Revision history for Database::Join

0.002.0	Fri Sep 11 02:07:01 PM EDT 2026
	[ 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.

0.001.1	Sun Aug 23 03:29:39 PM EDT 2026
	[ Bug fixes ]
	- Fix t/edge_cases.t false failures on CPAN Testers: heap-address guard tests
	  now inspect only the first line of $@ (the error text) rather than the full
	  exception string including croak's stack trace, which naturally contains
	  object addresses.
	  Fixes https://matrix.perl-magpie.org/results/def96e6c-9e2e-11f1-af92-fa432959d47e

0.001.0	Fri Aug 21 08:54:30 PM EDT 2026
    - Initial CPAN release.
    - Read-only combined view across two or more Database::Abstraction objects
      joined on a shared key column.
    - Supports left, inner, and outer join types.
    - Per-database base filters with AND-merge semantics for compound criteria.
    - join_map for cross-name join-key column support.
    - add_database for runtime extension of the logical view.
    - remove_column / remove_columns for hiding columns from callers.
    - set_logger for logger propagation to all component databases.
    - AUTOLOAD column-shortcut delegation.