search: improve comments around constants

We'll probably be adding more value columns like THREADID to sort
on.

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index 4d02a7c169c202ebd150ccd1e0158ab21939c56a..593040a8a285340a69465d8bd27fba357387f28a 100644 (file)
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -6,15 +6,47 @@
 package PublicInbox::Search;
 use strict;
 
-# values for searching
+# 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
+
        # TODO
-       # REPLYCNT => 4, # IMAP ANSWERED
+       # THREADID => ?
+       # 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 and UID values
+       SCHEMA_VERSION => 15,
 };
 
 use PublicInbox::Smsg;
@@ -61,33 +93,6 @@ sub load_xapian () {
 # a prefix common in patch emails
 our $LANG = 'english';
 
-use constant {
-       # 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
-       SCHEMA_VERSION => 15,
-};
-
 # note: the non-X term prefix allocations are shared with
 # Xapian omega, see xapian-applications/omega/docs/termprefixes.rst
 my %bool_pfx_external = (