ITS#8156 Fix MDB_MAXKEYSIZE doc

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 71852b1f6e107711932b5e3de82064000af28b7c..6bdf3151dcca23220157c1efa3caa2f562e61374 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -446,12 +446,17 @@ static txnid_t mdb_debug_start;
        /**     The version number for a database's lockfile format. */
 #define MDB_LOCK_VERSION        1
 
-       /**     @brief The max size of a key we can write, or 0 for dynamic max.
+       /**     @brief The max size of a key we can write, or 0 for computed max.
         *
-        *      Define this as 0 to compute the max from the page size.  511
-        *      is default for backwards compat: liblmdb <= 0.9.10 can break
-        *      when modifying a DB with keys/dupsort data bigger than its max.
-        *      #MDB_DEVEL sets the default to 0.
+        *      This macro should normally be left alone or set to 0.
+        *      Note that a database with big keys or dupsort data cannot be
+        *      reliably modified by a liblmdb which uses a smaller max.
+        *      The default is 511 for backwards compat, or 0 when #MDB_DEVEL.
+        *
+        *      Other values are allowed, for backwards compat.  However:
+        *      A value bigger than the computed max can break if you do not
+        *      know what you are doing, and liblmdb <= 0.9.10 can break when
+        *      modifying a DB with keys/dupsort data bigger than its max.
         *
         *      Data items in an #MDB_DUPSORT database are also limited to
         *      this size, since they're actually keys of a sub-DB.  Keys and