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dumpling: update -r option string key implementation doc #21324

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Aug 1, 2025
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dumpling: update -r option string key implementation doc #21324

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dumpling: update -r option string key implementation doc
takaidohigasi Jul 3, 2025
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Update dumpling-overview.md
takaidohigasi Jul 4, 2025
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Update dumpling-overview.md
hfxsd Jul 31, 2025
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hfxsd Jul 31, 2025
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6 changes: 5 additions & 1 deletion dumpling-overview.md
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Expand Up @@ -95,7 +95,11 @@ In the command above:
+ The `-h`, `-P`, and `-u` option respectively mean the address, the port, and the user. If a password is required for authentication, you can use `-p $YOUR_SECRET_PASSWORD` to pass the password to Dumpling.
+ The `-o` (or `--output`) option specifies the export directory of the storage, which supports an absolute local file path or an [external storage URI](/external-storage-uri.md).
+ The `-t` option specifies the number of threads for the export. Increasing the number of threads improves the concurrency of Dumpling and the export speed, and also increases the database's memory consumption. Therefore, it is not recommended to set the number too large. Usually, it's less than 64.
+ The `-r` option enables the in-table concurrency to speed up the export. The default value is `0`, which means disabled. A value greater than 0 means it is enabled, and the value is of `INT` type. When the source database is TiDB, a `-r` value greater than 0 indicates that the TiDB region information is used for splitting, and reduces the memory usage. The specific `-r` value does not affect the split algorithm. When the source database is MySQL and the primary key or the first column of the composite primary key is of the `INT` type, specifying `-r` can also enable the in-table concurrency.
+ The `-r` option enables in-table concurrency to speed up the export. It is disabled by default (value `0`). When enabled with a value greater than `0`, the behavior depends on the source database.

- For TiDB, Dumpling uses region information for splitting, which also reduces memory usage. The specified `-r` value does not affect the split algorithm.
- For MySQL, this option is supported when the primary key (or the first column of a composite primary key) is of an `INT` or `STRING` type.

+ The `-F` option is used to specify the maximum size of a single file (the unit here is `MiB`; inputs like `5GiB` or `8KB` are also acceptable). It is recommended to keep its value to 256 MiB or less if you plan to use TiDB Lightning to load this file into a TiDB instance.

> **Note:**
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