*: add column-level masking policy feature document

[tiancaiamao]

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• This PR is translated from: *: add document for column-level masking policy feature docs#22613
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[qiancai]

@tiancaiamao Please involve a tech reviewer for this PR. Thanks.

[bb7133]

Please address the comments~

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[qiancai]

Rest LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-06-08 08:06:35.181916609 +0000 UTC m=+774496.252233989: ☑️ agreed by qiancai.

[qiancai]

TBD.

[qiancai]

这里要加一个 bullet，写数值类型吗？

[tiancaiamao]

不支持数值类型

支持这些:

• VARCHAR, CHAR, TEXT(TINYTEXT, MEDIUMTEXT, LONGTEXT), BLOB(TINYBLOB, MEDIUMBLOB, LONGBLOB)
  • For the LONGTEXT and BLOB types, full masking (full redaction) or NULL masking needs to be supported.
• DATE, TIME,DATETIME,TIMESTAMP,YEAR

[tiancaiamao]

PTAL @bb7133

[expxiaoli]

LGTM

[ti-chi-bot]

@expxiaoli: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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[tiancaiamao]

/retest

[qiancai]

hold this PR because the related code is not fully ready according to @tiancaiamao

[ti-chi-bot]

@tiancaiamao: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-verify	ab3e458	link	true	/test pull-verify

Full PR test history. Your PR dashboard.

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