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It is only supported over SSL connections with <span class=\"productname\">PostgreSQL</span> 11 or later servers using the <code class=\"literal\">SCRAM</code> authentication method.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING", "source_option": {"keyword": "channel_binding", "declaration": "\"channel_binding\", \"PGCHANNELBINDING\", DefaultChannelBinding, NULL, \"Channel-Binding\", \"\", 8, offsetof(struct pg_conn, channel_binding)", "environment": "PGCHANNELBINDING", "source_notes": [], "compiled_default_expression": "DefaultChannelBinding"}, "comparison_data": {"keyword": "channel_binding", "definition": "This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable . Channel binding is a method for the server to authenticate itself to the client. It is only supported over SSL connections with PostgreSQL 11 or later servers using the SCRAM authentication method.", "documented": true, "environment": "PGCHANNELBINDING", "default_evidence": ["This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable ."], "compiled_default_expression": "DefaultChannelBinding"}, "comparison_hash": "939fb3f63941cfa9d9db8de426fff2b87d218db1f8e1249111d6d71d981b23e4", "default_evidence": ["This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable ."], "precedence_evidence": ["The following environment variables can be used to select default connection parameter values, which will be used by PQconnectdb , PQsetdbLogin and PQsetdb if no value is directly specified by the calling code. These are useful to avoid hard-coding database connection information into simple client applications, for example.", "Service names can be defined in either a per-user service file or a system-wide file. If the same service name exists in both the user and the system file, the user file takes precedence. By default, the per-user service file is named ~/.pg_service.conf . On Microsoft Windows, it is named %APPDATA%\\postgresql\\.pg_service.conf (where %APPDATA% refers to the Application Data subdirectory in the user's profile). A different file name can be specified using the servicefile key word in a libpq connection string or by setting the environment variable PGSERVICEFILE . The system-wide file is named pg_service.conf . By default it is sought in the etc directory of the PostgreSQL installation (use pg_config --sysconfdir to identify this directory precisely). Another directory, but not a different file name, can be specified by setting the environment variable PGSYSCONFDIR .", "Connection parameters obtained from a service file are combined with parameters obtained from other sources. A service file setting overrides the corresponding environment variable, and in turn can be overridden by a value given directly in the connection string. For example, using the above service file, a connection string service=mydb port=5434 will use host somehost , port 5434 , user admin , and other parameters as set by environment variables or built-in defaults."]}}}, "snapshot": {"facts": [{"label": "Client library", "value": "libpq 18.6"}, {"label": "Manual definition", "value": "Documented"}, {"label": "Source environment fallback", "value": "PGCHANNELBINDING"}, {"label": "Compiled fallback expression", "value": "DefaultChannelBinding"}], "tables": [{"key": "environment", "rows": [{"name": {"url": "/docs/18/libpq-envars.html", "text": "PGCHANNELBINDING"}, "description": "PGCHANNELBINDING behaves the same as the channel_binding connection parameter."}], "title": "Environment fallback", "columns": [{"key": "name", "label": "Variable"}, {"key": "description", "label": "Documented behavior"}]}], "keyword": "channel_binding", "related": [{"url": "/docs/18/libpq-pgservice.html", "label": "Connection service file"}, {"url": "/docs/18/libpq-pgpass.html", "label": "Password file"}, {"url": "/docs/18/libpq-envars.html", "label": "All libpq environment variables"}], "release": {"ref": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "label": "18.6", "major": "18", "channel": "stable", "manifest": {"pdf": {"A4": {"url": "/files/documentation/pdf/18/postgresql-18-A4.pdf", "bytes": 15865106, "pages": 3154, "sha256": "19512c405da53f9f7fcf0abba359223aa65f021be025bf3411381918f92e3190", "built_at": "2026-09-26"}, "US": {"url": "/files/documentation/pdf/18/postgresql-18-US.pdf", "bytes": 15748059, "pages": 3328, "sha256": "facbe6c229e598b872d3d98bef53308f46e06746006fa4590de9a7de9dd46319", "built_at": "2026-09-26"}}, "tree": "18", "index": "index.html", "major": "18", "pages": 1148, "release": "18.6", "source_url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "svg_assets": 3, "source_mode": "en SGML built with pinned official archive", "source_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "revision": "ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8", "evidence_kind": "English manual and source declarations", "source_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "sources": [{"url": "/docs/18/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING", "file": "libpq-connect.html", "label": "18.6 English manual \u00b7 libpq-connect.html", "anchor": "LIBPQ-CONNECT-CHANNEL-BINDING", "sha256": "c26a7fc3dcda6066cfe540641ae2690faf3d3c03277f30b4dfc2328ab45c212f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "file": "src/interfaces/libpq/fe-connect.c", "label": "18.6 libpq connection option declarations", "sha256": "44a6e386cbfd67ebe768d6ef5493098119c2e6b4796239d53e5ed7b122b206a5", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "/docs/18/libpq-envars.html", "file": "libpq-envars.html", "label": "18.6 English manual \u00b7 libpq-envars.html", "anchor": "", "sha256": "d64db73f3d48127bb984a5f775e77b7bcca2ba4bd218333cf24a45fcdd7c4363"}, {"url": "/docs/18/libpq-pgservice.html", "file": "libpq-pgservice.html", "label": "18.6 English manual \u00b7 libpq-pgservice.html", "anchor": "", "sha256": "6035a3f0ee1d0fd80db5bf58834390b884eecd23206659bdf6f07560deea5aa7"}], "sections": [{"title": "Default resolution and service-file precedence", "paragraphs": ["The following environment variables can be used to select default connection parameter values, which will be used by PQconnectdb , PQsetdbLogin and PQsetdb if no value is directly specified by the calling code. These are useful to avoid hard-coding database connection information into simple client applications, for example.", "Service names can be defined in either a per-user service file or a system-wide file. If the same service name exists in both the user and the system file, the user file takes precedence. By default, the per-user service file is named ~/.pg_service.conf . On Microsoft Windows, it is named %APPDATA%\\postgresql\\.pg_service.conf (where %APPDATA% refers to the Application Data subdirectory in the user's profile). A different file name can be specified by setting the environment variable PGSERVICEFILE . The system-wide file is named pg_service.conf . By default it is sought in the etc directory of the PostgreSQL installation (use pg_config --sysconfdir to identify this directory precisely). Another directory, but not a different file name, can be specified by setting the environment variable PGSYSCONFDIR .", "Connection parameters obtained from a service file are combined with parameters obtained from other sources. A service file setting overrides the corresponding environment variable, and in turn can be overridden by a value given directly in the connection string. For example, using the above service file, a connection string service=mydb port=5434 will use host somehost , port 5434 , user admin , and other parameters as set by environment variables or built-in defaults."]}, {"title": "Environment variable evidence", "paragraphs": ["PGCHANNELBINDING behaves the same as the channel_binding connection parameter."]}], "signature": "channel_binding", "documented": true, "description": ["This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable ."], "environment": [{"name": "PGCHANNELBINDING", "source_url": "/docs/18/libpq-envars.html", "description": "PGCHANNELBINDING behaves the same as the channel_binding connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-CHANNEL-BINDING\"><span class=\"term\"><code class=\"literal\">channel_binding</code></span> </dt><dd>\n<p>This option controls the client's use of channel binding. A setting of <code class=\"literal\">require</code> means that the connection must employ channel binding, <code class=\"literal\">prefer</code> means that the client will choose channel binding if available, and <code class=\"literal\">disable</code> prevents the use of channel binding. The default is <code class=\"literal\">prefer</code> if <span class=\"productname\">PostgreSQL</span> is compiled with SSL support; otherwise the default is <code class=\"literal\">disable</code>.</p>\n<p>Channel binding is a method for the server to authenticate itself to the client. It is only supported over SSL connections with <span class=\"productname\">PostgreSQL</span> 11 or later servers using the <code class=\"literal\">SCRAM</code> authentication method.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING", "source_option": {"keyword": "channel_binding", "declaration": "\"channel_binding\", \"PGCHANNELBINDING\", DefaultChannelBinding, NULL, \"Channel-Binding\", \"\", 8, offsetof(struct pg_conn, channel_binding)", "environment": "PGCHANNELBINDING", "source_notes": [], "compiled_default_expression": "DefaultChannelBinding"}, "comparison_data": {"keyword": "channel_binding", "definition": "This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable . Channel binding is a method for the server to authenticate itself to the client. It is only supported over SSL connections with PostgreSQL 11 or later servers using the SCRAM authentication method.", "documented": true, "environment": "PGCHANNELBINDING", "default_evidence": ["This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable ."], "compiled_default_expression": "DefaultChannelBinding"}, "comparison_hash": "939fb3f63941cfa9d9db8de426fff2b87d218db1f8e1249111d6d71d981b23e4", "default_evidence": ["This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable ."], "precedence_evidence": ["The following environment variables can be used to select default connection parameter values, which will be used by PQconnectdb , PQsetdbLogin and PQsetdb if no value is directly specified by the calling code. These are useful to avoid hard-coding database connection information into simple client applications, for example.", "Service names can be defined in either a per-user service file or a system-wide file. If the same service name exists in both the user and the system file, the user file takes precedence. By default, the per-user service file is named ~/.pg_service.conf . On Microsoft Windows, it is named %APPDATA%\\postgresql\\.pg_service.conf (where %APPDATA% refers to the Application Data subdirectory in the user's profile). A different file name can be specified by setting the environment variable PGSERVICEFILE . The system-wide file is named pg_service.conf . By default it is sought in the etc directory of the PostgreSQL installation (use pg_config --sysconfdir to identify this directory precisely). Another directory, but not a different file name, can be specified by setting the environment variable PGSYSCONFDIR .", "Connection parameters obtained from a service file are combined with parameters obtained from other sources. A service file setting overrides the corresponding environment variable, and in turn can be overridden by a value given directly in the connection string. For example, using the above service file, a connection string service=mydb port=5434 will use host somehost , port 5434 , user admin , and other parameters as set by environment variables or built-in defaults."]}, "comparison": {"left": "12", "right": "13", "status": "added", "diff": "--- PostgreSQL 12\n+++ PostgreSQL 13\n@@ -1 +1,10 @@\n-Not recorded in this version\n+{\n+  \"compiled_default_expression\": \"DefaultChannelBinding\",\n+  \"default_evidence\": [\n+    \"This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable .\"\n+  ],\n+  \"definition\": \"This option controls the client's use of channel binding. A setting of require means that the connection must employ channel binding, prefer means that the client will choose channel binding if available, and disable prevents the use of channel binding. The default is prefer if PostgreSQL is compiled with SSL support; otherwise the default is disable . Channel binding is a method for the server to authenticate itself to the client. It is only supported over SSL connections with PostgreSQL 11 or later servers using the SCRAM authentication method.\",\n+  \"documented\": true,\n+  \"environment\": \"PGCHANNELBINDING\",\n+  \"keyword\": \"channel_binding\"\n+}"}}