Wiki / Connection Parameters / Session and protocol
min_protocol_version
Specifies the minimum protocol version to allow for the connection. The default is to allow any version of the PostgreSQL protocol supported by libpq, which currently means 3.0 . If the server does not support at least this protocol version the conn…
Reading PostgreSQL 18.6.
Description
Specifies the minimum protocol version to allow for the connection. The default is to allow any version of the PostgreSQL protocol supported by libpq, which currently means 3.0 . If the server does not support at least this protocol version the connection will be closed.
- Client library
- libpq 18.6
- Manual definition
- Documented
- Source environment fallback
- PGMINPROTOCOLVERSION
- Compiled fallback expression
- NULL
Usage
min_protocol_versionDefault resolution and service-file precedence
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.
Environment variable evidence
PGMINPROTOCOLVERSION behaves the same as the min_protocol_version connection parameter.
Environment fallback
| Variable | Documented behavior |
|---|---|
| PGMINPROTOCOLVERSION | PGMINPROTOCOLVERSION behaves the same as the min_protocol_version connection parameter. |
Manual definition
min_protocol_version-
Specifies the minimum protocol version to allow for the connection. The default is to allow any version of the PostgreSQL protocol supported by libpq, which currently means
3.0. If the server does not support at least this protocol version the connection will be closed.The current supported values are
3.0,3.2, andlatest. Thelatestvalue is equivalent to the latest protocol version supported by the libpq version being used, which is currently3.2.
Related entries
Documentation and source
- 18.6 English manual · libpq-connect.html
- 18.6 libpq connection option declarations
- 18.6 English manual · libpq-envars.html
- 18.6 English manual · libpq-pgservice.html
Source build
- Version
- 18.6
- Build
- https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
- Source fingerprint
ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8
Compare versions
PostgreSQL 17 → 18: added.
--- PostgreSQL 17
+++ PostgreSQL 18
@@ -1 +1,10 @@
-Not recorded in this version
+{
+ "compiled_default_expression": "NULL",
+ "default_evidence": [
+ "Specifies the minimum protocol version to allow for the connection. The default is to allow any version of the PostgreSQL protocol supported by libpq, which currently means 3.0 . If the server does not support at least this protocol version the connection will be closed."
+ ],
+ "definition": "Specifies the minimum protocol version to allow for the connection. The default is to allow any version of the PostgreSQL protocol supported by libpq, which currently means 3.0 . If the server does not support at least this protocol version the connection will be closed. The current supported values are 3.0 , 3.2 , and latest . The latest value is equivalent to the latest protocol version supported by the libpq version being used, which is currently 3.2 .",
+ "documented": true,
+ "environment": "PGMINPROTOCOLVERSION",
+ "keyword": "min_protocol_version"
+}Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.
Related entries
Export JSON · Back to Connection Parameters · Recorded in PostgreSQL 18 through 20; the first sample is not necessarily its introduction.