Add more description about SHARD_ROW_ID_BITS (#21467) #21598
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Co-authored-by: Aolin <[email protected]>
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Summary of Changes
Hello @ti-chi-bot, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request enhances the TiDB documentation by providing more comprehensive details and best practices for configuring SHARD_ROW_ID_BITS. The updates aim to improve user understanding of how this setting impacts _tidb_rowid structure, auto-increment behavior, and overall hotspot mitigation, offering clearer guidance on balancing performance and resource utilization.
Highlights
- _tidb_rowid Structure: The documentation now includes a detailed breakdown of the
_tidb_rowidstructure whenSHARD_ROW_ID_BITSis configured, illustrating how the 64 bits are divided into sign, shard, and auto-increment components. - Auto-increment Bit Behavior: New content clarifies the behavior when auto-increment bits are exhausted, leading to
Failed to read auto-increment value from storage engineerrors, and specifies the maximum value range for_tidb_rowid. - Shard Bit vs. Auto-increment Bit Balance: The updated guide explains the critical balance between increasing shard bits (for better randomness) and decreasing auto-increment bits (reducing available space), advising users to consider this trade-off.
- Optimal Shard Bit Configuration: A new best practice recommends setting
SHARD_ROW_ID_BITSbased on the logarithm (base 2) of the number of TiKV nodes, ensuring optimal load distribution across the cluster.
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Code Review
This pull request adds a detailed explanation of SHARD_ROW_ID_BITS, including its bit structure and best practices for configuration. The added information is valuable for users looking to mitigate write hotspots. I've provided a few suggestions to improve the clarity and conciseness of the new documentation, making it easier for users to understand and apply the concepts.
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/approve |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: qiancai The full list of commands accepted by this bot can be found here. The pull request process is described here
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Approvers can indicate their approval by writing |
This is an automated cherry-pick of #21467
What is changed, added or deleted? (Required)
Add notice about setting the value of SHARD_ROW_ID_BITS
Which TiDB version(s) do your changes apply to? (Required)
Tips for choosing the affected version(s):
By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.
For details, see tips for choosing the affected versions (in Chinese).
What is the related PR or file link(s)?
Do your changes match any of the following descriptions?