replace mirror node

General Discussions - English
1

how to replace a mirror node in Manticore Search without restarting the service?

2

No way atm. We have in plans to simplify this.

The docs for now is Manticore Search Manual: Creating a cluster > Setting up replication > Managing replication nodes

3

So, if I have a distributed table and I’ve configured agent mirrors like this: agent=node1|node2:9312:shard1 and node2 goes down, I need to replace it with another node, I would need to modify the configuration and then restart the service.
thx.

4

Oh, you mean not a replication node by “mirror node”, but just a remote agent. Then here’s what you can do:

RT mode:

Let’s assume we have a distributed table like this one:

➜  ~ mysql -P9306 -h0 -v -e "drop table if exists t; create table t; drop table if exists dist; create table dist type='distributed' agent='127.0.0.1:9312:t|127.0.0.1:9312:t'; desc dist;"
--------------
drop table if exists t
--------------

--------------
create table t
--------------

--------------
drop table if exists dist
--------------

--------------
create table dist type='distributed' agent='127.0.0.1:9312:t|127.0.0.1:9312:t'
--------------

--------------
desc dist
--------------

+------------------+-------------------+
| Agent            | Type              |
+------------------+-------------------+
| 127.0.0.1:9312:t | remote_1_mirror_1 |
| 127.0.0.1:9312:t | remote_1_mirror_2 |
+------------------+-------------------+

To update it, we need to remove it and create a new one:

➜  ~ time mysql -P9306 -h0 -v -e "drop table dist; create table dist type='distributed' agent='127.0.0.1:9312:t'; desc dist;"
--------------
drop table dist
--------------

--------------
create table dist type='distributed' agent='127.0.0.1:9312:t'
--------------

--------------
desc dist
--------------

+------------------+----------+
| Agent            | Type     |
+------------------+----------+
| 127.0.0.1:9312:t | remote_1 |
+------------------+----------+
mysql -P9306 -h0 -v -e   0.01s user 0.01s system 39% cpu 0.033 total

You will experience a short downtime: about 30ms in my case.

Plain mode

Let’s assume we have this config:

➜  ~ cat min_dist.conf
searchd {
    listen = 9316
    listen = 9315:mysql41
    log = searchd.log
    pid_file = searchd.pid
    binlog_path =
}

source src {
    type = csvpipe
    csvpipe_command = echo "1,abc"
    csvpipe_field = f
}

index idx {
    type = plain
    source = src
    path = idx
}

index dist {
    type = distributed
    agent = 127.0.0.1:9312:t|127.0.0.1:9312:t
}

2 agents in the dist table:

➜  ~ mysql -P9315 -h0 -e "desc dist"
+------------------+-------------------+
| Agent            | Type              |
+------------------+-------------------+
| 127.0.0.1:9312:t | remote_1_mirror_1 |
| 127.0.0.1:9312:t | remote_1_mirror_2 |
+------------------+-------------------+

To update the distributed table let’s change the config like this:

-    agent = 127.0.0.1:9312:t|127.0.0.1:9312:t
+    agent = 127.0.0.1:9312:t

and run RELOAD TABLES:

➜  ~ mysql -P9315 -h0 -e "reload tables"
➜  ~ mysql -P9315 -h0 -e "desc dist"
+------------------+----------+
| Agent            | Type     |
+------------------+----------+
| 127.0.0.1:9312:t | remote_1 |
+------------------+----------+

As we can see, now there’s only one node left.

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