Angle brackets < > in field values are missing, and enabling RENDER COLUMNS IN HTML FORMAT slows down Superset

[SukiSeven]

I found two related issues in Superset when working with MySQL data:

1.Field values with angle brackets are missing

• • In MySQL the value is:
    (HOFO,6hd, 6.0)
• • But in Superset it only shows:
    (HOFO,6hd, 6.0)

This happens at row 144 — the and parts are missing there. The problem is inconsistent: some <...> fragments are preserved, others are hidden.

The text inside < > is missing (not all brackets are dropped, but some).
I have already enabled RENDER COLUMNS IN HTML FORMAT, but the issue still happens.
Expected: Superset should display the text exactly as stored in MySQL, including < >.

2.Performance issue after enabling HTML rendering
Previously, Superset did not have the RENDER COLUMNS IN HTML FORMAT option.
Our DevOps team added this feature by editing .tsx files and rebuilding the image.
After rebuilding, Superset became noticeably slower when rendering tables.
Why would enabling this option and rebuilding cause such performance degradation?

@dosu

[dosubot[bot]]

Superset interprets angle brackets (< >) in field values as HTML tags, which causes the text inside them to be hidden or removed when HTML rendering is enabled. To display the full value—including angle brackets—disable the "Render Columns in HTML Format" option in table settings and the "Render HTML" option in SQL Lab settings. This will show your data as plain text without stripping out the brackets [source].

Performance degradation after enabling HTML rendering is likely due to extra processing for parsing and sanitizing HTML content in each table cell. Rendering raw HTML can be much more expensive than plain text, especially if the implementation disables table virtualization or uses more complex cell renderers, leading to slower table rendering [source].

If you need to display angle brackets as literal text, it's best to keep HTML rendering off and let Superset treat all values as plain text. If you must enable HTML rendering, consider reviewing your sanitizer logic to ensure it doesn't strip out non-HTML content and optimize your cell rendering to avoid unnecessary overhead.

To reply, just mention @dosu.

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