Setting up replication

With Manticore, write transactions (such as INSERT, REPLACE, DELETE, TRUNCATE, UPDATE, COMMIT) can be replicated to other cluster nodes before the transaction is fully applied on the current node. Currently, replication is supported for percolate and rt tables in Linux and macOS. However, Manticore Search packages for Windows do not provide replication support.

Manticore’s replication is powered by the Galera library and boasts several impressive features:

• True Multi-Master: Read and write to any node at any time.
• virtually synchronous replication No slave lag and no data loss after a node crash.
• Hot Standby: No downtime during failover (since there is no failover).
• Tightly Coupled: All nodes hold the same state and no diverged data between nodes is allowed.
• Automatic Node Provisioning: No need to manually backup the database and restore it on a new node.
• Easy to Use and Deploy.
• Detection and Automatic Eviction of Unreliable Nodes.
• Certification-based Replication.

To set up replication in Manticore Search:

• The data_dir option must be set in the “searchd” section of the configuration file. Replication is not supported in plain mode.
• A listen directive must be specified, containing an IP address accessible by other nodes, or a node_address with an accessible IP address.
• Optionally, you can set unique values for server_id on each cluster node. If no value is set, the node will attempt to use the MAC address or a random number to generate the server_id.

If there is no replication listen directive set, Manticore will use the first two free ports in the range of 200 ports after the default protocol listening port for each created cluster. To set replication ports manually, the listen directive (of replication type) port range must be defined and the address/port range pairs must not intersect between different nodes on the same server. As a rule of thumb, the port range should specify at least two ports per cluster.

Replication cluster

A replication cluster is a group of nodes in which a write transaction is replicated. Replication is set up on a per-table basis, meaning that one table can only belong to one cluster. There is no limit on the number of tables that a cluster can have. All transactions such as INSERT, REPLACE, DELETE, TRUNCATE on any percolate or real-time table that belongs to a cluster are replicated to all the other nodes in that cluster. Replication is multi-master, so writes to any node or multiple nodes simultaneously will work just as well.

To create a cluster, you can typically use the command create cluster with CREATE CLUSTER <cluster name>, and to join a cluster, you can use join cluster with JOIN CLUSTER <cluster name> at 'host:port'. However, in some rare cases, you may want to fine-tune the behavior of CREATE/JOIN CLUSTER. The available options are:

name

This option specifies the name of the cluster. It should be unique among all the clusters in the system.

path

The path option specifies the data directory for write-set cache replication and incoming tables from other nodes. This value should be unique among all the clusters in the system and should be specified as a relative path to the data_dir. directory. By default, it is set to the value of data_dir.

nodes

The nodes option is a list of address:port pairs for all the nodes in the cluster, separated by commas. This list should be obtained using the node’s API interface and can include the address of the current node as well. It is used to join the node to the cluster and to rejoin it after a restart.

options

The options option allows you to pass additional options directly to the Galera replication plugin, as described in the Galera Documentation Parameters

Write statements

When working with a replication cluster, all write statements such as INSERT, REPLACE, DELETE, TRUNCATE, UPDATE that modify the content of a cluster’s table must use thecluster_name:index_name expression instead of the table name. This ensures that the changes are propagated to all replicas in the cluster. If the correct expression is not used, an error will be triggered.

In the HTTP interface, the cluster property must be set along with the table name for all write statements to a cluster’s table. Failure to set the cluster property will result in an error.

The Auto ID for a table in a cluster should be valid as long as the server_id is correctly configured.

SQL:

INSERT INTO posts:weekly_index VALUES ( 'iphone case' )
TRUNCATE RTINDEX click_query:weekly_index
UPDATE INTO posts:rt_tags SET tags=(101, 302, 304) WHERE MATCH ('use') AND id IN (1,101,201)
DELETE FROM clicks:rt WHERE MATCH ('dumy') AND gid>206

POST /insert -d '
{
  "cluster":"posts",
  "index":"weekly_index",
  "doc":
  {
    "title" : "iphone case",
    "price" : 19.85
  }
}'
POST /delete -d '
{
  "cluster":"posts",
  "index": "weekly_index",
  "id":1
}'

$index->addDocuments([
        1, ['title' => 'iphone case', 'price' => 19.85]
]);
$index->deleteDocument(1);

Python:

indexApi.insert({"cluster":"posts","index":"weekly_index","doc":{"title":"iphone case","price":19.85}})
indexApi.delete({"cluster":"posts","index":"weekly_index","id":1})

Javascript:

res = await indexApi.insert({"cluster":"posts","index":"weekly_index","doc":{"title":"iphone case","price":19.85}});
 res = await indexApi.delete({"cluster":"posts","index":"weekly_index","id":1});

java:

InsertDocumentRequest newdoc = new InsertDocumentRequest();
HashMap<String,Object> doc = new HashMap<String,Object>(){{
    put("title","Crossbody Bag with Tassel");
    put("price",19.85);
}};
newdoc.index("weekly_index").cluster("posts").id(1L).setDoc(doc);
sqlresult = indexApi.insert(newdoc);

DeleteDocumentRequest deleteRequest = new DeleteDocumentRequest();
deleteRequest.index("weekly_index").cluster("posts").setId(1L);
indexApi.delete(deleteRequest);

Read statements

Read statements such as SELECT, CALL PQ, DESCRIBE can either use regular table names that are not prepended with a cluster name, or they can use the cluster_name:index_nameformat. If the latter is used, the cluster_name component is ignored.

When using the HTTP endpoint json/search, the cluster property can be specified if desired, but it can also be omitted.

SQL:

SELECT * FROM weekly_index
CALL PQ('posts:weekly_index', 'document is here')

POST /search -d '
{
  "cluster":"posts",
  "index":"weekly_index",
  "query":{"match":{"title":"keyword"}}
}'
POST /search -d '
{
  "index":"weekly_index",
  "query":{"match":{"title":"keyword"}}
}'

Cluster parameters

Replication plugin options can be adjusted using the SET statement.

A list of available options can be found in the Galera Documentation Parameters .

SQL:

SET CLUSTER click_query GLOBAL 'pc.bootstrap' = 1

POST /cli -d "
SET CLUSTER click_query GLOBAL 'pc.bootstrap' = 1
"

Cluster with diverged nodes

It’s possible for replicated nodes to diverge from one another, leading to a state where all nodes are labeled as non-primary. This can occur as a result of a network split between nodes, a cluster crash, or if the replication plugin experiences an exception when determining the primary component. In such a scenario, it’s necessary to select a node and promote it to the role of primary component.

To identify the node that needs to be promoted, you should compare the last_committed cluster status variable value on all nodes. If all the servers are currently running, there’s no need to restart the cluster. Instead, you can simply promote the node with the highest last_committed value to the primary component using the SET statement (as demonstrated in the example).

The other nodes will then reconnect to the primary component and resynchronize their data based on this node.

SQL:

SET CLUSTER posts GLOBAL 'pc.bootstrap' = 1

POST /cli -d "
SET CLUSTER posts GLOBAL 'pc.bootstrap' = 1
"

Replication and cluster

To use replication, you need to define one listen port for SphinxAPI protocol and one listen for replication address and port range in the configuration file. Also, specify the data_dir folder to receive incoming tables.

ini:

searchd {
  listen   = 9312
  listen   = 192.168.1.101:9360-9370:replication
  data_dir = /var/lib/manticore/
  ...
 }

To replicate tables, you must create a cluster on the server that has the local tables to be replicated.

SQL:

CREATE CLUSTER posts

POST /cli -d "
CREATE CLUSTER posts
"

$params = [
    'cluster' => 'posts'
    ]
];
$response = $client->cluster()->create($params);

Python:

utilsApi.sql('CREATE CLUSTER posts')

Javascript:

res = await utilsApi.sql('CREATE CLUSTER posts');

Java:

utilsApi.sql("CREATE CLUSTER posts");

Add these local tables to the cluster

SQL:

ALTER CLUSTER posts ADD pq_title
ALTER CLUSTER posts ADD pq_clicks

POST /cli -d "
ALTER CLUSTER posts ADD pq_title
"
POST /cli -d "
ALTER CLUSTER posts ADD pq_clicks
"

$params = [
  'cluster' => 'posts',
  'body' => [
     'operation' => 'add',
     'index' => 'pq_title'

  ]
];
$response = $client->cluster()->alter($params);
$params = [
  'cluster' => 'posts',
  'body' => [
     'operation' => 'add',
     'index' => 'pq_clicks'

  ]
];
$response = $client->cluster()->alter($params);   

Python:

utilsApi.sql('ALTER CLUSTER posts ADD pq_title')
utilsApi.sql('ALTER CLUSTER posts ADD pq_clicks')

Javascript:

res = await utilsApi.sql('ALTER CLUSTER posts ADD pq_title');
res = await utilsApi.sql('ALTER CLUSTER posts ADD pq_clicks');

Java:

utilsApi.sql("ALTER CLUSTER posts ADD pq_title");
utilsApi.sql("ALTER CLUSTER posts ADD pq_clicks");

All other nodes that wish to receive a replica of the cluster’s tables should join the cluster as follows:

SQL:

JOIN CLUSTER posts AT '192.168.1.101:9312'

POST /cli -d "
JOIN CLUSTER posts AT '192.168.1.101:9312'
"

$params = [
  'cluster' => 'posts',
  'body' => [
      '192.168.1.101:9312'
  ]
];
$response = $client->cluster->join($params);

Python:

utilsApi.sql('JOIN CLUSTER posts AT \'192.168.1.101:9312\'')

Javascript:

res = await utilsApi.sql('JOIN CLUSTER posts AT \'192.168.1.101:9312\'');

Java:

utilsApi.sql("JOIN CLUSTER posts AT '192.168.1.101:9312'");

When running queries, prepend the table name with the cluster name posts: or use the cluster property for HTTP request object.

SQL:

INSERT INTO posts:pq_title VALUES ( 3, 'test me' )

POST /insert -d '
{
  "cluster":"posts",
  "index":"pq_title",
  "id": 3
  "doc":
  {
    "title" : "test me"
  }
}'

$index->addDocuments([
        3, ['title' => 'test me']
]);

Python:

indexApi.insert({"cluster":"posts","index":"pq_title","id":3"doc":{"title":"test me"}})

Javascript:

res = await indexApi.insert({"cluster":"posts","index":"pq_title","id":3"doc":{"title":"test me"}});

java:

InsertDocumentRequest newdoc = new InsertDocumentRequest();
HashMap<String,Object> doc = new HashMap<String,Object>(){{
    put("title","test me");
}};
newdoc.index("pq_title").cluster("posts").id(3L).setDoc(doc);
sqlresult = indexApi.insert(newdoc);

All queries that modify tables in the cluster are now replicated to all nodes in the cluster.