocker > ---------------------------+-------+------+---------------------+------- > ---------------------------+-------+------+---------------------+-- > testdb.campaign_cost_pk | | 5754 | AccessShareLock | > testdb.csn_log_pk | | 5754 | RowExclusiveLock | > testdb.pg_trigger | | 5754 | AccessShareLock | > testdb.pg_trigger | | 5754 | RowExclusiveLock | > testdb.sl_subscribe | | 5754 | AccessShareLock | > testdb.csn_log_idx2 | | 5754 | RowExclusiveLock | > testdb.campaign | | 5754 | AccessShareLock | > testdb.campaign | | 5754 | RowExclusiveLock | > testdb.campaign | | 5754 | AccessExclusiveLock | > testdb.pg_rewrite | | 5754 | AccessShareLock | > testdb.pg_rewrite | | 5754 | RowExclusiveLock | > testdb.computer_sn_log | | 5754 | AccessShareLock | > testdb.computer_sn_log | | 5754 | RowExclusiveLock | > testdb.computer_sn_log | | 5754 | AccessExclusiveLock | > testdb.address_type_pk | | 5754 | AccessShareLock | > testdb.campaign_pk | | 5754 | AccessShareLock | > testdb.sl_log_1 | | 5754 | AccessShareLock | > testdb.sl_log_1 | | 5754 | RowExclusiveLock | > testdb.csn_cookie_idx1 | | 5754 | AccessShareLock | > testdb.pg_index | | 5754 | AccessShareLock | > testdb.pg_index | | 5754 | RowShareLock | > testdb.csn_log_idx3 | | 5754 | RowExclusiveLock | > testdb.csn_cookie_pk | | 5754 | AccessShareLock | > testdb.sl_log_2 | | 5754 | AccessShareLock | > testdb.sl_log_2 | | 5754 | RowExclusiveLock | > testdb.sl_set | | 5754 | AccessShareLock | > testdb.sl_set | | 5754 | RowShareLock | > testdb.campaign_cost | | 5754 | AccessShareLock | > testdb.campaign_cost | | 5754 | RowExclusiveLock | > testdb.campaign_cost | | 5754 | AccessExclusiveLock | > testdb.sl_table | | 5754 | AccessShareLock | > testdb.sl_table | | 5754 | RowShareLock | > testdb.sl_table | | 5754 | RowExclusiveLock | > | 9182 | 5754 | ExclusiveLock | > testdb.computer_sn_cookie | | 5754 | AccessShareLock | > testdb.computer_sn_cookie | | 5754 | RowExclusiveLock | > testdb.computer_sn_cookie | | 5754 | AccessExclusiveLock | > testdb.pg_attribute | | 5754 | AccessShareLock | > testdb.sl_config_lock | | 5754 | AccessExclusiveLock | > testdb.sl_trigger | | 5754 | AccessShareLock | > testdb.csn_pk | | 5754 | AccessShareLock | > testdb.pg_class | | 5754 | AccessShareLock | > testdb.pg_class | | 5754 | RowShareLock | > testdb.pg_class | | 5754 | RowExclusiveLock | > testdb.address_type | | 5754 | AccessShareLock | > testdb.address_type | | 5754 | RowExclusiveLock | > testdb.address_type | | 5754 | AccessExclusiveLock | > testdb.pg_namespace | | 5754 | AccessShareLock | > testdb.pg_namespace | | 5754 | RowShareLock | > testdb.csn_log_idx1 | | 5754 | RowExclusiveLock | > testdb.computer_sn | | 5754 | AccessShareLock | > testdb.computer_sn | | 5754 | RowExclusiveLock | > testdb.computer_sn | | 5754 | AccessExclusiveLock | > testdb.address_type | | 5987 | AccessShareLock | 5754 > | 9422 | 5987 | ExclusiveLock | 5754 > (55 rows) > > All responses will be welcomed. > > __ > Marc > > > _______________________________________________ > Slony1-general mailing list > Slony1-general at gborg.postgresql.org > http://gborg.postgresql.org/mailman/listinfo/slony1-general -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck at Yahoo.com #
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