#Row count limits — history

#Summary

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#v1 — f32 coordinates

Render positions (canvas coordinates, scroll_y, row_top) were f32.

f32 has 23 mantissa bits, representing integers exactly up to 2^24 = 16,777,216.

Beyond that, the epsilon grows:

Practical limit v1: ~300,000 rows.

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#v2 — usize indices, f64 coordinates

Coordinates moved to f64 (scroll precision is more than sufficient at this scale), but row indices remained usize.

On wasm32, usize is 32-bit, so usize::MAX = 4,294,967,295 (~4.3 billion). This ceiling was the bottleneck, not floating-point precision.

On x86-64, usize is 64-bit so there is no limit natively — but wasm32 code exceeded usize::MAX silently (overflow or panic depending on the build).

Practical limit v2: ~4.3 billion rows on wasm32.

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#v3 — u64 indices, f64 coordinates (2026-03-16)

Row indices (row_count, CellCoord.row, get_cell, row_top, visible_rows) moved from usize to u64. Column indices remain usize (never more than a few hundred).

The ceiling is no longer the index type but scroll_y: f64 precision. f64 has 52 mantissa bits, representing integers exactly up to 2^53.

#Concrete test (2026-03-16, row_height = 28)

Recommended maximum limit: 9_007_199_254_740_99_u64 (~9 x 10^14 rows).

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#Values in examples

• basic-web: 10_000_000_000_u64 (10 billion — comfortable)
• basic-leptos: 9_007_199_254_740_99_u64 (maximum tested limit)