INDEX OVERVIEW AND DEFINITIONS¶

  $EPOCH - Integer starting with 0 based on time
  $SCHEMA_VERSION - DB schema version (for Xapian)
  $SHARD - Integer starting with 0 based on parallelism
  ~/.local/share/lei/store
  - local/$EPOCH.git                # normal bare git repositories
  - mail_sync.sqlite3               # sync state IMAP, Maildir, NNTP

Additionally, the following share the same roles they do in extindex:

  - ei.lock                         # lock file to protect global state
  - ALL.git                         # empty, alternates for local/*.git
  - ei$SCHEMA_VERSION/$SHARD        # per-shard Xapian DB
  - ei$SCHEMA_VERSION/over.sqlite3  # overview DB for WWW, IMAP
  - ei$SCHEMA_VERSION/misc          # misc Xapian DB

XREF3 DEDUPLICATION¶

Index deduplication follows extindex, see "XREF3 DEDUPLICATION" in public-inbox-extindex-format(5) for more information.

BLOB DEDUPLICATION¶

The contents of "local/*.git" repos is deduplicated by git blob object IDs (currently SHA-1). This allows multiple copies of cross-posted and personally Cc-ed messages to be stored with different "Received:", "X-Spam-Status:" and similar headers to allow troubleshooting.

VOLATILE METADATA¶

Keywords and label information (as described in RFC 8621 for JMAP) is stored in existing Xapian shards ("ei$SCHEMA_VERSION/$SHARD"). It is possible to search for messages matching labels and keywords using "L:" and "kw:", respectively. As with all data stored in Xapian indices, volatile metadata is associated with the Xapian document, thus it is shared across different blobs of the "same" message.

mail_sync.sqlite3¶

This SQLite database maintained for bidirectional mapping of git blobs to IMAP UIDs, Maildir file names, and NNTP article numbers.

It is also used for retrieving messages from Maildirs indexed by lei-index(1).