‘command’ • CLEAN CONNECTION • Cleans connection pool • CREATE NODE / ALTER NODE Postgres Conference China 2016 中国用户大会 Noteworthy • SELECT pgxc_pool_reload() • pgxc_clean for 2PC Postgres Conference conf • Very similar to regular PostgreSQL • But there are extra parameters • max_pool_size • min_pool_size • pool_maintenance _timeout • remote_query_cost • network_byte_cost • sequence_range •

page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally for vacuuming a buffer found in the shared buffer cache. It represents the cost to lock the buffer pool, lookup the shared hash table and scan the content of the page. The default value is 1. vacuum_cost_page_miss for vacuuming a buffer that has to be read from disk. This represents the effort to lock the buffer pool, lookup the shared hash table, read the desired block in from the disk and scan its content. The default

transactions as READ ONLY when possible. • Control the number of active connections, using a connection pool if needed. This is always an important performance consideration, but it can be particularly important page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally in the pg_locks system view. Both advisory locks and regular locks are stored in a shared memory pool whose size is defined by the configuration variables max_locks_per_transaction and max_connections

transactions as READ ONLY when possible. • Control the number of active connections, using a connection pool if needed. This is always an important performance consideration, but it can be particularly important page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally in the pg_locks system view. Both advisory locks and regular locks are stored in a shared memory pool whose size is defined by the configuration variables max_locks_per_transaction and max_connections

transactions as READ ONLY when possible. • Control the number of active connections, using a connection pool if needed. This is always an important performance consideration, but it can be particularly important page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally in the pg_locks system view. Both advisory locks and regular locks are stored in a shared memory pool whose size is defined by the configuration variables max_locks_per_transaction and max_connections

transactions as READ ONLY when possible. • Control the number of active connections, using a connection pool if needed. This is always an important performance consideration, but it can be particularly important page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally in the pg_locks system view. Both advisory locks and regular locks are stored in a shared memory pool whose size is defined by the configuration variables max_locks_per_transaction and max_connections

page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally for vacuuming a buffer found in the shared buffer cache. It represents the cost to lock the buffer pool, lookup the shared hash table and scan the content of the page. The default value is 1. vacuum_cost_page_miss for vacuuming a buffer that has to be read from disk. This represents the effort to lock the buffer pool, lookup the shared hash table, read the desired block in from the disk and scan its content. The default

page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally session can be found in the pg_locks system view. Advisory locks are allocated out of a shared memory pool whose size is defined by the configuration vari- ables max_locks_per_transaction and max_connections for vacuuming a buffer found in the shared buffer cache. It represents the cost to lock the buffer pool, lookup the shared hash table and scan the content of the page. The default value is one. vacuum_cost_page_miss

page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally session can be found in the pg_locks system view. Advisory locks are allocated out of a shared memory pool whose size is defined by the configuration vari- ables max_locks_per_transaction and max_connections for vacuuming a buffer found in the shared buffer cache. It represents the cost to lock the buffer pool, lookup the shared hash table and scan the content of the page. The default value is one. vacuum_cost_page_miss

transactions as READ ONLY when possible. • Control the number of active connections, using a connection pool if needed. This is always an important performance consideration, but it can be particularly important page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are released immediately after a row is fetched or updated. Application developers normally in the pg_locks system view. Both advisory locks and regular locks are stored in a shared memory pool whose size is defined by the configuration variables max_locks_per_transaction and max_connections