Add FORMAT_BYTES and FORMAT_NANO_TIME functions

[dveeden]

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• v9.0 (TiDB 9.0 versions)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
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[gemini-code-assist]

Hello @dveeden, 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!

Summary of Changes

This pull request adds two new utility functions to TiDB: FORMAT_BYTES() and FORMAT_NANO_TIME(). These functions format a number of bytes and nanoseconds, respectively, into human-readable strings. The changes include adding the new functions to the functions-and-operators/utility-functions.md documentation file, as well as updating the table of contents in TOC.md and TOC-tidb-cloud.md to include a link to the new utility functions documentation.

Highlights

• New Functions: Introduces FORMAT_BYTES() to format byte sizes into human-readable strings (e.g., '10.00 MiB').
• New Functions: Introduces FORMAT_NANO_TIME() to format nanosecond values into human-readable strings (e.g., '1.00 ms').
• Documentation: Adds a new utility-functions.md file under functions-and-operators/ to document the new functions.
• Table of Contents: Updates TOC.md and TOC-tidb-cloud.md to include a link to the new Utility Functions documentation.

Changelog

• TOC-tidb-cloud.md
  • Added 'Utility Functions' to the table of contents, linking to the new documentation page.
• TOC.md
  • Added 'Utility Functions' to the table of contents, linking to the new documentation page.
• functions-and-operators/utility-functions.md
  • Created a new documentation page for 'Utility Functions'.
  • Documented the FORMAT_BYTES() function with a description and example.
  • Documented the FORMAT_NANO_TIME() function with a description and example.

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[gemini-code-assist]

Code Review

This pull request adds two new utility functions, FORMAT_BYTES and FORMAT_NANO_TIME, to TiDB's documentation. The changes include adding the function documentation and updating the table of contents. Overall, the changes are well-structured and clear.

Merge Readiness

The pull request is well-structured and clear, and the changes seem straightforward. I recommend merging it after addressing the minor suggestions in the review comments. I am unable to approve this pull request, and that users should have others review and approve this code before merging.

[dveeden]

Checking the docs against TiDB v8.5.1:

dvaneeden@dve-carbon:~/dev/pingcap/docs/functions-and-operators$ for bi in $(mysql --host 127.0.0.1 --port 4000 -u root -BNe 'show builtins'); do n=$(git grep -li $bi | wc -l); [ $n == 0 ] && echo $bi; done
bitand
bitneg
bitor
bitxor
char_func
default_func
des_decrypt
des_encrypt
format_bytes
format_nano_time
getparam
insert_func
intdiv
isfalse
istrue
json_memberof
leftshift
master_pos_wait
nulleq
old_password
password_func
rightshift
setvar
unaryminus
vec_as_text
vec_cosine_distance
vec_dims
vec_from_text
vec_l1_distance
vec_l2_distance
vec_l2_norm
vec_negative_inner_product

1. Vector search related things are in ../vector-search/vector-search-functions-and-operators.md. Those are false positives.
2. Things like bitand are names for operators. Those are also false positives.
3. password_func should not be in the output, that's an issue, but not on the docs side.
4. DES functions are deprecated/removed
5. OLD_PASSWORD() is deprected/removed
6. MASTER_POS_WAIT() is not implemented, It always returns an error.

So this is a list of things to check:

char_func               - Not intended as function?
default_func            - Not a real function?
format_bytes            - Should be in the docs, This PR
format_nano_time        - Should be in the docs, This PR
getparam                - Prepared statements related?
insert_func             - Not intended as real function?
isfalse                 - Not intended as real function?
istrue                  - Not intended as real function?
json_memberof           - Should be documented?
setvar                  - Unknown

[dveeden]

Related: pingcap/tidb#60906

Looks like JSON_MEMBEROF might be related to MEMBER OF (e.g. SELECT 2 MEMBER OF (JSON_ARRAY(1,2,3)) )

[dveeden]

Also related: pingcap/tidb#60928

[mjonss]

LGTM

[ti-chi-bot]

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In response to this:

LGTM

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[qiancai]

Rest LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-06-16 08:35:39.480354497 +0000 UTC m=+87992.203533480: ☑️ agreed by hfxsd.
• 2025-06-16 09:18:09.853771251 +0000 UTC m=+90542.576950228: ☑️ agreed by qiancai.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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Needs approval from an approver in each of these files:

• OWNERS [hfxsd]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #21191.
But this PR has conflicts, please resolve them!

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #21192.