2016 中国用户大会 Postgres-X* Landscape • Postgres-XL based on Postgres-XC – Data node to data node communication for performance • Postgres-X2 based on PG 9.3, continuation of XC • Postgres-XC fork called Data Nodes • Actual data storage • Local execution of queries • Direct Data Node <-> Data Node communication and row shipping • Global Transaction Manager (GTM) • Provides a consistent view to transactions and put in shared queue for consumption for other datanodes for joining. Datanode-datanode communication and parallelism Postgres Conference China 2016 中国用户大会 PostgreSQL Differences Postgres Conference

TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a not present, client certificates will not be requested or checked. In this mode, SSL provides communication security but not authentication. The files server.key, server.crt, and root.crt are only examined of host to connect to. If this begins with a slash, it specifies Unix-domain communication rather than TCP/IP communication; the value is the name of the directory in which the socket 354 Chapter 27

TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a not present, client certificates will not be requested or checked. In this mode, SSL provides communication security but not authentication. The files server.key, server.crt, and root.crt are only examined processes to run groups of tests in parallel. Parallel testing gives confidence that interprocess communication and locking are working correctly. For historical reasons, the sequen- tial test is usually run

TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a not present, client certificates will not be requested or checked. In this mode, SSL provides communication security but not authentication. The files server.key, server.crt, root.crt, and root.crl are backup server, and that load balanced servers might return slightly stale results. Asynchronous communication is used when synchronous would be too slow. Solutions can also be categorized by their granularity

systems synchronously (without caching) to avoid this. (Storage Area Networks (SAN) use a low-level communication protocol rather than NFS.) 17.3. Starting the Database Server Before anyone can access the database TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a present, client certificates will not be requested or checked. In this mode, SSL provides encrypted communication but not authentication. The files server.key, server.crt, root.crt, and root.crl are only examined

systems synchronously (without caching) to avoid this. (Storage Area Networks (SAN) use a low-level communication protocol rather than NFS.) 17.3. Starting the Database Server Before anyone can access the database TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a present, client certificates will not be requested or checked. In this mode, SSL provides encrypted communication but not authentication. The files server.key, server.crt, root.crt, and root.crl are only examined

TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a not present, client certificates will not be requested or checked. In this mode, SSL provides communication security but not authentication. The files server.key, server.crt, and root.crt are only examined of host to connect to. If this begins with a slash, it specifies Unix-domain communication rather than TCP/IP communication; the value is the name of the directory in which the socket 390 Chapter 28

TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a not present, client certificates will not be requested or checked. In this mode, SSL provides communication security but not authentication. The files server.key, server.crt, and root.crt are only examined of host to connect to. If this begins with a slash, it specifies Unix-domain communication rather than TCP/IP communication; the value is the name of the directory in which the socket 388 Chapter 28

this. Also, soft-mounting NFS is not recommended. (Storage Area Networks (SAN) use a low-level communication protocol rather than NFS.) 17.3. Starting the Database Server Before anyone can access the database TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a 8 before using this. The default is off. This parameter can only be set at server start. SSL communication is only possible with TCP/IP connections. ssl_renegotiation_limit (integer) Specifies how much

this. Also, soft-mounting NFS is not recommended. (Storage Area Networks (SAN) use a low-level communication protocol rather than NFS.) 17.3. Starting the Database Server Before anyone can access the database TCP/IP communication is attempted. A common mistake is to forget to configure the server to allow TCP/IP connections. Alternatively, you’ll get this when attempting Unix-domain socket communication to a before using this. The default is off. This param- eter can only be set at server start. SSL communication is only possible with TCP/IP connections. ssl_renegotiation_limit (integer) Specifies how much