+# values for searching, changing the numeric value breaks
+# compatibility with old indices (so don't change them it)
+use constant {
+ TS => 0, # Received: header in Unix time (IMAP INTERNALDATE)
+ YYYYMMDD => 1, # Date: header for searching in the WWW UI
+ DT => 2, # Date: YYYYMMDDHHMMSS
+
+ # added for public-inbox 1.6.0+
+ BYTES => 3, # IMAP RFC822.SIZE
+ UID => 4, # IMAP UID == NNTP article number == Xapian docid
+ THREADID => 5, # RFC 8474, RFC 8621
+
+ # TODO
+ # REPLYCNT => ?, # IMAP ANSWERED
+
+ # SCHEMA_VERSION history
+ # 0 - initial
+ # 1 - subject_path is lower-cased
+ # 2 - subject_path is id_compress in the index, only
+ # 3 - message-ID is compressed if it includes '%' (hack!)
+ # 4 - change "Re: " normalization, avoid circular Reference ghosts
+ # 5 - subject_path drops trailing '.'
+ # 6 - preserve References: order in document data
+ # 7 - remove references and inreplyto terms
+ # 8 - remove redundant/unneeded document data
+ # 9 - disable Message-ID compression (SHA-1)
+ # 10 - optimize doc for NNTP overviews
+ # 11 - merge threads when vivifying ghosts
+ # 12 - change YYYYMMDD value column to numeric
+ # 13 - fix threading for empty References/In-Reply-To
+ # (commit 83425ef12e4b65cdcecd11ddcb38175d4a91d5a0)
+ # 14 - fix ghost root vivification
+ # 15 - see public-inbox-v2-format(5)
+ # further bumps likely unnecessary, we'll suggest in-place
+ # "--reindex" use for further fixes and tweaks:
+ #
+ # public-inbox v1.5.0 adds (still SCHEMA_VERSION=15):
+ # * "lid:" and "l:" for List-Id searches
+ #
+ # v1.6.0 adds BYTES, UID and THREADID values
+ SCHEMA_VERSION => 15,
+};