Query examples

Note: You will notice that PQL queries are written with indentation and capitalization throughout the documentation. This is not a requirement of PQL, but to make them easier to read. In fact, PQL does not require indentation, is not case sensitive, and supports alternative structures.

Query 1: Simple selection

Query 1 asks Paglo to display all the information it has at the device level:

SELECT *
FROM /network/device

Since the first item in the SELECT clause is a * star, this query returns the entire subtree that matches the search criteria. The FROM clause references an absolute path /network/device in the tree.

The results themselves are trees. PQL generates a hitlist in a YAML-like structure that shows relationship structure with one or more indents, sequenced items with dashes, and key value pairs with colons. A scalar value returns itself. Specific subtrees return the sub-trees. Sub-trees are treated like rows in a SQL table.

When run against the sample database, this query finds all 6 devices in the database, and reports all of the corresponding data about each device:

row 
  * 
    network 
      device 
        system 
          name 5627 
          computed_vendor LANIER 
          computed_model 5627 
          computed_class printer 
          computed_score 115 
        os 
          version LANIER 5627 5.20 
        interface 
          name eth0 
          mac_address 01:01:02:03:04:05 
          in_octets 1995335536 
          out_octets 248342455 
          oper_status 1 
      device 
        system 
          name ESMITH 
          computed_vendor Intel 
          computed_class server 
          computed_score 10 
        os 
          version Linux 
        interface 
          name eth0 
          mac_address 02:A1:A2:A3:A4:A4 
          in_octets 1229592351 
          out_octets 1472928781 
          oper_status 1 
        interface 
          nameeth1 
          mac_address 03:A1:A2:A3:A4:A5 
          in_octets 0 
          out_octets 0 
          oper_status 0 
      device 
        system 
          name AJONES 
          computed_vendor Intel 
          computed_class server 
          computed_score 10 
        os 
          version Linux 
        interface 
          name eth0 
          mac_address 04:A1:A2:A3:A4:A8 
          in_octets 1223098455 
          out_octets 1523093749 
          oper_status 1 
        interface 
          name eth1 
          mac_address 05:A1:A2:A3:A4:A9 
          in_octets 0 
          out_octets 0 
          oper_status 0 
      device 
        system 
          computed_model Ethernet Switch 
          computed_class switch 
          computed_score 25 
        os 
          version Ethernet Switch 
        interface 
          name eth0 
          mac_address 06:13:72:F3:0A:F5 
          in_octets 0 
          out_octets 0 
          oper_status 2 
        interface 
          name eth1 
          mac_address 07:13:72:F3:0A:F6 
          in_octets 0 
          out_octets 0 
          oper_status 2 
      device 
        system 
          name KRYPTON 
          computed_model Windows Workstation 
          computed_class workstation 
          computed_score 125 
        os 
          version Darwin Kernel Version 9.2.2 
        interface 
          name eth0 
          mac_address 08:16:CB:FF:FE:66 
          in_octets 0 
          out_octets 346 
          oper_status 1 
        interface 
          name eth1 
          mac_address 09:16:CB:FF:FE:67 
          in_octets 0 
          out_octets 0 
          oper_status 2 
        interface 
          name eth2 
          mac_address 10:16:CB:FF:FE:68 
          in_octets 0 
          out_octets 0 
          oper_status 2 
        interface 
          name eth3 
          mac_address 11:16:CB:FF:FE:69 
          in_octets 1598233842 
          out_octets 2360815490 
          oper_status 1 
      device 
        system 
          name NISSINGETTY 
          computed_vendor Juniper Networks 
          computed_model Netscreen Router 
          computed_class router 
          computed_score 60 
        os 
          version NetScreen-5GT 5.1.043a 
        interface 
          name eth0 
          mac_address 12:10:D8:99:2B:C2 
          in_octets 1385354750 
          out_octets 1451321493 
          oper_status 1 
        interface 
          name eth1 
          mac_address 13:10:D8:99:2B:C1 
          in_octets 3312952833 
          out_octets 3239791359 
          oper_status 1

Query 2: Simple restriction

Query 2 is a more specific variation of Query 1, using a WHERE clause to restrict it to find all the data about the device that has an interface with a specific MAC address:

SELECT * 
FROM /network/device
WHERE interface/mac_address = '13:10:D8:99:2B:C1'

The query returns a hitlist in the same tree form as earlier, but reports only the data about the router, since it is the only device that has an interface with a matching MAC address. Note that the MAC address limited the results to the device, not to the interface. Thus, the results include one interface with a non-matching MAC address:

row
  *
    system
          name NISSINGETTY 
          computed_vendor Juniper Networks 
          computed_model Netscreen Router 
          computed_class router 
          computed_score 60 
        os 
          version NetScreen-5GT 5.1.043a 
        interface 
          name eth0 
          mac_address 12:10:D8:99:2B:C2 
          in_octets 1385354750 
          out_octets 1451321493 
          oper_status 1 
        interface 
          name eth1 
          mac_address 13:10:D8:99:2B:C1 
          in_octets 3312952833 
          out_octets 3239791359 
          oper_status 1

Query 3: More specific restriction

Instead of selecting everything, as in Query 2, Query 3 asks for information at the interface level:

SELECT interface 
FROM /network/device
WHERE interface/mac_address = '13:10:D8:99:2B:C1'

If run against the sample database, Query 3 returns a hitlist with data about the router's two interfaces:

row
  interface
    interface
      name eth0
      mac_address 12:10:D8:99:2B:C2
      in_octets 1385354750
      out_octets 1451321493
      oper_status 1
    interface
      name eth1
      mac_address 13:10:D8:99:2B:C1
      in_octets 3312952833
      out_octets 3239791359
      oper_status 1

Query 4: Specific selection

Query 4 is narrower than Query 1. It selects only the name and MAC address of interfaces at the /network/device/interface node:

SELECT mac_address, name
FROM /network/device/interface

If run against the sample database, this query generates just the requested information about each interface. In this example, the relationships between the interfaces and the devices that they belong to is not evident:

row
  mac_address 01:01:02:03:04:05
  name eth0
row
  mac_address 02:A1:A2:A3:A4:A4
  name eth0
row
  mac_address 03:A1:A2:A3:A4:A5
  name eth1
row
  mac_address 04:A1:A2:A3:A4:A8
  name eth0
row
  mac_address 05:A1:A2:A3:A4:A9
  name eth1
row
  mac_address 06:13:72:F3:0A:F5
  name eth0
row
  mac_address 07:13:72:F3:0A:F6
  name eth1
row
  mac_address 08:16:CB:FF:FE:66
  name eth0
row
  mac_address 09:16:CB:FF:FE:67
  name eth1
row
  mac_address 10:16:CB:FF:FE:68
  name eth2
row
  mac_address 11:16:CB:FF:FE:69
  name eth3
row
  mac_address 12:10:D8:99:2B:C2
  name eth0
row
  mac_address 13:10:D8:99:2B:C1
  name eth1

Query 5: More specific selection

Unlike Query 4, Query 5 asks for the same data by making the SELECT clause more specific. This query asks for the MAC address and name of each interface, from the /network/device location:

SELECT interface/mac_address, interface/name 
FROM /network/device

If run against the sample database, this query generates the requested data about each interface. Note that the data is grouped such that the relationships between the interfaces and the devices that they belong to is somewhat evident, but the relationships between each name and each MAC address is not directly evident:

row
  interface/mac_address 01:01:02:03:04:05
  interface/name eth0
row
  interface/mac_address
    mac_address 02:A1:A2:A3:A4:A4
    mac_address 03:A1:A2:A3:A4:A5
  interface/name
    nameeth 0
    nameeth 1
row
  interface/mac_address
    mac_address 04:A1:A2:A3:A4:A8
    mac_address 05:A1:A2:A3:A4:A9
  interface/name
    nameeth 0
    nameeth 1
row
  interface/mac_address
    mac_address 06:13:72:F3:0A:F5
    mac_address 07:13:72:F3:0A:F6
  interface/name
    nameeth 0
    nameeth 1
row
  interface/mac_address
    mac_address 08:16:CB:FF:FE:66
    mac_address 09:16:CB:FF:FE:67
    mac_address 10:16:CB:FF:FE:68
    mac_address 11:16:CB:FF:FE:69
  interface/name
    name eth0
    name eth1
    name eth2
    name eth3
row
  interface/mac_address
    mac_address 12:10:D8:99:2B:C2
    mac_address 13:10:D8:99:2B:C1
  interface/name
    name eth0
    name eth1

Query 6: Specific selection with relationship

By grouping the request for MAC address and name within closed brackets, this query finds the same information as Query 4 and Query 5, but is able to retain the relationships between name and MAC address of each interface, and between interfaces and the devices they are on:

SELECT interface/(mac_address, name)                
FROM /network/device

If you run this query on the same sample database above, it generates the following results:

row
  interface/(mac_address, name)
    item
      mac_address 01:01:02:03:04:05
      name eth0
row
  interface/(mac_address, name)
    item
      mac_address 02:A1:A2:A3:A4:A4
      name eth0
    item
      mac_address 03:A1:A2:A3:A4:A5
      name eth1
row
  interface/(mac_address, name)
    item
      mac_address 04:A1:A2:A3:A4:A8
      name eth0
    item
      mac_address 05:A1:A2:A3:A4:A9
      name eth1
row
  interface/(mac_address, name)
    item
      mac_address 06:13:72:F3:0A:F5
      name eth0
    item
      mac_address 07:13:72:F3:0A:F6
      name eth1
row
  interface/(mac_address, name)
    item
      mac_address 08:16:CB:FF:FE:66
      name eth0
    item
      mac_address 09:16:CB:FF:FE:67
      name eth1
    item
      mac_address 10:16:CB:FF:FE:68
      name eth2
    item
      mac_address 11:16:CB:FF:FE:69
      name eth3
row
  interface/(mac_address, name)
    item
      mac_address 12:10:D8:99:2B:C2
      name eth0
    item
      mac_address 13:10:D8:99:2B:C1
      name eth1