This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: 热力图

| username: TiGod

[TiDB Usage Environment] Production Environment
[TiDB Version] v6.5.1
[Encountered Problem: Phenomenon and Impact] High memory consumption
[Resource Configuration] Go to TiDB Dashboard - Cluster Info - Hosts and take a screenshot of this page

Heatmap Information

Can the experts take a look at these images and see what issues they reflect? Are they normal?

| username: TiGod | Original post link

I found that TiDB has been consuming a lot of memory these past few days. I just doubled the memory, and the usage rate is almost at 90% again. I don’t know where the problem is.

| username: Billmay表妹 | Original post link

[TiDB Usage Environment] Production Environment / Testing / PoC
[TiDB Version]
[Reproduction Path] What operations were performed when the issue occurred
[Encountered Issue: Issue Phenomenon and Impact]
[Resource Configuration] Go to TiDB Dashboard - Cluster Info - Hosts and take a screenshot of this page
[Attachments: Screenshots / Logs / Monitoring]

Please post your issue according to the problem template~

| username: hey-hoho | Original post link

At least mention whether this is read traffic or write traffic (most likely read). Also, approximately how many bytes per minute is the yellow part?

Check the tables involved in the yellow part to see what SQL queries were executed. Are there any slow queries with large table scans? Pull out the execution plan and analyze it.

| username: TiGod | Original post link

Highlighted: 2.5G/min, dimmer: below 500M/min.

| username: TiGod | Original post link

Is it normal just to look at the distribution of brightness?

| username: redgame | Original post link

Can’t tell anything from the picture.

| username: Kongdom | Original post link

Physical memory of 15G? That’s a bit small, and it’s still mixed deployment.

| username: 春风十里 | Original post link

This picture is completely unclear. I think for mixed deployment, we first need to see how much memory each component occupies, such as how much memory TiDB and TiKV use, and then see which one uses more. Then we can analyze further.

| username: zhanggame1 | Original post link

The physical memory is too small, increase it to at least 64.

| username: TiGod | Original post link

We only have a tiny amount of data, and the backup is less than 1GB. Isn’t 4C16G for each of the three nodes enough? If we switch to MySQL, I think a single instance with 4C8G can handle it, right? Why does TiDB consume so many resources?

| username: 有猫万事足 | Original post link

If the problem can be solved by MySQL, there’s no need to use TiDB.

When resources are insufficient, PD should not be placed together with TiKV.
In a mixed deployment, if parameters are not adjusted, each component will assume it has exclusive use of the entire machine. Therefore, in a mixed deployment, parameters must be recalculated.

The parameters mentioned in the documentation need to be properly allocated, otherwise, it will be difficult to ensure cluster stability.

| username: Inkjade | Original post link

If resources are sufficient, it is recommended to deploy TiDB, TiKV, and PD independently. If you must perform a hybrid deployment, it is advisable to adjust the relevant parameters according to the documentation:

You need to allocate the parameters mentioned in the documentation properly; otherwise, it will be difficult to ensure cluster stability (e.g., OOM issues). This is because TiDB, PD, and TiKV will affect each other, leading to resource contention among the components.

| username: Kongdom | Original post link

The suitable scenario is different, so you still need to choose the appropriate database based on your own business, data volume, and development.

| username: BraveChen | Original post link

Based on my years of experience, this is most likely due to a missing index on a table or an invalid index, leading to frequent full table scans and causing table-level hotspots. You should check for slow SQL in this case.

| username: cy6301567 | Original post link

We are the same, gradually upgraded.

| username: system | Original post link

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