Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Update the limitations of schema-cache #19819

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Update the limitations of schema-cache #19819

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions schema-cache.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,9 @@ You can enable the schema caching feature by configuring the system variable [`t

In scenarios with a large number of databases and tables, the following known issues exist:

- The number of tables in a single cluster cannot exceed 3 million.
- When the number of tables in a single cluster exceeds 300,000, do not set the value of [`tidb_schema_cache_size`](/system-variables.md#tidb_schema_cache_size-new-in-v800) to 0, as it may cause TiDB to run out of memory (OOM).
- When using foreign keys, the execution time of DDL operations in the cluster may increase.
- When the tables are irregularly accessed, such as one set of tables are accessed at time1 while another set are accessed at time2, and the value of `tidb_schema_cache_size` is small, the schema information might be frequently evicted and cached, leading to performance fluctuations. This feature is more suitable for scenarios where frequently accessed databases and tables are relatively fixed.
- Statistics information might not be collected in a timely manner.
- Access to some metadata information might become slower.
Expand Down
Loading