# <www.danga.com>LiveJournal

DROP TABLE IF EXISTS domain;
CREATE TABLE domain (
   dmid         SMALLINT UNSIGNED NOT NULL,
   PRIMARY KEY  (dmid),
   
   namespace    VARCHAR(255),
   UNIQUE (namespace)           # LiveJournal:<www.livejournal.com>, FotoBilder:<www.picpix.com>

);

# classes are tied to domains.  domains can have classes of items
# with different mindevcounts.
#
# a minimum devcount is the number of copies the system tries to
# maintain for files in that class
#
# unspecified classname means classid=0 (implicit class), and that
# implies mindevcount=2
#
DROP TABLE IF EXISTS class;
CREATE TABLE class (
      dmid          SMALLINT UNSIGNED NOT NULL,
      classid       TINYINT UNSIGNED NOT NULL,
      PRIMARY KEY (dmid,classid),
      classname     VARCHAR(50),
      UNIQUE      (dmid,classname),
      mindevcount   TINYINT UNSIGNED NOT NULL
);

# the length field is only here for easy verifications of content
# integrity when copying around.  no sums or content types or other
# metadata here.  application can handle that.
#
# classid is what class of file this belongs to.  for instance, on fotobilder
# there will be a class for original pictures (the ones the user uploaded)
# and a class for derived images (scaled down versions, thumbnails, greyscale, etc)
# each domain can setup classes and assign the minimum redundancy level for 
# each class.  fotobilder will use a 2 or 3 minimum copy redundancy for original
# photos and and a 1 minimum for derived images (which means the sole device
# for a derived image can die, bringing devcount to 0 for that file, but 
# the application can recreate it from its original)
DROP TABLE IF EXISTS file;
CREATE TABLE file (
   fid          INT UNSIGNED NOT NULL,
   PRIMARY KEY  (fid),

   dmid          SMALLINT UNSIGNED NOT NULL,
   dkey           VARCHAR(255),     # domain-defined.  LJ:  "<userid>-<blobtype>-<blobid>"
   UNIQUE dkey  (dmid, dkey),

   length        INT UNSIGNED,        # 4GB limit

   classid       TINYINT UNSIGNED NOT NULL,
   devcount      TINYINT UNSIGNED NOT NULL,
   INDEX devcount (dmid,classid,devcount)
);

DROP TABLE IF EXISTS tempfile;
CREATE TABLE tempfile (
   fid          INT UNSIGNED NOT NULL AUTO_INCREMENT,
   PRIMARY KEY  (fid),

   createtime   INT UNSIGNED NOT NULL,
   classid      TINYINT UNSIGNED NOT NULL,
   dmid          SMALLINT UNSIGNED NOT NULL,
   dkey           VARCHAR(255),
   devids       VARCHAR(60)
);

# files marked for death when their key is overwritten.  then they get a new
# fid, but since the old row (with the old fid) had to be deleted immediately,
# we need a place to store the fid so an async job can delete the file from
# all devices.
DROP TABLE IF EXISTS file_to_delete;
CREATE TABLE file_to_delete (
   fid  INT UNSIGNED NOT NULL,
   PRIMARY KEY (fid)
);

# if the replicator notices that a fid has no sources, that file gets inserted
# into the unreachable_fids table.  it is up to the application to actually
# handle fids stored in this table.
DROP TABLE IF EXISTS unreachable_fids;
CREATE TABLE unreachable_fids (
   fid        INT UNSIGNED NOT NULL,
   lastupdate INT UNSIGNED NOT NULL,
   PRIMARY KEY (fid),
   INDEX (lastupdate)
);

# what files are on what devices?  (most likely physical devices,
# as logical devices of RAID arrays would be costly, and mogilefs
# already handles redundancy)
#
# the devid index lets us answer "What files were on this now-dead disk?"
#
DROP TABLE IF EXISTS file_on;
CREATE TABLE file_on (
   fid          INT UNSIGNED NOT NULL,
   devid        MEDIUMINT UNSIGNED NOT NULL,
   PRIMARY KEY (fid, devid), 
   INDEX (devid)
);

# if application or framework detects an error in one of the duplicate files
# for whatever reason, it can register its complaint and the framework
# will do some verifications and fix things up w/ an async job
# MAYBE: let application tell us the SHA1/MD5 of the file for us to check
#        on the other devices?
DROP TABLE IF EXISTS file_on_corrupt;
CREATE TABLE file_on_corrupt (
   fid          INT UNSIGNED NOT NULL,
   devid        MEDIUMINT UNSIGNED NOT NULL,
   PRIMARY KEY (fid, devid)
);

DROP TABLE IF EXISTS device;
CREATE TABLE device (
   devid   MEDIUMINT UNSIGNED NOT NULL,
   PRIMARY KEY (devid),

   hostid     MEDIUMINT UNSIGNED NOT NULL,

   status  ENUM('alive','dead','down'),
   INDEX   (status),

   mb_total   MEDIUMINT UNSIGNED,
   mb_used    MEDIUMINT UNSIGNED,
   mb_asof    INT UNSIGNED

);

DROP TABLE IF EXISTS host;
CREATE TABLE host (
   hostid     MEDIUMINT UNSIGNED NOT NULL,
   PRIMARY KEY (hostid),

   status     ENUM('alive','dead','down'),
   http_port  MEDIUMINT UNSIGNED DEFAULT 7500,
   http_get_port MEDIUMINT UNSIGNED,

   hostname   VARCHAR(40),
   UNIQUE     (hostname),
   hostip     VARCHAR(15),
   UNIQUE     (hostip),
   altip      VARCHAR(15),
   UNIQUE     (altip),
   altmask    VARCHAR(18),

   remoteroot  VARCHAR(60)
);