% public-inbox developer manual =head1 NAME lei-store-format - lei/store format description =head1 DESCRIPTION C is a hybrid store based on L ("extindex") combined with L ("v2") for blob storage. While v2 is ideal for archiving a single public mailing list; it was never intended for personal mail nor storing multiple blobs of the "same" message. As with extindex, it can index disparate C headers belonging to the "same" message with different git blob OIDs. Unlike v2 and extindex, C headers are NOT required; allowing unsent draft messages to be stored and indexed. =head1 DIRECTORY LAYOUT Blob storage exists in the form of v2-style epochs. These epochs are under the C directory (instead of C) to prevent them from being accidentally treated as a v2 inbox. =head2 INDEX OVERVIEW AND DEFINITIONS $EPOCH - Integer starting with 0 based on time $SCHEMA_VERSION - DB schema version (for Xapian) $SHARD - Integer starting with 0 based on parallelism ~/.local/share/lei/store - ipc.lock # lock file for internal lei IPC - local/$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 =head2 XREF3 DEDUPLICATION Index deduplication follows extindex, see L for more information. =head2 BLOB DEDUPLICATION The contents of C 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 C, C and similar headers to allow troubleshooting. =head2 VOLATILE METADATA Keywords and label information (as described in RFC 8621 for JMAP) is stored in existing Xapian shards (C). It is possible to search for messages matching labels and keywords using C and C, 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. =head1 IPC When L is run in daemon mode, L is used on C is used to serialize writes to C across multiple internal lei workers while minimizing commits. =head1 CAVEATS Reindexing and synchronization is not yet supported. =head1 THANKS Thanks to the Linux Foundation for sponsoring the development and testing. =head1 COPYRIGHT Copyright 2021 all contributors L License: AGPL-3.0+ L =head1 SEE ALSO L, L