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The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/14/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span></dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are <code class=\"literal\">TLSv1</code>, <code class=\"literal\">TLSv1.1</code>, <code class=\"literal\">TLSv1.2</code> and <code class=\"literal\">TLSv1.3</code>. The supported protocols depend on the version of <span class=\"productname\">OpenSSL</span> used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "source_option": {"keyword": "ssl_max_protocol_version", "declaration": "\"ssl_max_protocol_version\", \"PGSSLMAXPROTOCOLVERSION\", NULL, NULL, \"SSL-Maximum-Protocol-Version\", \"\", 8, offsetof(struct pg_conn, ssl_max_protocol_version)", "environment": "PGSSLMAXPROTOCOLVERSION", "source_notes": [], "compiled_default_expression": "NULL"}, "comparison_data": {"keyword": "ssl_max_protocol_version", "definition": "This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. 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The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/15/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span></dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. 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The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/16/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span> </dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. 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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": ["PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."]}], "signature": "ssl_max_protocol_version", "documented": true, "description": ["This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/17/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span> </dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are <code class=\"literal\">TLSv1</code>, <code class=\"literal\">TLSv1.1</code>, <code class=\"literal\">TLSv1.2</code> and <code class=\"literal\">TLSv1.3</code>. The supported protocols depend on the version of <span class=\"productname\">OpenSSL</span> used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "source_option": {"keyword": "ssl_max_protocol_version", "declaration": "\"ssl_max_protocol_version\", \"PGSSLMAXPROTOCOLVERSION\", NULL, NULL, \"SSL-Maximum-Protocol-Version\", \"\", 8, offsetof(struct pg_conn, ssl_max_protocol_version)", "environment": "PGSSLMAXPROTOCOLVERSION", "source_notes": [], "compiled_default_expression": "NULL"}, "comparison_data": {"keyword": "ssl_max_protocol_version", "definition": "This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. 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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. 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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."]}, {"title": "Environment variable evidence", "paragraphs": ["PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."]}], "signature": "ssl_max_protocol_version", "documented": true, "description": ["This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/19/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span> </dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are <code class=\"literal\">TLSv1</code>, <code class=\"literal\">TLSv1.1</code>, <code class=\"literal\">TLSv1.2</code> and <code class=\"literal\">TLSv1.3</code>. The supported protocols depend on the version of <span class=\"productname\">OpenSSL</span> used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "source_option": {"keyword": "ssl_max_protocol_version", "declaration": "\"ssl_max_protocol_version\", \"PGSSLMAXPROTOCOLVERSION\", NULL, NULL, \"SSL-Maximum-Protocol-Version\", \"\", 8, offsetof(struct pg_conn, ssl_max_protocol_version)", "environment": "PGSSLMAXPROTOCOLVERSION", "source_notes": [], "compiled_default_expression": "NULL"}, "comparison_data": {"keyword": "ssl_max_protocol_version", "definition": "This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.", "documented": true, "environment": "PGSSLMAXPROTOCOLVERSION", "default_evidence": [], "compiled_default_expression": "NULL"}, "comparison_hash": "1366aa789a93abdf16ef31f855fedd4e40f338e0c1d0aaee5bc8cc8efcb197aa", "default_evidence": [], "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. 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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": ["PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."]}], "signature": "ssl_max_protocol_version", "documented": true, "description": ["This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/devel/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span> </dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are <code class=\"literal\">TLSv1</code>, <code class=\"literal\">TLSv1.1</code>, <code class=\"literal\">TLSv1.2</code> and <code class=\"literal\">TLSv1.3</code>. The supported protocols depend on the version of <span class=\"productname\">OpenSSL</span> used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "source_option": {"keyword": "ssl_max_protocol_version", "declaration": "\"ssl_max_protocol_version\", \"PGSSLMAXPROTOCOLVERSION\", NULL, NULL, \"SSL-Maximum-Protocol-Version\", \"\", 8, offsetof(struct pg_conn, ssl_max_protocol_version)", "environment": "PGSSLMAXPROTOCOLVERSION", "source_notes": [], "compiled_default_expression": "NULL"}, "comparison_data": {"keyword": "ssl_max_protocol_version", "definition": "This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.", "documented": true, "environment": "PGSSLMAXPROTOCOLVERSION", "default_evidence": [], "compiled_default_expression": "NULL"}, "comparison_hash": "1366aa789a93abdf16ef31f855fedd4e40f338e0c1d0aaee5bc8cc8efcb197aa", "default_evidence": [], "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": "PGSSLMAXPROTOCOLVERSION"}, {"label": "Compiled fallback expression", "value": "NULL"}], "tables": [{"key": "environment", "rows": [{"name": {"url": "/docs/18/libpq-envars.html", "text": "PGSSLMAXPROTOCOLVERSION"}, "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "title": "Environment fallback", "columns": [{"key": "name", "label": "Variable"}, {"key": "description", "label": "Documented behavior"}]}], "keyword": "ssl_max_protocol_version", "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-SSL-MAX-PROTOCOL-VERSION", "file": "libpq-connect.html", "label": "18.6 English manual \u00b7 libpq-connect.html", "anchor": "LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "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": ["PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."]}], "signature": "ssl_max_protocol_version", "documented": true, "description": ["This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol."], "environment": [{"name": "PGSSLMAXPROTOCOLVERSION", "source_url": "/docs/18/libpq-envars.html", "description": "PGSSLMAXPROTOCOLVERSION behaves the same as the ssl_max_protocol_version connection parameter."}], "manual_html": "<div><dl class=\"variablelist\"><dt id=\"LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION\"><span class=\"term\"><code class=\"literal\">ssl_max_protocol_version</code></span> </dt><dd>\n<p>This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are <code class=\"literal\">TLSv1</code>, <code class=\"literal\">TLSv1.1</code>, <code class=\"literal\">TLSv1.2</code> and <code class=\"literal\">TLSv1.3</code>. The supported protocols depend on the version of <span class=\"productname\">OpenSSL</span> used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.</p>\n</dd></dl></div>", "manual_path": "libpq-connect.html#LIBPQ-CONNECT-SSL-MAX-PROTOCOL-VERSION", "source_option": {"keyword": "ssl_max_protocol_version", "declaration": "\"ssl_max_protocol_version\", \"PGSSLMAXPROTOCOLVERSION\", NULL, NULL, \"SSL-Maximum-Protocol-Version\", \"\", 8, offsetof(struct pg_conn, ssl_max_protocol_version)", "environment": "PGSSLMAXPROTOCOLVERSION", "source_notes": [], "compiled_default_expression": "NULL"}, "comparison_data": {"keyword": "ssl_max_protocol_version", "definition": "This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.", "documented": true, "environment": "PGSSLMAXPROTOCOLVERSION", "default_evidence": [], "compiled_default_expression": "NULL"}, "comparison_hash": "1366aa789a93abdf16ef31f855fedd4e40f338e0c1d0aaee5bc8cc8efcb197aa", "default_evidence": [], "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 +1,8 @@\n-Not recorded in this version\n+{\n+  \"compiled_default_expression\": \"NULL\",\n+  \"default_evidence\": [],\n+  \"definition\": \"This parameter specifies the maximum SSL/TLS protocol version to allow for the connection. Valid values are TLSv1 , TLSv1.1 , TLSv1.2 and TLSv1.3 . The supported protocols depend on the version of OpenSSL used, older versions not supporting the most modern protocol versions. If not set, this parameter is ignored and the connection will use the maximum bound defined by the backend, if set. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.\",\n+  \"documented\": true,\n+  \"environment\": \"PGSSLMAXPROTOCOLVERSION\",\n+  \"keyword\": \"ssl_max_protocol_version\"\n+}"}}