Add a read-only In-Memory Columnar Index (IMCI) node to your PolarDB for MySQL cluster to accelerate analytical queries without affecting your existing row-store workloads.
Prerequisites
Before you begin, make sure your cluster meets the following requirements.
Version requirements
Your cluster must meet the minimum revision version based on its edition and MySQL version:
| Edition | MySQL version | Minimum revision version |
|---|---|---|
| Enterprise Edition | 8.0.1 | 8.0.1.1.22 |
| Enterprise Edition | 8.0.2 | 8.0.2.2.12 |
| Standard Edition (X86) | 8.0.1 | 8.0.1.1.38 |
| Standard Edition (X86) | 8.0.2 | 8.0.2.2.19 |
Cluster requirements
The cluster has at least one existing read-only node. Single-node clusters do not support read-only IMCI nodes.
Usage notes
Multi-master clusters
For a Multi-master Cluster (Limitless) cluster, set the cluster parameter loose_polar_enable_imci_with_mm to ON before adding a global read-only IMCI node.
Global Database Network clusters
For a cluster in a global database network (GDN), enable the loose_polar_enable_imci_with_standby cluster parameter before adding a read-only IMCI node. The cluster must also meet one of these version requirements:
MySQL 8.0.1 with revision version 8.0.1.1.48 or later
MySQL 8.0.2 with revision version 8.0.2.2.27 or later
Columnar statement fallback
When a columnar statement hits a usage limitation, the system automatically falls back to row-store execution.
Compatibility with failover with hot replica
IMCI and failover with hot replica compatibility depends on your revision version:
| Revision version | Can use IMCI with hot replica? | Notes |
|---|---|---|
| 8.0.1.1.43 or later, or 8.0.2.2.24 or later | Yes | No restrictions |
| 8.0.1.1.42 or 8.0.2.2.23 | Partial | If the cluster has a hot replica node, you can add IMCI nodes. If an IMCI node already exists, you cannot enable hot standby on any read-only node. |
| Earlier than 8.0.1.1.42 or earlier than 8.0.2.2.23 | No | If hot replica is enabled, you cannot add IMCI nodes. If an IMCI node already exists, you cannot enable hot standby on any read-only node. |
To add an IMCI node on a cluster where hot replica is enabled and the revision version is earlier than 8.0.1.1.42 or 8.0.2.2.23, contact Alibaba Cloud to disable the Voting Disk module of the failover with hot replica feature. All nodes in the cluster restart automatically when Voting Disk is being disabled.
Procedure
Add a read-only IMCI node from the console
Log on to the PolarDB console. In the upper-left corner, select the region where your cluster resides.
Open the Add/Remove Node dialog box using one of these methods:
On the Clusters page, click Actions in the Add/Remove Node column.
On the Basic Information page of the cluster, click Add/Remove Node in the Database Nodes section.
Select Add Read-only IMCI Node and click OK.
Configure the node:
Click +Add an IMCI Node.
Select the node specifications.
Set the Switching Time parameter.
(Optional) Review the Terms of Service and Service Level Agreement.
Click Buy Now and complete the payment.
After the payment is complete, go to the cluster details page and wait for the node to enter the Running state. In the Database Nodes section, Read-only IMCI Node is the new column-store node, and Read-only Node is the original row-store node.
Add a read-only IMCI node during purchase
On the PolarDB purchase page, find the Nodes parameter and set Read-only IMCI Nodes to the number of nodes you want.
After the purchase is complete, verify the node was added as described in the next section.
Verify the result
Log on to the PolarDB console and go to the Basic Information page of your cluster. In the Database Nodes section, confirm that the read-only IMCI node appears and its status is Running.
API reference
| API | Description |
|---|---|
| CreateDBNodes | Adds a read-only node to a PolarDB cluster |