[[e-mail]: RE: [Koha-devel] Building zebradb]

[Joshua Ferraro-3]

----- Forwarded message from Tümer Garip <tgarip@...> -----


Hi,

To clear some issues with Sebastian:
>>Again, I'd be keen to know which Zebra version you're running?
1- I am using Zebra version 1.3.34
>>Why not ask for the records in ISO2709 from Zebra if that's what you
>>want to work with (when records are loaded in MARCXML, it can spit out

>>either 2709 or XML)? Or is it just that you want to have them in
>>MARC::Record? At any rate, ISO2709 is a more compact exchange format,
so
>>it seems to make sense to use it.
2- Definitely correct and theoretically yes, but I keep saying that when
you feed zebra with MARCXML you CAN NOT get back MARC records. All you
get back is the leader and lots of blank space. I tried it with
YAZ-client as well.
I have reported this as a bug on indexdata list but never got an answer.
>> I get update times around .5-.7 seconds,
3- .4 or .5 is what we get as well. Stupidly enough write the file to
disk use zebraidx and you get .04-.09 and even faster times. What magic
zebraidx use that ZOOM does not know I donno.
>>Now *that* is nasty. Do you have *any* way of consistently recreating
>>the problem? Even if you don't, I'm sure Adam and the Zebra crew would

>>like to see some stack traces of those crashes!!
4- The problem is intermittent. I'll try to provide details when it
reoccurs. What it says is  "Fatal error: inconsistent register" from
then on you have to throw the zebradatabase away and rebuild everything.
You cannot fallback to the working state. Shadow system was supposed to
do this. If something is gone wrong when you commit it should not go and
mess the whole database but just refuse to do it and let you wipe off
the last update commit operation. But you can not do that. So unless I
have missed something shadow files are useless.

Here is some more to think about zebra:
1- The MARCXML we feed into zebra is
<collection><record></record></collection> package. When you get it back
it is  still like that as supposed to be.  But if you feed zebra with
iso2709 marc records and ask back from zebra xml records you get back
<record></record> package no <collection> wrapping around it. Although
this is not a problem currently, I still do not like zebra doing that.
Its MARC to XML conversion should follow standarts rather than create
its own.

Thanks for your quick response
Regards,

Tumer

-----Original Message-----
From: Joshua Ferraro []
Sent: Sunday, March 12, 2006 7:06 AM
To: koha-devel@...; tgarip@...
Subject: [Koha-devel] Building zebradb


Tumer,

Sebastian's been good enough to respond to your post (I forwarded this
to the koha-zebra list). If you get a change, could you join koha-zebra
(if you're not already on it) and follow up -- I've a
feeling it could prove to be a very productive thread.

Cheers,

Joshua

----- Forwarded message from Sebastian Hammer <quinn@...>
-----


Hi Joshua,

Thanks for this feedback, it's very interesting. Clearly some of the
issues you describe (i.e. a lack of stability around upadets) indicate
software problems, but there's also some interesting ideas for possible
refinements or new developments which I think would be really useful to
get into the general development plans for the software... there are
more folks at ID involved in Zebra development that I'd like to get into

these thoughts... I dunno if a wiki or just a larger zebra-dev list is
in order, but it's something to think about.

Joshua Ferraro wrote:

>----- Forwarded message from Tümer Garip <tgarip@...> -----
>
>
>Hi,
>We have now put the zebra into production level systems. So here is
>some experience to share.
>
>Building the zebra database from single records is a veeeeery looong
>process. (100K records 150k items)
>
>

Yes, that confirms my expectations. We could think about building  some
kind of buffering into for first-time updating, or else the logic has to

be in the application, as you've seen... the situation is particularly
grim if shadow-indexing is enabled during indexing and every record is
committed, since this causes a sync of the disks, which could take up to

a whole second.

Also, I'm not sure which version of Zebra you're using? I've been foing
some performance-testing of Zebra for the Internet Archive, and noted
quite a difference between 1.3 and 1.4 (the CVS version) which is really

where all the development happens.

>Best method we found:
>
>1- Change zebra.cfg file to include
>
>iso2079.recordType:grs.marcxml.collection
>recordType:grs.xml.collection
>
>2- Write (or hack export.pl) to export all the marc records as one big
>chunk to the correct directory with an extension .iso2079 And system
>call "zebraidx -g iso2079 -d <dbnamehere> update records -n".
>
>This ensures that zebra knows its reading marc records rather than xml
>and builds 100K+ records in zooming speed. Your zoom module always uses

>the grs.xml filter while you can anytime update or reindex any big
>chunk of the database as long as you have marc records.
>
>
Good strategy, I think.. but of course it's weird and awkward to have to

use two different formats, especially when they both have limitations.
We really must look into handling ISO2709 from ZOOM.

Mind you, version 1.4 should be able to read multiple collection-wrapped

MARCXML records in one file, but only (AFAIK) in conjunction witht the
new XSLT-based index rules. I *would* like to try to develop a good way
to work with bibliographic data in that framework.

>3-We are still using the old API so we read the xml and use
>MARC::Record->new_from_xml( $xmldata ) A note here that we did not had
>to upgrade MARC::Record or MARC::Charset at all. Any marc created
>within KOHA is UTF8 and any marc imported into KOHA (old
>marc_subfield_tables) was correctly decoded to utf8 with char_decode of

>biblio.
>
>
Why not ask for the records in ISO2709 from Zebra if that's what you
want to work with (when records are loaded in MARCXML, it can spit out
either 2709 or XML)? Or is it just that you want to have them in
MARC::Record? At any rate, ISO2709 is a more compact exchange format, so

it seems to make sense to use it.

>4- We modified circ2.pm and items table to have item onloan field and
>mapped it to marc holdings data. Now our opac search do not call mysql
>but for the branchname.
>
>5- Average updates per day is about 2000 (circulation+cataloger). I can

>say that the speed of the zoom search which slows down during a commit
>operation is acceptable considering the speed gain we have on the
>search.
>
>
Again, I'd be keen to know which Zebra version you're running?

Beause the Internet Archive will be doing similar point-updates for
records (only a *lot* more often than 2000 times per day) I have been
looking a lot at the update speed for these small changes that only
affect a single term in a record (like a circulation code).. In my test
database of 150K records, 10K average size, I get update times around
.5-.7 seconds, which just seems intuitively faster than it should have
to be. I'm going to nudge the coders to see if we can possibly do this
better.

>6- Zebra behaves very well with searches but is very tempremental with
>updates. A queue of updates sometimes crashes the zebraserver. When the

>database crash we can not save anything even though we are using shadow

>files. I'll be reporting on this issue once we can isolate the
>problems.
>
>
Now *that* is nasty. Do you have *any* way of consistently recreating
the problem? Even if you don't, I'm sure Adam and the Zebra crew would
like to see some stack traces of those crashes!!

--Sebastian

>Regards,
>Tumer
>
>
>
>_______________________________________________
>Koha-devel mailing list
>Koha-devel@...
>http://lists.nongnu.org/mailman/listinfo/koha-devel
>
>----- End forwarded message -----
>
>
>

--
Sebastian Hammer, Index Data
quinn@...   www.indexdata.com
Ph: [phone]



----- End forwarded message -----

--
Joshua Ferraro               VENDOR SERVICES FOR OPEN-SOURCE SOFTWARE
President, Technology       migration, training, maintenance, support
LibLime                                Featuring Koha Open-Source ILS
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----- End forwarded message -----

--
Joshua Ferraro               VENDOR SERVICES FOR OPEN-SOURCE SOFTWARE
President, Technology       migration, training, maintenance, support
LibLime                                Featuring Koha Open-Source ILS
jmf@... |Full Demos at http://liblime.com/koha |1(888)KohaILS


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