PRTG Manual: PostgreSQL Sensor

.NET Framework

This sensor requires the Microsoft .NET Framework. .NET 4.7.2 or later must be installed on the probe system (on every cluster node, if on a cluster probe).

If the framework is missing, you cannot create this sensor.

For more information, see the Knowledge Base: Which .NET version does PRTG require?

SQL Query File

Select the SQL query file that includes a valid SQL statement that the sensor executes on the server with every scanning interval. The list contains SQL scripts from the \Custom Sensors\sql subfolder of the PRTG program directory on the probe system. Store your script there. If you use the script on a cluster probe, you must store the script on all cluster nodes.

A correct expression in the file could be: SELECT AVG(UnitPrice) FROM Products. If you want to use transactions, separate the individual steps with semicolons ";".

Note that with each request, PRTG transfers the full result set, so use filters and limits in your query.

The demo script Demo Serveruptime.sql is available by default. You can use the it to monitor the uptime of the target server.

See also the Knowledge Base: Why do I have to store SQL sensor queries and custom scripts in files on the probe computer?

Data Processing

Define whether the sensor processes data from the database:

• Only execute query: Only show information about the number of affected rows and the execution time of the query. Affected rows are rows that were changed by the query (for example, created, deleted, or edited).
• Count table rows: Execute a SELECT statement and monitor how many rows of the data table this statement returns.
• Process data table: Read and analyze the data table. If you select this option, the sensor counts rows with SELECT statements as well.

Channel #2 - #10

This setting is only visible if you select Process data table above. You can define up to 10 additional channels for the data processing of this sensor. You have to define at least one data channel if you process the data table, so you automatically see all available settings for Channel #1. Specify how to handle all other possible channels:

• Disable: Do not create this channel.
• Enable: Create this channel.

It is not possible to enable or disable channels after sensor creation.

Channel #x Name

This setting is only visible if you select Process data table above. Enter a unique name for the channel. Enter a string. PRTG dynamically generates channels with this name as the identifier.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Channel #x Mode

This setting is only visible if you select Process data table above. Define how to display the determined value in the channel:

• Absolute (recommended): Show the value as the sensor retrieves it from the data table.
• Difference: The sensor calculates and shows the difference between the last and the current value returned from the data table.
  This mode is not compatible with the unit Lookup.
   
  This mode only works if the difference between the last and the current value is positive and increases with each scanning interval. This mode does not support negative and decreasing values.

Channel #x Unit

This setting is only visible if you select Process data table above. Define the unit of the channel value:

• BytesBandwidth
• BytesMemory
• BytesDisk
• Temperature
• Percent
• TimeResponse
• TimeSeconds
• TimeHours
• Count
• CPU
• BytesFile
• SpeedDisk
• SpeedNet
• Custom
• Lookup

For more information about the available units, see section Custom Sensors.

To use lookups with this channel, select Lookup and define the lookup file in Channel #x Lookup. Do not use Custom if you use lookups with this sensor.

It is not possible to use the unit Lookup in combination with the Difference mode. You are not able to create the sensor in this case.

Sensor Name

Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Parent Tags

Shows tags that the sensor inherits from its parent device, parent group, and parent probe.

This setting is for your information only. You cannot change it.

Tags

Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.

It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

For performance reasons, it can take some minutes until you can filter for new tags that you added.

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

• sqlsensor

Priority

Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority () to the highest priority ().

Database

Enter the name of the PostgreSQL database to which the sensor connects, for example MyDatabase. This is a logical entity on the database server where database objects exist.

SSL Mode

Select the PostgreSQL Secure Sockets Layer (SSL) mode for the connection:

• Disable: Do not use SSL.
• Allow: Use SSL if the server demands it.
• Prefer: Use SSL if the server supports it.
• Require: Always use SSL and deny the connection if the server does not support it.

The SSL mode options that you can choose are the same as the values of the PostgreSQL sslmode parameter. PRTG sends it with the sensor requests.

PostgreSQL SSL connections require OpenSSL to be installed on both the target server and on the probe system.

For details about the PostgreSQL SSL modes, refer to the PostgreSQL documentation.

SQL Query File

Shows the SQL script file that the sensor executes on the server.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Input Parameter Handling

Define if you want to pass a parameter to the SQL query file:

• Do not use input parameter (default): Execute the SQL query file without using variables.
• Use input parameter: Execute an SQL query file that contains a variable. Provide the parameter that you want to use in the query below.

Input Parameter

This setting is only visible if you select Input Parameter Handling above. Enter the parameter that you want to pass to the SQL query file. This parameter replaces the variables @prtg, :prtg, or ? in the SQL query, considering the general rules for SQL variables.

You can also use PRTG placeholders for custom sensors (command-line parameters) as input parameters, for example, %sensorid or %deviceid. For details, see section Custom Sensors.

Provide strings as they are and do not surround them with quotation marks. PRTG automatically and correctly inserts string parameters into the query.

Transaction Handling

Define if you want to use transactions and if they affect the database content:

• Do not use transaction (default): Do not execute transactions.
• Use transaction and always roll back: The query does not change data in the database. In the SQL query file, separate the single steps of the transaction with semicolons.
• Use transaction and commit on success: The query changes data in the database. The changes only apply if all execution steps succeed without any errors. In the SQL query file, separate the single steps of the transaction with semicolons.

Data Processing

Shows how the sensor processes data from the database.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Handle DBNull in Channel Values as

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. Define the sensor behavior if the query returns DBNull:

• Error: Show a Down status if the query returns DBNull.
• Number 0: Recognize the result DBNull as a valid value and interpret it as the number 0.

Select Channel Value by

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. Define how to select the desired cell in the database table:

• Column number: Determine the channel value by using the value in row 0 of the column whose number you specify in Channel #x Column Number.
• Column name: Determine the channel value by using the value in row 0 of the column whose name you specify in Channel #x Column Name.
• Row number: Determine the channel value by using the value in column 0 of the row whose number you specify in Channel #x Row Number.
• Key value pair: Determine the channel value by searching in column 0 for the key you specify in Channel #x Key and by returning the value in column 1 of the same row where the key value was found.

Defining how the desired cell in the database table is selected is necessary to configure the cells that are used in the channels.

The option you select here also defines the method of how to optionally determine a value for the sensor message. For details, see setting Use Data Table Value in Sensor Message.

For an example for channel value selection, see section Monitoring Databases.

Channel #x

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. The setting shows if the channel is disabled.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Channel #x Name

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. Enter a unique name for the channel. Enter a string. The sensor dynamically generates channels with this name as identifier.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Channel #x Column Number

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation and if you select Column number for the setting Select Channel Value by. Provide the number of the column to use to determine the channel value in row 0. Enter an integer value.

Channel #x Column Name

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation and if you select Column name for the setting Select Channel Value by. Provide the name of the column to use to determine the channel value in row 0. Enter an integer value.

Channel #x Row Number

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation and if you select Row number for the setting Select Channel Value by. Provide the number of the column to use to determine the channel value in row 0. Enter an integer value.

Channel #x Mode

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. The setting shows how you want to display the determined value in the channel.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Channel #x Unit

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. Define the unit of the channel value:

• BytesBandwidth
• BytesMemory
• BytesDisk
• Temperature
• Percent
• TimeResponse
• TimeSeconds
• TimeHours
• Count
• CPU
• BytesFile
• SpeedDisk
• SpeedNet
• Custom
• Lookup

Channel #x Custom Unit

This setting is only visible if you select the channel unit Custom above. Define a unit for the channel value. Enter a string.

Channel #x Lookup

This setting is only visible if you select the channel unit Lookup above. Select a lookup file that you want to use with this channel.

Use Data Table Value in Sensor Message

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation. Define if the sensor message shows a value from the data table:

• Disable: Do not use a custom sensor message.
• Enable: Define a custom sensor message with a defined value of the data table. Define the value selection below.

The method of how to determine a value for the sensor message is defined in the setting Select Channel Value by above.

Sensor Message Column Number

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation, if you select Column number for the setting Select Channel Value by, and if you enable Use Data Table Value in Sensor Message. Enter the number of a column. The sensor message shows the value in row 0 of this column. Enter an integer value.

Sensor Message Column Name

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation, if you select Column name for the setting Select Channel Value by, and if you enable Use Data Table Value in Sensor Message. Enter the name of a column. The sensor message shows the value in row 0 of this column. Enter a string.

Columns start with index 0.

Sensor Message Row Number

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation, if you select Row number for the setting Select Channel Value by, and if you enable Use Data Table Value in Sensor Message. Enter the name of a column. The sensor message shows the value in row 0 of this column. Enter the number of a row. The sensor message shows the value in column 0 of this row. Enter an integer value.

Rows start with index 0.

Sensor Message Key

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation, if you select Key value pair for the setting Select Channel Value by, and if you enable Use Data Table Value in Sensor Message. Enter a key to search for in column 0 of the data table. The sensor message shows the value in column 1 of the row where the key was found. Enter a string.

Sensor Message

This setting is only visible if you enable Use Data Table Value in Sensor Message. Define the sensor message. Enter a string. Use the placeholder {0} at the position where you want to display the value.

Example: The message is {0}

The number sign (#) is not supported in sensor messages. If a message contains a number sign, the message is clipped at this point.

If Sensor Message Changes

This setting is only visible if you select Process data table for the setting Data Processing during sensor creation.

Define what the sensor does when the sensor message changes:

• Ignore changes (default): Take no action on change.
• Trigger 'change' notification: Send an internal message indicating that the sensor value has changed. In combination with a change trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.

Result Handling

Define what PRTG does with the sensor result:

• Discard result: Do not store the sensor result.

• Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt, Result of Sensor [ID].Data.txt, and Result of Sensor [ID].log. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.

In a cluster, PRTG stores the result in the PRTG data directory of the master node.

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

• Show channels independently (default): Show a graph for each channel.
• Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
  You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Scanning Interval

Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:

• 30 seconds
• 60 seconds
• 5 minutes
• 10 minutes
• 15 minutes
• 30 minutes
• 1 hour
• 4 hours
• 6 hours
• 12 hours
• 24 hours

You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from:

• Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails.
• Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status.
• Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails.
• Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails.
• Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails.
• Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails.

Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show the Down status. It is not possible to immediately set a WMI sensor to the Down status, so the first option does not apply to these sensors. All other options can apply.

If you define error limits for a sensor's channels, the sensor immediately shows the Down status. None of the interval options apply.

If a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.

Schedule

Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:

• None
• Saturdays
• Sundays
• Weekdays
• Weekdays Eight-To-Eight (08:00 - 20:00)
• Weekdays Nights (17:00 - 09:00)
• Weekdays Nights (20:00 - 08:00)
• Weekdays Nine-To-Five (09:00 - 17:00)
• Weekends

You can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Schedules.

Maintenance Window

Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:

• Do not set up a one-time maintenance window: Do not set up a one-time maintenance window. Monitoring is always active.
• Set up a one-time maintenance window: Set up a one-time maintenance window and pause monitoring. You can define a time span for the pause below.

To terminate an active maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the one-time maintenance window.

Maintenance Ends

This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the one-time maintenance window.

Dependency Type

Select a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:

• Use parent: Use the dependency type of the parent object.
• Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in the Down status or in the Paused status because of another dependency.

• Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in the Down status, the device is paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor is paused if the parent group is paused by another dependency.

To test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

Dependency

This setting is only visible if you enable Select a sensor above. Click and use the object selector to select a sensor on which the current object will depend.

Dependency Delay (Sec.)

This setting is only visible if you enable Select a sensor above. Define a time span in seconds for the dependency delay.

After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.

This setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent device settings or in its parent group settings.

User Group Access

Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:

• Inherited: Inherit the access rights settings of the parent object.
• No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree.
• Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
• Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
• Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

For more details on access rights, see section Access Rights Management.

Channel Unit Types

For each type of channel, select the unit in which PRTG displays the data. If you define this setting on probe, group, or device level, you can inherit these settings to all sensors underneath. You can set units for the following channel types (if available):

• Bandwidth
• Memory
• Disk
• File
• Custom

Custom channel types are only available on sensor level.

Affected Rows

The number of rows that were addressed by the query (including SELECT statements if you process data tables)

Execution Time

The execution time of the entire request (including connection buildup, query execution, transaction handling, disconnection) in milliseconds (msec)

This channel is the primary channel by default.

Downtime

In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status in percent.

Query Execution Time

The execution time of the specified query in msec