The board export routes buffered the entire board in memory before sending:
JSON export built one object with every card, comment, activity, checklist and
base64 attachment; CSV called that same build(); Excel additionally loaded data
it never renders (activities/checklists/subtasks/rules) and did O(n^2)
result.cards.find() lookups. On big boards this peaked at gigabytes and could
exceed V8's max string length.
Now:
- Exporter.buildStream(res) writes the JSON document straight to the response a
document at a time from raw Mongo cursors, encoding each attachment file to
base64 in 3-byte-aligned chunks. Same _format/keys, so import round-trips.
- Exporter.buildCsvStream(res) keeps only the small lookup tables in memory and
streams cards from a cursor, writing one CSV/TSV row at a time.
- ExporterExcel uses the exceljs streaming WorkbookWriter, committing each row
to the response, drops the unused collections, and resolves parent/comment
card titles via an id->title map instead of scanning all cards.
Peak memory stays flat regardless of board size.
xet7
Jan Küster