On 14/09/10 14:24 -0500, Patrick Goetz wrote:
There's been some discussion on the Debian cyrus list about how to
automate upgrades from cyrus 2.n.k to cyrus 2.m.j. Jeroen van
Meeuwen (on both lists) suggested that the cyrus RPM package features
a utility called cyrus-imapd.cvt_cyrusdb_all which might be useful
for this.
I've been looking at this script, and it mostly appears to be using
cvt_cyrusdb to convert particular db files to Cyrus skiplists and
then back again to the original db backend format. I can't follow
the script completely as it seems to rely on DB configuration details
found in the imapd.conf file I don't have in my Debian 2.1.16 imap
server, and it's also not clear how the script is run.
This raises a number of questions, though:
1.
Cyrus skiplists? I thought all the DB files were in Berkeley DB
format. I tried to find some documentation on skiplists, but only
found an old message to the developer list from Bron Gondwana
discussing skiplist bugs
(http://markmail.org/message/zbaq765brbg2acfj).
The current imapd.conf hints at the available data types for each cyrus
database. Depending on the option, the following database types are
available (in 2.3.16):
annotation_db: skiplist
Allowed values: berkeley, berkeley-hash, skiplist
duplicate_db: berkeley-nosync
Allowed values: berkeley, berkeley-nosync, berkeley-hash,
berkeley-hash-nosync, skiplist, sql
mboxkey_db: skiplist
Allowed values: berkeley, skiplist
mboxlist_db: skiplist
Allowed values: flat, berkeley, berkeley-hash, skiplist
ptscache_db: berkeley
Allowed values: berkeley, berkeley-hash, skiplist
quota_db: quotalegacy
Allowed values: flat, berkeley, berkeley-hash, skiplist, sql, quotalegacy
seenstate_db: skiplist
Allowed values: flat, berkeley, berkeley-hash, skiplist
subscription_db: flat
Allowed values: flat, berkeley, berkeley-hash, skiplist
statuscache_db: berkeley-nosync
Allowed values: berkeley, berkeley-nosync, berkeley-hash,
berkeley-hash-nosync, skiplist
tlscache_db: berkeley-nosync
Allowed values: berkeley, berkeley-nosync, berkeley-hash,
berkeley-hash-nosync, skiplist, sql
userdeny_db: flat
Allowed values: flat, berkeley, berkeley-hash, skiplist, sql
http://www.cyrusimap.org/docs/cyrus-imapd/2.3.16/internal/database-formats.php
has some discussion of the databases.
I don't know why the (rpm) upgrade script chose skiplist as an
intermediate format, rather than flat. Perhaps skiplist hasn't changed much
between major versions, and offers a speed benefit.
The script seems to use the file command to determine the current database
types, since they can be changed by an admin.
2.
The Redhat cvt_cyrusdb_all script seems to assume a specific set of
database files. Is the set of cyrus imap DB files fixed, and if so
what are they? Is there any documentation on what each database file
contains? This would be very useful to people trying to convert older
cyrus IMAP installations to new ones.
As far as skiplist, that seems to be a proprietary format.
As far as I can tell, all databases use the same underlying structure
(except for quotalegacy), which is defined in the database-formats above.
flat: ASCII text file
berkeley: berkeley db (with safer values).
berkeley-nosync: berkeley db with the DB_TXN_NOSYNC flag set.
berkeley-hash: berkeley db with the DB_HASH flag set.
berkeley-hash-nosync: berkeley db with both DB_TXN_NOSYNC and DB_HASH
flags?
sql: A mysql, pgsql, or sqlite store.
quotalegacy: See database-formats
skiplist: ?
With cyrus version 2.3.13 and above, the cyr_dbtool can be used to insert
and remove records manually for each database.
--
Dan White
