In the HoloWeb console, you can use the resharding feature to quickly reshard a table from a table group to another table group and quickly perform troubleshooting if an issue occurs. This topic describes how to perform table resharding in the HoloWeb console. For more information about the principles of table group, shard count, and resharding, see Basic concepts.
Limits
Hologres V2.0.24 and later support table resharding in the HoloWeb console. If the version of your Hologres instance is earlier than V2.0.24, upgrade your instance or perform table resharding by following the instructions in Use the resharding feature to migrate tables to a new table group in the "User guide of table groups and shard counts" topic.
For more information about other limits of using the resharding feature, see Use the resharding feature to migrate tables to a new table group in the "User guide of table groups and shard counts" topic.
Create a table resharding task
Go to the HoloWeb console. For more information, see Connect to HoloWeb.
In the HoloWeb console, click Data Solution in the top navigation bar.
On the Data Solution page, click Table Resharding in the left-side navigation pane.
On the Table Resharding page, click Create Table Resharding Task. Then, configure parameters described in the following table. For parameters that are not described in the following table, retain their default values.
Section
Parameter
Description
Instance
Instance Name
The name of the desired Hologres instance.
Database
The database in the Hologres instance.
Table Information
Schema
The schema in which the table to be resharded resides.
Table
The table that you want to reshard.
New Table Group
The table group to which you want to reshard the table.
Configure GUC Parameters for Data Import
GUC Parameters
Optional. Resharding involves data import. If the memory overhead is excessive, the settings of specific GUC parameters may need to be modified. For more information, see What can I do if an OOM error is reported during data import or export? in the "FAQ about OOM" topic.
Click Submit. You can view the information about resharding tasks on the Table Resharding page.
NoteProgress: If you reshard a partitioned table, this column displays the percentage of child tables on which resharding is complete. If you reshard a non-partitioned table, this column displays the progress only as 0% or 100%.
Check the task status. If Successful is displayed in the Status column, the resharding task is complete.
Troubleshooting
During table resharding, the table is configured as read-only and then resharded to the new table group by using a temporary table. Resharding tasks involve data import and are time-consuming. During the resharding process, exceptions such as out of memory (OOM) and manual termination of tasks may occur. In this case, Status is displayed as Interrupted or Failed. If the exceptions occur, the original table is still in the read-only state, and a temporary table named in the <initial_table_name>_xxxxxxxx format is generated in the database. You can perform one of the following operations:
Continue to run the task.
If the resharding task is interrupted due to a misoperation, or the resharding task fails due to errors such as OOM and the GUC parameter adjustment is complete, you can click Continue to Run in the Operation column. The background resumes the resharding task from the interrupted progress.
Cancel the task.
If you want to restore the table to its initial status, click Cancel Task in the Operation column. The background restores the table to the initial status by performing operations such as disabling the read-only state and clearing the temporary table.