{"Entry":{"collection":"conn","key":"target-session-attrs","name":"target_session_attrs","aliases":["PGTARGETSESSIONATTRS","target_session_attrs"],"metadata":{"aliases":["PGTARGETSESSIONATTRS","target_session_attrs"],"category":"Connection destination","content_hash":"36300722f2e6d2ed355be886a54f817b625dcc468acbbf9b779010fbfec6828d","imported_at":"2026-09-30T00:40:35.195573+08:00","name":"target_session_attrs","name_zh":"","slug":"target-session-attrs","summary":"This option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:"}},"Definition":{"Collection":"conn","Key":"target-session-attrs","SourceDatabase":"center","Version":"18","SourceTable":"connection_parameter","SourceKey":"target-session-attrs","SourceRevision":"ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8","Facts":{"comparison_data":{"compiled_default_expression":"DefaultTargetSessionAttrs","default_evidence":["session must accept read-write transactions by default (that is, the server must not be in hot standby mode and the default_transaction_read_only parameter must be off )","session must not accept read-write transactions by default (the converse)"],"definition":"This option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes: any (default) any successful connection is acceptable read-write session must accept read-write transactions by default (that is, the server must not be in hot standby mode and the default_transaction_read_only parameter must be off ) read-only session must not accept read-write transactions by default (the converse) primary server must not be in hot standby mode standby server must be in hot standby mode prefer-standby first try to find a standby server, but if none of the listed hosts is a standby server, try again in any mode","documented":true,"environment":"PGTARGETSESSIONATTRS","keyword":"target_session_attrs"},"comparison_hash":"c66b8f5bf0ca0f898f8ff39c1588e0405c263592f5997098b467b8064bd9c45b","default_evidence":["session must accept read-write transactions by default (that is, the server must not be in hot standby mode and the default_transaction_read_only parameter must be off )","session must not accept read-write transactions by default (the converse)"],"description":["This option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:"],"documented":true,"environment":[{"description":"PGTARGETSESSIONATTRS behaves the same as the target_session_attrs connection parameter.","name":"PGTARGETSESSIONATTRS","source_url":"/docs/18/libpq-envars.html"}],"facts":[{"label":"Client library","value":"libpq 18.6"},{"label":"Manual definition","value":"Documented"},{"label":"Source environment fallback","value":"PGTARGETSESSIONATTRS"},{"label":"Compiled fallback expression","value":"DefaultTargetSessionAttrs"}],"keyword":"target_session_attrs","manual_html":"\u003cdiv\u003e\u003cdl class=\"variablelist\"\u003e\u003cdt id=\"LIBPQ-CONNECT-TARGET-SESSION-ATTRS\"\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003etarget_session_attrs\u003c/code\u003e\u003c/span\u003e \u003c/dt\u003e\u003cdd\u003e\n\u003cp\u003eThis option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:\u003c/p\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eany\u003c/code\u003e (default)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eany successful connection is acceptable\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eread-write\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must accept read-write transactions by default (that is, the server must not be in hot standby mode and the \u003ccode class=\"varname\"\u003edefault_transaction_read_only\u003c/code\u003e parameter must be \u003ccode class=\"literal\"\u003eoff\u003c/code\u003e)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eread-only\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must not accept read-write transactions by default (the converse)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eprimary\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must not be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003estandby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eprefer-standby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003efirst try to find a standby server, but if none of the listed hosts is a standby server, try again in \u003ccode class=\"literal\"\u003eany\u003c/code\u003e mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e\u003c/div\u003e","manual_path":"libpq-connect.html#LIBPQ-CONNECT-TARGET-SESSION-ATTRS","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."],"related":[{"label":"Connection service file","url":"/docs/18/libpq-pgservice.html"},{"label":"Password file","url":"/docs/18/libpq-pgpass.html"},{"label":"All libpq environment variables","url":"/docs/18/libpq-envars.html"}],"release":{"channel":"stable","evidence_kind":"English manual and source declarations","label":"18.6","major":"18","manifest":{"index":"index.html","major":"18","pages":1148,"pdf":{"A4":{"built_at":"2026-09-26","bytes":15865106,"pages":3154,"sha256":"19512c405da53f9f7fcf0abba359223aa65f021be025bf3411381918f92e3190","url":"/files/documentation/pdf/18/postgresql-18-A4.pdf"},"US":{"built_at":"2026-09-26","bytes":15748059,"pages":3328,"sha256":"facbe6c229e598b872d3d98bef53308f46e06746006fa4590de9a7de9dd46319","url":"/files/documentation/pdf/18/postgresql-18-US.pdf"}},"release":"18.6","source_mode":"en SGML built with pinned official archive","source_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","source_url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","svg_assets":3,"tree":"18"},"ref":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","revision":"ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8","source_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"},"sections":[{"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":"Default resolution and service-file precedence"},{"paragraphs":["PGTARGETSESSIONATTRS behaves the same as the target_session_attrs connection parameter."],"title":"Environment variable evidence"}],"signature":"target_session_attrs","source_option":{"compiled_default_expression":"DefaultTargetSessionAttrs","declaration":"\"target_session_attrs\", \"PGTARGETSESSIONATTRS\", DefaultTargetSessionAttrs, NULL, \"Target-Session-Attrs\", \"\", 15, offsetof(struct pg_conn, target_session_attrs)","environment":"PGTARGETSESSIONATTRS","keyword":"target_session_attrs","source_notes":[]},"sources":[{"anchor":"LIBPQ-CONNECT-TARGET-SESSION-ATTRS","file":"libpq-connect.html","label":"18.6 English manual · libpq-connect.html","sha256":"c26a7fc3dcda6066cfe540641ae2690faf3d3c03277f30b4dfc2328ab45c212f","url":"/docs/18/libpq-connect.html#LIBPQ-CONNECT-TARGET-SESSION-ATTRS"},{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","file":"src/interfaces/libpq/fe-connect.c","label":"18.6 libpq connection option declarations","sha256":"44a6e386cbfd67ebe768d6ef5493098119c2e6b4796239d53e5ed7b122b206a5","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"},{"anchor":"","file":"libpq-envars.html","label":"18.6 English manual · libpq-envars.html","sha256":"d64db73f3d48127bb984a5f775e77b7bcca2ba4bd218333cf24a45fcdd7c4363","url":"/docs/18/libpq-envars.html"},{"anchor":"","file":"libpq-pgservice.html","label":"18.6 English manual · libpq-pgservice.html","sha256":"6035a3f0ee1d0fd80db5bf58834390b884eecd23206659bdf6f07560deea5aa7","url":"/docs/18/libpq-pgservice.html"}],"tables":[{"columns":[{"key":"name","label":"Variable"},{"key":"description","label":"Documented behavior"}],"key":"environment","rows":[{"description":"PGTARGETSESSIONATTRS behaves the same as the target_session_attrs connection parameter.","name":{"text":"PGTARGETSESSIONATTRS","url":"/docs/18/libpq-envars.html"}}],"title":"Environment fallback"}]},"ManualEvidence":{"manual_path":"libpq-connect.html#LIBPQ-CONNECT-TARGET-SESSION-ATTRS","release":{"channel":"stable","evidence_kind":"English manual and source declarations","label":"18.6","major":"18","manifest":{"index":"index.html","major":"18","pages":1148,"pdf":{"A4":{"built_at":"2026-09-26","bytes":15865106,"pages":3154,"sha256":"19512c405da53f9f7fcf0abba359223aa65f021be025bf3411381918f92e3190","url":"/files/documentation/pdf/18/postgresql-18-A4.pdf"},"US":{"built_at":"2026-09-26","bytes":15748059,"pages":3328,"sha256":"facbe6c229e598b872d3d98bef53308f46e06746006fa4590de9a7de9dd46319","url":"/files/documentation/pdf/18/postgresql-18-US.pdf"}},"release":"18.6","source_mode":"en SGML built with pinned official archive","source_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","source_url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","svg_assets":3,"tree":"18"},"ref":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","revision":"ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8","source_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"},"sources":[{"anchor":"LIBPQ-CONNECT-TARGET-SESSION-ATTRS","file":"libpq-connect.html","label":"18.6 English manual · libpq-connect.html","sha256":"c26a7fc3dcda6066cfe540641ae2690faf3d3c03277f30b4dfc2328ab45c212f","url":"/docs/18/libpq-connect.html#LIBPQ-CONNECT-TARGET-SESSION-ATTRS"},{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","file":"src/interfaces/libpq/fe-connect.c","label":"18.6 libpq connection option declarations","sha256":"44a6e386cbfd67ebe768d6ef5493098119c2e6b4796239d53e5ed7b122b206a5","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"},{"anchor":"","file":"libpq-envars.html","label":"18.6 English manual · libpq-envars.html","sha256":"d64db73f3d48127bb984a5f775e77b7bcca2ba4bd218333cf24a45fcdd7c4363","url":"/docs/18/libpq-envars.html"},{"anchor":"","file":"libpq-pgservice.html","label":"18.6 English manual · libpq-pgservice.html","sha256":"6035a3f0ee1d0fd80db5bf58834390b884eecd23206659bdf6f07560deea5aa7","url":"/docs/18/libpq-pgservice.html"}]},"MeasuredEvidence":{}},"Text":{"Collection":"conn","Key":"target-session-attrs","SourceDatabase":"center","Version":"18","Locale":"en","Title":"target_session_attrs","Summary":"This option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:","BodyHTML":"\u003cdiv\u003e\u003cdl\u003e\u003cdt id=\"LIBPQ-CONNECT-TARGET-SESSION-ATTRS\"\u003e\u003cspan\u003e\u003ccode\u003etarget_session_attrs\u003c/code\u003e\u003c/span\u003e \u003c/dt\u003e\u003cdd\u003e\n\u003cp\u003eThis option determines whether the session must have certain properties to be acceptable. It\u0026#39;s typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:\u003c/p\u003e\n\u003cdiv\u003e\n\u003cdl\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003eany\u003c/code\u003e (default)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eany successful connection is acceptable\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003eread-write\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must accept read-write transactions by default (that is, the server must not be in hot standby mode and the \u003ccode\u003edefault_transaction_read_only\u003c/code\u003e parameter must be \u003ccode\u003eoff\u003c/code\u003e)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003eread-only\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must not accept read-write transactions by default (the converse)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003eprimary\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must not be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003estandby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003e\u003ccode\u003eprefer-standby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003efirst try to find a standby server, but if none of the listed hosts is a standby server, try again in \u003ccode\u003eany\u003c/code\u003e mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e\u003c/div\u003e","SourceRevision":"ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8","ContentHash":"14f25d1e3d332c903070f43f33a515ca56319d769552e4ca4f774920fe4b9ac2","Payload":{"description":["This option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:"],"manual_html":"\u003cdiv\u003e\u003cdl class=\"variablelist\"\u003e\u003cdt id=\"LIBPQ-CONNECT-TARGET-SESSION-ATTRS\"\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003etarget_session_attrs\u003c/code\u003e\u003c/span\u003e \u003c/dt\u003e\u003cdd\u003e\n\u003cp\u003eThis option determines whether the session must have certain properties to be acceptable. It's typically used in combination with multiple host names to select the first acceptable alternative among several hosts. There are six modes:\u003c/p\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eany\u003c/code\u003e (default)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eany successful connection is acceptable\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eread-write\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must accept read-write transactions by default (that is, the server must not be in hot standby mode and the \u003ccode class=\"varname\"\u003edefault_transaction_read_only\u003c/code\u003e parameter must be \u003ccode class=\"literal\"\u003eoff\u003c/code\u003e)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eread-only\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003esession must not accept read-write transactions by default (the converse)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eprimary\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must not be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003estandby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eserver must be in hot standby mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003e\u003ccode class=\"literal\"\u003eprefer-standby\u003c/code\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003efirst try to find a standby server, but if none of the listed hosts is a standby server, try again in \u003ccode class=\"literal\"\u003eany\u003c/code\u003e mode\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e\u003c/div\u003e","related":[{"label":"Connection service file","url":"/docs/18/libpq-pgservice.html"},{"label":"Password file","url":"/docs/18/libpq-pgpass.html"},{"label":"All libpq environment variables","url":"/docs/18/libpq-envars.html"}],"sections":[{"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":"Default resolution and service-file precedence"},{"paragraphs":["PGTARGETSESSIONATTRS behaves the same as the target_session_attrs connection parameter."],"title":"Environment variable evidence"}],"tables":[{"columns":[{"key":"name","label":"Variable"},{"key":"description","label":"Documented behavior"}],"key":"environment","rows":[{"description":"PGTARGETSESSIONATTRS behaves the same as the target_session_attrs connection parameter.","name":{"text":"PGTARGETSESSIONATTRS","url":"/docs/18/libpq-envars.html"}}],"title":"Environment fallback"}]}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20"],"Locales":["en"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}