Change 1 — Columnar Snapshot Internal:
- Add ColumnSnapshot struct (type + str_ids/i64/f64 per column) in data_table_internal.h
- Add SnapshotCache struct with pointer-identity sentinel (last_cells_ptr)
- Add SnapshotCache field to UiState singleton
- In render(): rebuild snapshot after join materialization when cells ptr changes
Uses same pointer-identity pattern as existing stats_last_cells in State
Int/Float columns parsed once via parse_number; String/Auto interned
Change 2 — String Interning:
- Add StringPool struct (strings + unordered_map<string_view, uint32_t>) to data_table_types.h
- StringPool is per-State (NOT global) for table isolation
- intern(sv) inserts if absent, returns stable uint32_t index
- Cleared + rebuilt on each snapshot rebuild for index coherence
- Add string_pool field to State struct
Documentation:
- Extended header comment in data_table_internal.h describing design,
StringPool API, invariants (pointer-identity, row→snapshot_row),
and how stats_last_cells and snapshot coexist independently
Build: fn_module_data_table + tables_qa pass, no new errors (only
pre-existing -Wformat-truncation warnings unrelated to this change).
Public API (data_table.h, TableInput, render() signature) unchanged.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
egutierrez
ce7470d5f5