docs: add version notes

docs/sources/administration/provisioning.md

@@ -168,9 +168,9 @@ Since not all datasources have the same configuration settings we only have the
 | sslmode | string | PostgreSQL | SSLmode. 'disable', 'require', 'verify-ca' or 'verify-full' |
 | postgresVersion | number | PostgreSQL | Postgres version as a number (903/904/905/906/1000) meaning v9.3, v9.4, ..., v10 |
 | timescaledb | boolean | PostgreSQL | Enable usage of TimescaleDB extension |
-| maxOpenConns | number | MySQL, PostgreSQL & MSSQL | Maximum number of open connections to the database |
-| maxIdleConns | number | MySQL, PostgreSQL & MSSQL | Maximum number of connections in the idle connection pool |
-| connMaxLifetime | number | MySQL, PostgreSQL & MSSQL | Maximum amount of time in seconds a connection may be reused |
+| maxOpenConns | number | MySQL, PostgreSQL & MSSQL | Maximum number of open connections to the database (Grafana v5.4+) |
+| maxIdleConns | number | MySQL, PostgreSQL & MSSQL | Maximum number of connections in the idle connection pool (Grafana v5.4+) |
+| connMaxLifetime | number | MySQL, PostgreSQL & MSSQL | Maximum amount of time in seconds a connection may be reused (Grafana v5.4+) |
 
 #### Secure Json Data
 

docs/sources/features/datasources/mssql.md

@@ -32,9 +32,9 @@ Name | Description
 *Database* | Name of your MSSQL database.
 *User* | Database user's login/username
 *Password* | Database user's password
-*Max open* | The maximum number of open connections to the database, default `unlimited`.
-*Max idle* | The maximum number of connections in the idle connection pool, default `2`.
-*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400` (4 hours).
+*Max open* | The maximum number of open connections to the database, default `unlimited` (Grafana v5.4+).
+*Max idle* | The maximum number of connections in the idle connection pool, default `2` (Grafana v5.4+).
+*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400`/4 hours (Grafana v5.4+).
 
 ### Min time interval
 
@@ -589,9 +589,9 @@ datasources:
     database: grafana
     user: grafana
     jsonData:
-      maxOpenConns: 0
-      maxIdleConns: 2
-      connMaxLifetime: 14400
+      maxOpenConns: 0         # Grafana v5.4+
+      maxIdleConns: 2         # Grafana v5.4+
+      connMaxLifetime: 14400  # Grafana v5.4+
     secureJsonData:
       password: "Password!"
 

docs/sources/features/datasources/mysql.md

@@ -35,9 +35,9 @@ Name | Description
 *Database* | Name of your MySQL database.
 *User* | Database user's login/username
 *Password* | Database user's password
-*Max open* | The maximum number of open connections to the database, default `unlimited`.
-*Max idle* | The maximum number of connections in the idle connection pool, default `2`.
-*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400` (4 hours).
+*Max open* | The maximum number of open connections to the database, default `unlimited` (Grafana v5.4+).
+*Max idle* | The maximum number of connections in the idle connection pool, default `2` (Grafana v5.4+).
+*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400`/4 hours. This should always be lower than configured [wait_timeout](https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_wait_timeout) in MySQL (Grafana v5.4+).
 
 ### Min time interval
 
@@ -320,7 +320,7 @@ datasources:
     user: grafana
     password: password
     jsonData:
-      maxOpenConns: 0
-      maxIdleConns: 2
-      connMaxLifetime: 14400
+      maxOpenConns: 0         # Grafana v5.4+
+      maxIdleConns: 2         # Grafana v5.4+
+      connMaxLifetime: 14400  # Grafana v5.4+
 ```

docs/sources/features/datasources/postgres.md

@@ -31,9 +31,9 @@ Name | Description
 *User* | Database user's login/username
 *Password* | Database user's password
 *SSL Mode* | This option determines whether or with what priority a secure SSL TCP/IP connection will be negotiated with the server.
-*Max open* | The maximum number of open connections to the database, default `unlimited`.
-*Max idle* | The maximum number of connections in the idle connection pool, default `2`.
-*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400` (4 hours).
+*Max open* | The maximum number of open connections to the database, default `unlimited` (Grafana v5.4+).
+*Max idle* | The maximum number of connections in the idle connection pool, default `2` (Grafana v5.4+).
+*Max lifetime* | The maximum amount of time in seconds a connection may be reused, default `14400`/4 hours (Grafana v5.4+).
 *Version* | This option determines which functions are available in the query builder (only available in Grafana 5.3+).
 *TimescaleDB* | TimescaleDB is a time-series database built as a PostgreSQL extension. If enabled, Grafana will use `time_bucket` in the `$__timeGroup` macro and display TimescaleDB specific aggregate functions in the query builder (only available in Grafana 5.3+).
 
@@ -377,9 +377,9 @@ datasources:
       password: "Password!"
     jsonData:
       sslmode: "disable" # disable/require/verify-ca/verify-full
-      maxOpenConns: 0
-      maxIdleConns: 2
-      connMaxLifetime: 14400
+      maxOpenConns: 0         # Grafana v5.4+
+      maxIdleConns: 2         # Grafana v5.4+
+      connMaxLifetime: 14400  # Grafana v5.4+
       postgresVersion: 903 # 903=9.3, 904=9.4, 905=9.5, 906=9.6, 1000=10
       timescaledb: false
 ```