Changes for version 0.002.0 - 2026-09-11
- Enhancements
- Add collision_prefix constructor parameter (HashRef[Str], keyed by zero-based database index). When a secondary database has a column that collides with an existing column in the merged view, the secondary column is published as "$prefix.$col" so both values survive in every merged row. Omitting collision_prefix preserves the previous last-database-wins behaviour unchanged. Criteria on prefixed column names are correctly translated back to the database's own column name before the query is issued. The join_column is never prefixed.
- Add t/collision-prefix.t: 12 subtests covering columns(), schema(), row merge, criteria routing by prefixed name, fetchrow_hashref, backward compat, index-0 ignore, non-colliding pass-through, remove_column, three-database chaining, and add_database.
- Add t/xlsx.t: end-to-end tests with XLSX-backed component databases (requires DBD::Excel + Spreadsheet::WriteExcel; skipped otherwise). Exercises left/inner/outer join, criteria routing, fetchrow_hashref, columns(), collision_prefix, and add_database against real .xlsx files. Documents that DBD::Excel returns empty schema() for XLSX databases.
- Hoist per-secondary-database constants (local join-column name, rename flag, rename map) outside the O(K*N*R) key/row/column merge loop, eliminating repeated hash lookups on every merged row.
- Seed the key_set hash via a hash slice instead of building an intermediate list, halving allocations for large primary result sets.
- Cache the removed-column list lazily in _removed_list (invalidated by remove_column) to avoid rebuilding keys(%_removed_cols) on every query.
- Iterate base rows directly from the indexed arrayref instead of copying into @base_rows, eliminating one array allocation per qualifying key.
- Restructure remove_column guard to a single early-return that covers both undef and empty-string inputs (boolean reduction).
- Remove dead store: _joined_query no longer evaluates had_criteria[0] for the primary database (it is never read).
- Remove spurious // {} fallback in _partition_criteria: _col_unrename entries are always hashrefs by construction.
- Harden AUTOLOAD regex: possessive quantifier \w++ prevents backtracking; $ anchor replaced by \z (never matches a trailing newline); /x modifier with inline comments added. Private-method guard replaced with a substr() check, eliminating a second regex entirely.
- Bug Fixes
- Fix heap-address leakage via collision_prefix: _build_col_index now rejects non-string values (refs) immediately, croaking with error_invalid_prefix before any column name is constructed. Mirrors the existing join_map value type guard.
- Fix filter reference aliasing: the filters constructor parameter and the add_database filter option are now deep-copied (_copy_filters / _copy_criteria helpers) so post-construction mutation of the caller's hashref cannot widen the logical view or bypass row-security guarantees.
Documentation
Modules
Read-only combined view across two or more Database::Abstraction objects