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Connection load balancing policies

Connection load balancing policies help spread the load of servicing client connections by redirecting connections based on the connection's origin.

1: Creating network addresses
2: Creating connection load balance groups
3: Creating load balancing routing rules
4: Testing connection load balancing policies
5: Load balancing policy examples
6: Viewing load balancing policy configurations
7: Maintaining load balancing policies

Connection load balancing policies help spread the load of servicing client connections by redirecting connections based on the connection's origin. These policies can also help prevent nodes reaching their client connection limits and rejecting new connections by spreading connections among nodes. See Limiting the number and length of client connections for more information about client connection limits.

A load balancing policy consists of:

Network addresses that identify particular IP address and port number combinations on a node.
One or more connection load balancing groups that consists of network addresses that you want to handle client connections. You define load balancing groups using fault groups, subclusters, or a list of network addresses.
One or more routing rules that map a range of client IP addresses to a connection load balancing group.

When a client connects to a node in the database with load balancing enabled, the node evaluates all of the routing rules based on the client's IP address to determine if any match. If more than one rule matches the IP address, the node applies the most specific rule (the one that affects the fewest IP addresses).

If the node finds a matching rule, it uses the rule to determine the pool of potential nodes to handle the client connection. When evaluating potential target nodes, it always ensures that the nodes are currently up. The initially-contacted node then chooses one of the nodes in the group based on the group's distribution scheme. This scheme can be either choosing a node at random, or choosing a node in a rotating "round-robin" order. For example, in a three-node cluster, the round robin order would be node 1, then node 2, then node 3, and then back to node 1 again.

After it processes the rules, if the node determines that another node should handle the client's connection, it tells the client which node it has chosen. The client disconnects from the initial node and connects to the chosen node to continue with the connection process (either negotiating encryption if the connection has TLS/SSL enabled, or authentication).

If the initial node chooses itself based on the routing rules, it tells the client to proceed to the next step of the connection process.

If no routing rule matches the incoming IP address, the node checks to see if classic connection load balancing is enabled by both Vertica and the client. If so, it handles the connection according to the classic load balancing policy. See Classic connection load balancing for more information.

Finally, if the database is running in Eon Mode, the node tries to apply a default interior load balancing rule. See Default Subcluster Interior Load Balancing Policy below.

If no routing rule matches the incoming IP address and classic load balancing and the default subcluster interior load balancing rule did not apply, the node handles the connection itself. It also handles the connection itself if it cannot follow the load balancing rule. For example, if all nodes in the load balancing group targeted by the rule are down, then the initially-contacted node handles the client connection itself. In this case, the node does not attempt to apply any other less-restrictive load balancing rules that would apply to the incoming connection. It only attempts to apply a single load balancing rule.

Use cases

Using load balancing policies you can:

Ensure connections originating from inside or outside of your internal network are directed to a valid IP address for the client. For example, suppose your Vertica nodes have two IP addresses: one for the external network and another for the internal network. These networks are mutually exclusive. You cannot reach the private network from the public, and you cannot reach the public network from the private. Your load balancing rules need to provide the client with an IP address they can actually reach.
Enable access to multiple nodes of a Vertica cluster that are behind a NAT router. A NAT router is accessible from the outside network via a single IP address. Systems within the NAT router's private network can be accessed on this single IP address using different port numbers. You can create a load balancing policy that redirects a client connection to the NAT's IP address but with a different port number.
Designate sets of nodes to service client connections from an IP address range. For example, if your ETL systems have a set range of IP addresses, you could limit their client connections to an arbitrary set of Vertica nodes, a subcluster, or a fault group. This technique lets you isolate the overhead of servicing client connections to a few nodes. It is useful when you are using subclusters in an Eon Mode database to isolate workloads (see Subclusters for more information).

Using connection load balancing policies with IPv4 and IPv6

Connection load balancing policies work with both IPv4 and IPv6. As far as the load balancing policies are concerned, the two address families represent separate networks. If you want your load balancing policy to handle both IPv4 and IPv6 addresses, you must create separate sets of network addresses, load balancing groups, and rules for each protocol. When a client opens a connection to a node in the cluster, the addressing protocol it uses determines which set of rules Vertica consults when deciding whether and how to balance the connection.

Default subcluster interior load balancing policy

Databases running in Eon Mode have a default connection load balancing policy that helps spread the load of handling client connections among the nodes in a subcluster. When a client connects to a node while opting into connection load balancing, the node checks for load balancing policies that apply to the client's IP address. If it does not find any applicable load balancing rule, and classic load balancing is not enabled, the node falls back to the default interior load balancing rule. This rule distributes connections among the nodes in the same subcluster as the initially-contacted node.

As with other connection load balancing policies, the nodes in the subcluster must have a network address defined for them to be eligible to handle the client connection. If no nodes in the subcluster have a network address, the node does not apply the default subcluster interior load balancing rule, and the connection is not load balanced.

This default rule is convenient when you are primarily interested in load balancing connections within each subcluster. You just create network addresses for the nodes in your subcluster. You do not need to create load balancing groups or rules. Clients that opt-in to load balancing are then automatically balanced among the nodes in the subcluster.

Interior load balancing policy with multiple network addresses

If your nodes have multiple network addresses, the default subcluster interior load balancing rule chooses the address that was created first as the target of load balancing rule. For example, suppose you create a network address on a node for the private IP address 192.168.1.10. Then you create another network address for the node for the public IP address 233.252.0.1. The default subcluster interior connection load balancing rule always selects 192.168.1.10 as the target of the rule.

If you want the default interior load balancing rule to choose a different network address as its target, drop the other network addresses on the node and then recreate them. Deleting and recreating other addresses makes the address you want the rule to select the oldest address. For example, suppose you want the rule to use a public address (233.252.0.1) that was created after a private address (192.168.1.10). In this case, you can drop the address for 192.168.1.10 and then recreate it. The rule then defaults to the older public 233.252.0.1 address.

If you intend to create multiple network addresses for the nodes in your subcluster, create the network addresses you want to use with the default subcluster interior load balancing first. For example, suppose you want to use the default interior load balancing subcluster rule to load balance most client connections. However, you also want to create a connection load balancing policy to manage connections coming in from a group of ETL systems. In this case, create the network addresses you want to use for the default interior load balancing rule first, then create the network addresses for the ETL systems.

Load balancing policies vs. classic load balancing

There are several differences between the classic load balancing feature and the load balancing policy feature:

In classic connection load balancing, you just enable the load balancing option on both client and server, and load balancing is enabled. There are more steps to implement load balancing policies: you have to create addresses, groups, and rules and then enable load balancing on the client.
Classic connection load balancing only supports a single, cluster-wide policy for redirecting connections. With connection load balancing policies, you get to choose which nodes handle client connections based on the connection's origin. This gives you more flexibility to handle complex situations. Examples include routing connections through a NAT-based router or having nodes that are accessible via multiple IP addresses on different networks.
In classic connection load balancing, each node in the cluster can only be reached via a single IP address. This address is set in the EXPORT_ADDRESS column of the NODES system table. With connection load balancing policies, you can create a network address for each IP address associated with a node. Then you create rules that redirect to those addresses.

Steps to create a load balancing policy

There are three steps you must follow to create a load balancing policy:

Create one or more network addresses for each node that you want to participate in the connection load balancing policies.
Create one or more load balancing groups to be the target of the routing rules. Load balancing groups can target a collection of specific network addresses. Alternatively, you can create a group from a fault group or subcluster. You can limit the members of the load balance group to a subset of the fault group or subcluster using an IP address filter.
Create one or more routing rules.

While not absolutely necessary, it is always a good idea to idea to test your load balancing policy to ensure it works the way you expect it to.

After following these steps, Vertica will apply the load balancing policies to client connections that opt into connection load balancing. See Load balancing in ADO.NET, Load balancing in JDBC, and Load balancing, for information on enabling load balancing on the client. For vsql, use the -C command-line option to enable load balancing.

These steps are explained in the other topics in this section.

1 - Creating network addresses

Network addresses assign a name to an IP address and port number on a node.

Network addresses assign a name to an IP address and port number on a node. You use these addresses when you define load balancing groups. A node can have multiple network addresses associated with it. For example, suppose a node has one IP address that is only accessible from outside of the local network, and another that is accessible only from inside the network. In this case, you can define one network address using the external IP address, and another using the internal address. You can then create two different load balancing policies, one for external clients, and another for internal clients.

Note

You must create network addresses for your nodes, even if you intend to base your connection load balance groups on fault groups or subclusters. Load balancing rules can only select nodes that have a network address defined for them.

You create a network address using the CREATE NETWORK ADDRESS statement. This statement takes:

The name to assign to the network address
The name of the node
The IP address of the node to associate with the network address
The port number the node uses to accept client connections (optional)

Note

You can use hostnames instead of IP addresses when creating network addresses. However, doing so may lead to confusion if you are not sure which IP address a hostname resolves to. Using hostnames can also cause problems if your DNS server maps the hostname to multiple IP addresses.

The following example demonstrates creating three network addresses, one for each node in a three-node database.

=> SELECT node_name,node_address,node_address_family FROM v_catalog.nodes;
    node_name     | node_address | node_address_family
------------------+--------------+----------------------
 v_vmart_node0001 | 10.20.110.21 | ipv4
 v_vmart_node0002 | 10.20.110.22 | ipv4
 v_vmart_node0003 | 10.20.110.23 | ipv4
(4 rows)


=> CREATE NETWORK ADDRESS node01 ON v_vmart_node0001 WITH '10.20.110.21';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02 ON v_vmart_node0002 WITH '10.20.110.22';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03 on v_vmart_node0003 WITH '10.20.110.23';
CREATE NETWORK ADDRESS

Creating network addresses for IPv6 addresses works the same way:

=> CREATE NETWORK ADDRESS node1_ipv6 ON v_vmart_node0001 WITH '2001:0DB8:7D5F:7433::';
CREATE NETWORK ADDRESS

Vertica does not perform any tests on the IP address you supply in the CREATE NETWORK ADDRESS statement. You must test the IP addresses you supply to this statement to confirm they correspond to the right node.

Vertica does not restrict the address you supply because it is often not aware of all the network addresses through which the node is accessible. For example, your node may be accessible from an external network via an IP address that Vertica is not configured to use. Or, your node can have both an IPv4 and an IPv6 address, only one of which Vertica is aware of.

For example, suppose v_vmart_node0003 from the previous example is not accessible via the IP address 192.168.1.5. You can still create a network address for it using that address:

=> CREATE NETWORK ADDRESS node04 ON v_vmart_node0003 WITH '192.168.1.5';
CREATE NETWORK ADDRESS

If you create a network group and routing rule that targets this address, client connections would either connect to the wrong node, or fail due to being connected to a host that's not part of a Vertica cluster.

Specifying a port number in a network address

By default, the CREATE NETWORK ADDRESS statement assumes the port number for the node's client connection is the default 5433. Sometimes, you may have a node listening for client connections on a different port. You can supply an alternate port number for the network address using the PORT keyword.

For example, suppose your nodes are behind a NAT router. In this case, you can have your nodes listen on different port numbers so the NAT router can route connections to them. When creating network addresses for these nodes, you supply the IP address of the NAT router and the port number the node is listening on. For example:

=> CREATE NETWORK ADDRESS node1_nat ON v_vmart_node0001 WITH '192.168.10.10' PORT 5433;
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node2_nat ON v_vmart_node0002 with '192.168.10.10' PORT 5434;
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node3_nat ON v_vmart_node0003 with '192.168.10.10' PORT 5435;
CREATE NETWORK ADDRESS

2 - Creating connection load balance groups

After you have created network addresses for nodes, you create collections of them so you can target them with routing rules.

After you have created network addresses for nodes, you create collections of them so you can target them with routing rules. These collections of network addresses are called load balancing groups. You have two ways to select the addresses to include in a load balancing group:

A list of network addresses
The name of one or more fault groups or subclusters, plus an IP address range in CIDR format. The address range selects which network addresses in the fault groups or subclusters Vertica adds to the load balancing group. Only the network addresses that are within the IP address range you supply are added to the load balance group. This filter lets you base your load balance group on a portion of the nodes that make up the fault group or subcluster.

Note

Load balance groups can only be based on fault groups or subclusters, or contain an arbitrary list of network addresses. You cannot mix these sources. For example, if you create a load balance group based on one or more fault groups, then you can only add additional fault groups to it. Vertica will return an error if you try to add a network address or subcluster to the load balance group.

You create a load balancing group using the CREATE LOAD BALANCE GROUP statement. When basing your group on a list of addresses, this statement takes the name for the group and the list of addresses. The following example demonstrates creating addresses for four nodes, and then creating two groups based on those nodes.

=> CREATE NETWORK ADDRESS addr01 ON v_vmart_node0001 WITH '10.20.110.21';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS addr02 ON v_vmart_node0002 WITH '10.20.110.22';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS addr03 on v_vmart_node0003 WITH '10.20.110.23';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS addr04 on v_vmart_node0004 WITH '10.20.110.24';
CREATE NETWORK ADDRESS
=> CREATE LOAD BALANCE GROUP group_1 WITH ADDRESS addr01, addr02;
CREATE LOAD BALANCE GROUP
=> CREATE LOAD BALANCE GROUP group_2 WITH ADDRESS addr03, addr04;
CREATE LOAD BALANCE GROUP

=> SELECT * FROM LOAD_BALANCE_GROUPS;
    name    |   policy   |     filter      |         type          | object_name
------------+------------+-----------------+-----------------------+-------------
 group_1    | ROUNDROBIN |                 | Network Address Group | addr01
 group_1    | ROUNDROBIN |                 | Network Address Group | addr02
 group_2    | ROUNDROBIN |                 | Network Address Group | addr03
 group_2    | ROUNDROBIN |                 | Network Address Group | addr04
(4 rows)

A network address can be a part of as many load balancing groups as you like. However, each group can only have a single network address per node. You cannot add two network addresses belonging to the same node to the same load balancing group.

Creating load balancing groups from fault groups

To create a load balancing group from one or more fault groups, you supply:

The name for the load balancing group
The name of one or more fault groups
An IP address filter in CIDR format that filters the fault groups to be added to the load balancing group basd on their IP addresses. Vertica excludes any network addresses in the fault group that do not fall within this range. If you want all of the nodes in the fault groups to be added to the load balance group, specify the filter 0.0.0.0/0.

This example creates two load balancing groups from a fault group. The first includes all network addresses in the group by using the CIDR notation for all IP addresses. The second limits the fault group to three of the four nodes in the fault group by using the IP address filter.

=> CREATE FAULT GROUP fault_1;
CREATE FAULT GROUP
=> ALTER FAULT GROUP fault_1 ADD NODE  v_vmart_node0001;
ALTER FAULT GROUP
=> ALTER FAULT GROUP fault_1 ADD NODE  v_vmart_node0002;
ALTER FAULT GROUP
=> ALTER FAULT GROUP fault_1 ADD NODE  v_vmart_node0003;
ALTER FAULT GROUP
=> ALTER FAULT GROUP fault_1 ADD NODE  v_vmart_node0004;
ALTER FAULT GROUP
=> SELECT node_name,node_address,node_address_family,export_address
   FROM v_catalog.nodes;
    node_name     | node_address | node_address_family | export_address
------------------+--------------+---------------------+----------------
 v_vmart_node0001 | 10.20.110.21 | ipv4                | 10.20.110.21
 v_vmart_node0002 | 10.20.110.22 | ipv4                | 10.20.110.22
 v_vmart_node0003 | 10.20.110.23 | ipv4                | 10.20.110.23
 v_vmart_node0004 | 10.20.110.24 | ipv4                | 10.20.110.24
(4 rows)

=> CREATE LOAD BALANCE GROUP group_all WITH FAULT GROUP fault_1 FILTER
   '0.0.0.0/0';
CREATE LOAD BALANCE GROUP

=> CREATE LOAD BALANCE GROUP group_some WITH FAULT GROUP fault_1 FILTER
   '10.20.110.21/30';
CREATE LOAD BALANCE GROUP

=> SELECT * FROM LOAD_BALANCE_GROUPS;
      name      |   policy   |     filter      |         type          | object_name
----------------+------------+-----------------+-----------------------+-------------
 group_all      | ROUNDROBIN | 0.0.0.0/0       | Fault Group           | fault_1
 group_some     | ROUNDROBIN | 10.20.110.21/30 | Fault Group           | fault_1
(2 rows)

You can also supply multiple fault groups to the CREATE LOAD BALANCE GROUP statement:

=> CREATE LOAD BALANCE GROUP group_2_faults WITH FAULT GROUP
   fault_2, fault_3 FILTER '0.0.0.0/0';
CREATE LOAD BALANCE GROUP

Note

If you supply a filter range that does not match any network addresses of the nodes in the fault groups, Vertica creates an empty load balancing group. Any routing rules that direct connections to the empty load balance group will fail, because no nodes are set to handle connections for the group. In this case, the node that the client connected to initially handles the client connection itself.

Creating load balance groups from subclusters

Creating a load balance group from a subcluster is similar to creating a load balance group from a fault group. You just use WITH SUBCLUSTER instead of WITH FAULT GROUP in the CREATE LOAD BALANCE GROUP statement.

=> SELECT node_name,node_address,node_address_family,subcluster_name
   FROM v_catalog.nodes;
      node_name       | node_address | node_address_family |  subcluster_name
----------------------+--------------+---------------------+--------------------
 v_verticadb_node0001 | 10.11.12.10  | ipv4                | load_subcluster
 v_verticadb_node0002 | 10.11.12.20  | ipv4                | load_subcluster
 v_verticadb_node0003 | 10.11.12.30  | ipv4                | load_subcluster
 v_verticadb_node0004 | 10.11.12.40  | ipv4                | analytics_subcluster
 v_verticadb_node0005 | 10.11.12.50  | ipv4                | analytics_subcluster
 v_verticadb_node0006 | 10.11.12.60  | ipv4                | analytics_subcluster
(6 rows)

=> CREATE NETWORK ADDRESS node01 ON v_verticadb_node0001 WITH '10.11.12.10';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02 ON v_verticadb_node0002 WITH '10.11.12.20';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03 ON v_verticadb_node0003 WITH '10.11.12.30';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node04 ON v_verticadb_node0004 WITH '10.11.12.40';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node05 ON v_verticadb_node0005 WITH '10.11.12.50';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node06 ON v_verticadb_node0006 WITH '10.11.12.60';
CREATE NETWORK ADDRESS

=> CREATE LOAD BALANCE GROUP load_subcluster WITH SUBCLUSTER load_subcluster
   FILTER '0.0.0.0/0';
CREATE LOAD BALANCE GROUP
=> CREATE LOAD BALANCE GROUP analytics_subcluster WITH SUBCLUSTER
   analytics_subcluster FILTER '0.0.0.0/0';
CREATE LOAD BALANCE GROUP

Setting the group's distribution policy

A load balancing group has a policy setting that determines how the initially-contacted node chooses a target from the group. CREATE LOAD BALANCE GROUP supports three policies:

ROUNDROBIN (default) rotates among the available members of the load balancing group. The initially-contacted node keeps track of which node it chose last time, and chooses the next one in the cluster.

Note
Each node in the cluster maintains its own round-robin pointer that indicates which node it should pick next for each load-balancing group. Therefore, if clients connect to different initial nodes, they may be redirected to the same node.
RANDOM chooses an available node from the group randomly.
NONE disables load balancing.

The following example demonstrates creating a load balancing group with a RANDOM distribution policy.

=> CREATE LOAD BALANCE GROUP group_random WITH ADDRESS node01, node02,
   node03, node04 POLICY 'RANDOM';
CREATE LOAD BALANCE GROUP

The next step

After creating the load balancing group, you must add a load balancing routing rule that tells Vertica how incoming connections should be redirected to the groups. See Creating load balancing routing rules.

3 - Creating load balancing routing rules

Once you have created one or more connection load balancing groups, you are ready to create load balancing routing rules.

Once you have created one or more connection load balancing groups, you are ready to create load balancing routing rules. These rules tell Vertica how to redirect client connections based on their IP addresses.

You create routing rules using the CREATE ROUTING RULE statement. You pass this statement:

The name for the rule
The source IP address range (either IPv4 or IPv6) in CIDR format the rule applies to
The name of the load balancing group to handle the connection

The following example creates two rules. The first redirects connections coming from the IP address range 192.168.1.0 through 192.168.1.255 to a load balancing group named group_1. The second routes connections from the IP range 10.20.1.0 through 10.20.1.255 to the load balancing group named group_2.

=> CREATE ROUTING RULE internal_clients ROUTE '192.168.1.0/24' TO group_1;
CREATE ROUTING RULE

=> CREATE ROUTING RULE external_clients ROUTE '10.20.1.0/24' TO group_2;
CREATE ROUTING RULE

Creating a catch-all routing rule

Vertica applies routing rules in most specific to least specific order. This behavior lets you create a "catch-all" rule that handles all incoming connections. Then you can create rules to handle smaller IP address ranges for specific purposes. For example, suppose you wanted to create a catch-all rule that worked with the rules created in the previous example. Then you can create a new rule that routes 0.0.0.0/0 (the CIDR notation for all IP addresses) to a group that should handle connections that aren't handled by either of the previously-created rules. For example:

=> CREATE LOAD BALANCE GROUP group_all WITH ADDRESS node01, node02, node03, node04;
CREATE LOAD BALANCE GROUP

=> CREATE ROUTING RULE catch_all ROUTE '0.0.0.0/0' TO group_all;
CREATE ROUTING RULE

After running the above statements, any connection that does not originate from the IP address ranges 192.168.1.* or 10.20.1.* are routed to the group_all group.

4 - Testing connection load balancing policies

After creating your routing rules, you should test them to verify that they perform the way you expect.

After creating your routing rules, you should test them to verify that they perform the way you expect. The best way to test your rules is to call the DESCRIBE_LOAD_BALANCE_DECISION function with an IP address. This function evaluates the routing rules and reports back how Vertica would route a client connection from the IP address. It uses the same logic that Vertica uses when handling client connections, so the results reflect the actual connection load balancing result you will see from client connections. It also reflects the current state of the your Vertica cluster, so it will not redirect connections to down nodes.

The following example demonstrates testing a set of rules. One rule handles all connections from the range 192.168.1.0 to 192.168.1.255, while the other handles all connections originating from the 192 subnet. The third call demonstrates what happens when no rules apply to the IP address you supply.

=> SELECT describe_load_balance_decision('192.168.1.25');
                        describe_load_balance_decision
--------------------------------------------------------------------------------
 Describing load balance decision for address [192.168.1.25]
Load balance cache internal version id (node-local): [2]
Considered rule [etl_rule] source ip filter [10.20.100.0/24]... input address
does not match source ip filter for this rule.
Considered rule [internal_clients] source ip filter [192.168.1.0/24]... input
address matches this rule
Matched to load balance group [group_1] the group has policy [ROUNDROBIN]
number of addresses [2]
(0) LB Address: [10.20.100.247]:5433
(1) LB Address: [10.20.100.248]:5433
Chose address at position [1]
Routing table decision: Success. Load balance redirect to: [10.20.100.248] port [5433]

(1 row)

=> SELECT describe_load_balance_decision('192.168.2.25');
                        describe_load_balance_decision
--------------------------------------------------------------------------------
 Describing load balance decision for address [192.168.2.25]
Load balance cache internal version id (node-local): [2]
Considered rule [etl_rule] source ip filter [10.20.100.0/24]... input address
does not match source ip filter for this rule.
Considered rule [internal_clients] source ip filter [192.168.1.0/24]... input
address does not match source ip filter for this rule.
Considered rule [subnet_192] source ip filter [192.0.0.0/8]... input address
matches this rule
Matched to load balance group [group_all] the group has policy [ROUNDROBIN]
number of addresses [3]
(0) LB Address: [10.20.100.247]:5433
(1) LB Address: [10.20.100.248]:5433
(2) LB Address: [10.20.100.249]:5433
Chose address at position [1]
Routing table decision: Success. Load balance redirect to: [10.20.100.248] port [5433]

(1 row)

=> SELECT describe_load_balance_decision('1.2.3.4');
                         describe_load_balance_decision
--------------------------------------------------------------------------------
 Describing load balance decision for address [1.2.3.4]
Load balance cache internal version id (node-local): [2]
Considered rule [etl_rule] source ip filter [10.20.100.0/24]... input address
does not match source ip filter for this rule.
Considered rule [internal_clients] source ip filter [192.168.1.0/24]... input
address does not match source ip filter for this rule.
Considered rule [subnet_192] source ip filter [192.0.0.0/8]... input address
does not match source ip filter for this rule.
Routing table decision: No matching routing rules: input address does not match
any routing rule source filters. Details: [Tried some rules but no matching]
No rules matched. Falling back to classic load balancing.
Classic load balance decision: Classic load balancing considered, but either
the policy was NONE or no target was available. Details: [NONE or invalid]

(1 row)

The DESCRIBE_LOAD_BALANCE_DECISION function also takes into account the classic cluster-wide load balancing settings:

=>  SELECT SET_LOAD_BALANCE_POLICY('ROUNDROBIN');
                            SET_LOAD_BALANCE_POLICY
--------------------------------------------------------------------------------
 Successfully changed the client initiator load balancing policy to: roundrobin
(1 row)

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('1.2.3.4');
                            describe_load_balance_decision
--------------------------------------------------------------------------------
 Describing load balance decision for address [1.2.3.4]
Load balance cache internal version id (node-local): [2]
Considered rule [etl_rule] source ip filter [10.20.100.0/24]... input address
does not match source ip filter for this rule.
Considered rule [internal_clients] source ip filter [192.168.1.0/24]... input
address does not match source ip filter for this rule.
Considered rule [subnet_192] source ip filter [192.0.0.0/8]... input address
does not match source ip filter for this rule.
Routing table decision: No matching routing rules: input address does not
match any routing rule source filters. Details: [Tried some rules but no matching]
No rules matched. Falling back to classic load balancing.
Classic load balance decision: Success. Load balance redirect to: [10.20.100.247]
port [5433]

(1 row)

Note

The DESCRIBE_LOAD_BALANCE_DECISION function assumes the client connection has opted to be load balanced. In reality, clients may not enable load balancing. This setting prevents the load-balancing features from redirecting the connection.

The function can also help you debug connection issues you notice after going live with your load balancing policy. For example, if you notice that one node is handling a large number of client connections, you can test the client IP addresses against your policies to see why the connections are not being balanced.

5 - Load balancing policy examples

The following examples demonstrate some common use cases for connection load balancing policies.

Enabling client connections from multiple networks

Suppose you have a Vertica cluster that is accessible from two (or more) different networks. Some examples of this situation are:

You have an internal and an external network. In this configuration, your database nodes usually have two or more IP addresses, which each address only accessible from one of the networks. This configuration is common when running Vertica in a cloud environment. In many cases, you can create a catch-all rule that applies to all IP addresses, and then add additional routing rules for the internal subnets.
You want clients to be load balanced whether they use IPv4 or IPv6 protocols. From the database's perspective, IPv4 and IPv6 connections are separate networks because each node has a separate IPv4 and IPv6 IP address.

When creating a load balancing policy for a database that is accessible from multiple networks, client connections must be directed to IP addresses on the network they can access. The best solution is to create load balancing groups for each set of IP addresses assigned to a node. Then create routing rules that redirect client connections to the IP addresses that are accessible from their network.

The following example:

Creates two sets of network addresses: one for the internal network and another for the external network.
Creates two load balance groups: one for the internal network and one for the external.
Creates three routing rules: one for the internal network, and two for the external. The internal routing rule covers a subset of the network covered by one of the external rules.
Tests the routing rules using internal and external IP addresses.

=> CREATE NETWORK ADDRESS node01_int ON v_vmart_node0001 WITH '192.168.0.1';
CREATE NETWORK ADDRESS

=> CREATE NETWORK ADDRESS node01_ext ON v_vmart_node0001 WITH '203.0.113.1';
CREATE NETWORK ADDRESS

=> CREATE NETWORK ADDRESS node02_int ON v_vmart_node0002 WITH '192.168.0.2';
CREATE NETWORK ADDRESS

=> CREATE NETWORK ADDRESS node02_ext ON v_vmart_node0002 WITH '203.0.113.2';
CREATE NETWORK ADDRESS

=> CREATE NETWORK ADDRESS node03_int ON v_vmart_node0003 WITH '192.168.0.3';
CREATE NETWORK ADDRESS

=> CREATE NETWORK ADDRESS node03_ext ON v_vmart_node0003 WITH '203.0.113.3';
CREATE NETWORK ADDRESS

=> CREATE LOAD BALANCE GROUP internal_group WITH ADDRESS node01_int, node02_int, node03_int;
CREATE LOAD BALANCE GROUP

=> CREATE LOAD BALANCE GROUP external_group WITH ADDRESS node01_ext, node02_ext, node03_ext;
CREATE LOAD BALANCE GROUP

=> CREATE ROUTING RULE internal_rule ROUTE '192.168.0.0/24' TO internal_group;
CREATE ROUTING RULE

=> CREATE ROUTING RULE external_rule ROUTE '0.0.0.0/0' TO external_group;
CREATE ROUTING RULE

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('198.51.100.10');
                         DESCRIBE_LOAD_BALANCE_DECISION
-------------------------------------------------------------------------------
 Describing load balance decision for address [198.51.100.10]
Load balance cache internal version id (node-local): [3]
Considered rule [internal_rule] source ip filter [192.168.0.0/24]... input
address does not match source ip filter for this rule.
Considered rule [external_rule] source ip filter [0.0.0.0/0]... input
address matches this rule
Matched to load balance group [external_group] the group has policy [ROUNDROBIN]
number of addresses [3]
(0) LB Address: [203.0.113.1]:5433
(1) LB Address: [203.0.113.2]:5433
(2) LB Address: [203.0.113.3]:5433
Chose address at position [2]
Routing table decision: Success. Load balance redirect to: [203.0.113.3] port [5433]

(1 row)

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('198.51.100.10');

                         DESCRIBE_LOAD_BALANCE_DECISION
-------------------------------------------------------------------------------
 Describing load balance decision for address [192.168.0.79]
Load balance cache internal version id (node-local): [3]
Considered rule [internal_rule] source ip filter [192.168.0.0/24]... input
address matches this rule
Matched to load balance group [internal_group] the group has policy [ROUNDROBIN]
number of addresses [3]
(0) LB Address: [192.168.0.1]:5433
(1) LB Address: [192.168.0.3]:5433
(2) LB Address: [192.168.0.2]:5433
Chose address at position [2]
Routing table decision: Success. Load balance redirect to: [192.168.0.2] port
[5433]

(1 row)

Isolating workloads

You may want to control which nodes in your cluster are used by specific types of clients. For example, you may want to limit clients that perform data-loading tasks to one set of nodes, and reserve the rest of the nodes for running queries. This separation of workloads is especially common for Eon Mode databases. See Controlling Where a Query Runs for an example of using load balancing policies in an Eon Mode database to control which subcluster a client connects to.

You can create client load balancing policies that support workload isolation if clients performing certain types of tasks always originate from a limited IP address range. For example, if the clients that load data into your system always fall into a specific subnet, you can create a policy that limits which nodes those clients can access.

In the following example:

There are two fault groups (group_a and group_b) that separate workloads in an Eon Mode database. These groups are used as the basis of the load balancing groups.
The ETL client connections all originate from the 203.0.113.0/24 subnet.
User connections originate in the range of 192.0.0.0 to 199.255.255.255.

=> CREATE NETWORK ADDRESS node01 ON v_vmart_node0001 WITH '192.0.2.1';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02 ON v_vmart_node0002 WITH '192.0.2.2';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03 ON v_vmart_node0003 WITH '192.0.2.3';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node04 ON v_vmart_node0004 WITH '192.0.2.4';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node05 ON v_vmart_node0005 WITH '192.0.2.5';
CREATE NETWORK ADDRESS
                                                     ^
=> CREATE LOAD BALANCE GROUP lb_users WITH FAULT GROUP group_a FILTER '192.0.2.0/24';
CREATE LOAD BALANCE GROUP
=> CREATE LOAD BALANCE GROUP lb_etl WITH FAULT GROUP group_b FILTER '192.0.2.0/24';
CREATE LOAD BALANCE GROUP
=> CREATE ROUTING RULE users_rule ROUTE '192.0.0.0/5' TO lb_users;
CREATE ROUTING RULE
=> CREATE ROUTING RULE etl_rule ROUTE '203.0.113.0/24' TO lb_etl;
CREATE ROUTING RULE

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('198.51.200.129');
                          DESCRIBE_LOAD_BALANCE_DECISION
-------------------------------------------------------------------------------
 Describing load balance decision for address [198.51.200.129]
Load balance cache internal version id (node-local): [6]
Considered rule [etl_rule] source ip filter [203.0.113.0/24]... input address
does not match source ip filter for this rule.
Considered rule [users_rule] source ip filter [192.0.0.0/5]... input address
matches this rule
Matched to load balance group [lb_users] the group has policy [ROUNDROBIN]
number of addresses [3]
(0) LB Address: [192.0.2.1]:5433
(1) LB Address: [192.0.2.2]:5433
(2) LB Address: [192.0.2.3]:5433
Chose address at position [1]
Routing table decision: Success. Load balance redirect to: [192.0.2.2] port
[5433]

(1 row)

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('203.0.113.24');
                             DESCRIBE_LOAD_BALANCE_DECISION
-------------------------------------------------------------------------------
 Describing load balance decision for address [203.0.113.24]
Load balance cache internal version id (node-local): [6]
Considered rule [etl_rule] source ip filter [203.0.113.0/24]... input address
matches this rule
Matched to load balance group [lb_etl] the group has policy [ROUNDROBIN] number
of addresses [2]
(0) LB Address: [192.0.2.4]:5433
(1) LB Address: [192.0.2.5]:5433
Chose address at position [1]
Routing table decision: Success. Load balance redirect to: [192.0.2.5] port
[5433]

(1 row)

=> SELECT DESCRIBE_LOAD_BALANCE_DECISION('10.20.100.25');
                           DESCRIBE_LOAD_BALANCE_DECISION
-------------------------------------------------------------------------------
 Describing load balance decision for address [10.20.100.25]
Load balance cache internal version id (node-local): [6]
Considered rule [etl_rule] source ip filter [203.0.113.0/24]... input address
does not match source ip filter for this rule.
Considered rule [users_rule] source ip filter [192.0.0.0/5]... input address
does not match source ip filter for this rule.
Routing table decision: No matching routing rules: input address does not match
any routing rule source filters. Details: [Tried some rules but no matching]
No rules matched. Falling back to classic load balancing.
Classic load balance decision: Classic load balancing considered, but either the
policy was NONE or no target was available. Details: [NONE or invalid]

(1 row)

Enabling the default subcluster interior load balancing policy

Vertica attempts to apply the default subcluster interior load balancing policy if no other load balancing policy applies to an incoming connection and classic load balancing is not enabled. See Default Subcluster Interior Load Balancing Policy for a description of this rule.

To enable default subcluster interior load balancing, you must create network addresses for the nodes in a subcluster. Once you create the addresses, Vertica attempts to apply this rule to load balance connections within a subcluster when no other rules apply.

The following example confirms the database has no load balancing groups or rules. Then it adds publicly-accessible network addresses to the nodes in the primary subcluster. When these addresses are added, Vertica applies the default subcluster interior load balancing policy.

=> SELECT * FROM LOAD_BALANCE_GROUPS;
 name | policy | filter | type | object_name
------+--------+--------+------+-------------
(0 rows)

=> SELECT * FROM ROUTING_RULES;
 name | source_address | destination_name
------+----------------+------------------
(0 rows)

=> CREATE NETWORK ADDRESS node01_ext ON v_verticadb_node0001 WITH '203.0.113.1';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02_ext ON v_verticadb_node0002 WITH '203.0.113.2';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03_ext ON v_verticadb_node0003 WITH '203.0.113.3';
CREATE NETWORK ADDRESS

=> SELECT describe_load_balance_decision('11.0.0.100');
                                describe_load_balance_decision
-----------------------------------------------------------------------------------------------
Describing load balance decision for address [11.0.0.100] on subcluster [default_subcluster]
Load balance cache internal version id (node-local): [2]
Considered rule [auto_rr_default_subcluster] subcluster interior filter  [default_subcluster]...
current subcluster matches this rule
Matched to load balance group [auto_lbg_sc_default_subcluster] the group has policy
[ROUNDROBIN] number of addresses [3]
(0) LB Address: [203.0.113.1]:5433
(1) LB Address: [203.0.113.2]:5433
(2) LB Address: [203.0.113.3]:5433
Chose address at position [1]
Routing table decision: Success. Load balance redirect to: [203.0.113.2] port [5433]

(1 row)

Load balance both IPv4 and IPv6 connections

Connection load balancing policies regard IPv4 and IPv6 connections as separate networks. To load balance both types of incoming client connections, create two sets of network addresses, at least two load balancing groups, and two load balancing , once for each network address family.

This example creates two load balancing policies for the default subcluster: one for the IPv4 network addresses (192.168.111.31 to 192.168.111.33) and one for the IPv6 network addresses (fd9b:1fcc:1dc4:78d3::31 to fd9b:1fcc:1dc4:78d3::33).

=> SELECT node_name,node_address,subcluster_name FROM NODES;
      node_name       |  node_address  |  subcluster_name
----------------------+----------------+--------------------
 v_verticadb_node0001 | 192.168.111.31 | default_subcluster
 v_verticadb_node0002 | 192.168.111.32 | default_subcluster
 v_verticadb_node0003 | 192.168.111.33 | default_subcluster

=> CREATE NETWORK ADDRESS node01 ON v_verticadb_node0001 WITH
   '192.168.111.31';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node01_ipv6 ON v_verticadb_node0001 WITH
   'fd9b:1fcc:1dc4:78d3::31';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02 ON v_verticadb_node0002 WITH
   '192.168.111.32';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node02_ipv6 ON v_verticadb_node0002 WITH
   'fd9b:1fcc:1dc4:78d3::32';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03 ON v_verticadb_node0003 WITH
   '192.168.111.33';
CREATE NETWORK ADDRESS
=> CREATE NETWORK ADDRESS node03_ipv6 ON v_verticadb_node0003 WITH
   'fd9b:1fcc:1dc4:78d3::33';
CREATE NETWORK ADDRESS

=> CREATE LOAD BALANCE GROUP group_ipv4 WITH SUBCLUSTER default_subcluster
   FILTER '192.168.111.0/24';
CREATE LOAD BALANCE GROUP
=> CREATE LOAD BALANCE GROUP group_ipv6 WITH SUBCLUSTER default_subcluster
   FILTER 'fd9b:1fcc:1dc4:78d3::0/64';
CREATE LOAD BALANCE GROUP

=> CREATE ROUTING RULE all_ipv4 route '0.0.0.0/0' TO group_ipv4;
CREATE ROUTING RULE
=> CREATE ROUTING RULE all_ipv6 route '0::0/0' TO group_ipv6;
CREATE ROUTING RULE

=> SELECT describe_load_balance_decision('203.0.113.50');
                                                                                                                                                                                                                                                                                   describe_load_balance_decision
-----------------------------------------------------------------------------------------------
Describing load balance decision for address [203.0.113.50] on subcluster [default_subcluster]
Load balance cache internal version id (node-local): [3]
Considered rule [all_ipv4] source ip filter [0.0.0.0/0]... input address matches this rule
Matched to load balance group [ group_ipv4] the group has policy [ROUNDROBIN] number of addresses [3]
(0) LB Address: [192.168.111.31]:5433
(1) LB Address: [192.168.111.32]:5433
(2) LB Address: [192.168.111.33]:5433
Chose address at position [2]
Routing table decision: Success. Load balance redirect to: [192.168.111.33] port [5433]

(1 row)

=> SELECT describe_load_balance_decision('2001:0DB8:EA04:8F2C::1');
                                                                                                                                                                                                                                                                                                                                                                    describe_load_balance_decision
---------------------------------------------------------------------------------------------------------
Describing load balance decision for address [2001:0DB8:EA04:8F2C::1] on subcluster [default_subcluster]
Load balance cache internal version id (node-local): [3]
Considered rule [all_ipv4] source ip filter [0.0.0.0/0]... input address does not match source ip filter for this rule.
Considered rule [all_ipv6] source ip filter [0::0/0]... input address matches this rule
Matched to load balance group [ group_ipv6] the group has policy [ROUNDROBIN] number of addresses [3]
(0) LB Address: [fd9b:1fcc:1dc4:78d3::31]:5433
(1) LB Address: [fd9b:1fcc:1dc4:78d3::32]:5433
(2) LB Address: [fd9b:1fcc:1dc4:78d3::33]:5433
Chose address at position [2]
Routing table decision: Success. Load balance redirect to: [fd9b:1fcc:1dc4:78d3::33] port [5433]

(1 row)

Other examples

For other examples of using connection load balancing, see the following topics:

6 - Viewing load balancing policy configurations

Query the following system tables in the V_CATALOG Schema to see the load balance policies defined in your database:.

Query the following system tables in the V_CATALOG schema to see the load balance policies defined in your database:

NETWORK_ADDRESSES lists all of the network addresses defined in your database.
LOAD_BALANCE_GROUPS lists the contents of your load balance groups.

Note
This table does not directly lists all of your database's load balance groups. Instead, it lists the contents of the load balance groups. It is possible for your database to have load balancing groups that are not in this table because they do not contain any network addresses or fault groups.
ROUTING_RULES lists all of the routing rules defined in your database.

This example demonstrates querying each of the load balancing policy system tables.

=> \x
Expanded display is on.
=> SELECT * FROM V_CATALOG.NETWORK_ADDRESSES;
-[ RECORD 1 ]----+-----------------
name             | node01
node             | v_vmart_node0001
address          | 10.20.100.247
port             | 5433
address_family   | ipv4
is_enabled       | t
is_auto_detected | f
-[ RECORD 2 ]----+-----------------
name             | node02
node             | v_vmart_node0002
address          | 10.20.100.248
port             | 5433
address_family   | ipv4
is_enabled       | t
is_auto_detected | f
-[ RECORD 3 ]----+-----------------
name             | node03
node             | v_vmart_node0003
address          | 10.20.100.249
port             | 5433
address_family   | ipv4
is_enabled       | t
is_auto_detected | f
-[ RECORD 4 ]----+-----------------
name             | alt_node1
node             | v_vmart_node0001
address          | 192.168.1.200
port             | 8080
address_family   | ipv4
is_enabled       | t
is_auto_detected | f
-[ RECORD 5 ]----+-----------------
name             | test_addr
node             | v_vmart_node0001
address          | 192.168.1.100
port             | 4000
address_family   | ipv4
is_enabled       | t
is_auto_detected | f

=> SELECT * FROM LOAD_BALANCE_GROUPS;
-[ RECORD 1 ]----------------------
name        | group_all
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node01
-[ RECORD 2 ]----------------------
name        | group_all
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node02
-[ RECORD 3 ]----------------------
name        | group_all
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node03
-[ RECORD 4 ]----------------------
name        | group_1
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node01
-[ RECORD 5 ]----------------------
name        | group_1
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node02
-[ RECORD 6 ]----------------------
name        | group_2
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node01
-[ RECORD 7 ]----------------------
name        | group_2
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node02
-[ RECORD 8 ]----------------------
name        | group_2
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node03
-[ RECORD 9 ]----------------------
name        | etl_group
policy      | ROUNDROBIN
filter      |
type        | Network Address Group
object_name | node01

=> SELECT * FROM ROUTING_RULES;
-[ RECORD 1 ]----+-----------------
name             | internal_clients
source_address   | 192.168.1.0/24
destination_name | group_1
-[ RECORD 2 ]----+-----------------
name             | etl_rule
source_address   | 10.20.100.0/24
destination_name | etl_group
-[ RECORD 3 ]----+-----------------
name             | subnet_192
source_address   | 192.0.0.0/8
destination_name | group_all

7 - Maintaining load balancing policies

Once you have created load balancing policies, you maintain them using the following statements:.

Once you have created load balancing policies, you maintain them using the following statements:

ALTER NETWORK ADDRESS letsyou: rename, change the IP address, and enable or disable a network address.
ALTER LOAD BALANCE GROUP letsyou rename, add or remove network addresses or fault groups, change the fault group IP address filter, or change the policy of a load balance group.
ALTER ROUTING RULE letsyou rename, change the source IP address, and the target load balance group of a rule.

See the refence pages for these statements for examples.

Deleting load balancing policy objects

You can also delete existing load balance policy objects using the following statements:

Connection load balancing policies

Use cases

Using connection load balancing policies with IPv4 and IPv6

Default subcluster interior load balancing policy

Interior load balancing policy with multiple network addresses

Load balancing policies vs. classic load balancing

Steps to create a load balancing policy

See also

1 - Creating network addresses

Note

Note

Specifying a port number in a network address

2 - Creating connection load balance groups

Note

Creating load balancing groups from fault groups

Note

Creating load balance groups from subclusters

Setting the group's distribution policy

Note

The next step

3 - Creating load balancing routing rules

Creating a catch-all routing rule

4 - Testing connection load balancing policies

Note

5 - Load balancing policy examples

Enabling client connections from multiple networks

Isolating workloads

Enabling the default subcluster interior load balancing policy

Load balance both IPv4 and IPv6 connections

Other examples

6 - Viewing load balancing policy configurations

Note

7 - Maintaining load balancing policies

Deleting load balancing policy objects