[Koha-zebra] RE: [Koha-devel] Building zebradb
Sebastian Hammer
quinn at indexdata.com
Sun Mar 12 16:03:02 CET 2006
Tümer Garip wrote:
>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
>
>
It might be a good idea to take 1.4 for a spin.. there's been some
changes to the ISAM system. It should otherwise do everythiung the
current server does, and more.
>>>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 wouldn't be too surprised if this was caused by the <collection>
wrapper.. Zebra 1.4 can be configured to look for data at a certain
level of the DOM tree -- 1.3 assumed the root element is the root
element of the record.
>>>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.
>
>
The magic is simply updating multiple records at the same time, in one
go -- something that is not possible though ZOOM today.
>>>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.
>
>
Well, they are useless when the problem is caused by a bug in Zebra, as
seems to be the case here. Clearly, the error is not detected until it's
too late. It would be very helpful if we could discover some sequence of
updates that reliably recreated this..
but I'd see this as another good reason for taking 1.4 for a spin. As I
say, there have been notable changes made to the indexing subsystem --
it may be that this is a problem that has been fixed or eliminated by
some other change.
>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.
>
>
Check the standard. The <collection> wrapper is optional. For my part, I
never use the <collection> wrapper when I deal with single records. I
don't know if Zebra does the right thing with it, but it seems to work
for you otherwise..
--Seb
>Thanks for your quick response
>Regards,
>
>Tumer
>
>-----Original Message-----
>From: Joshua Ferraro []
>Sent: Sunday, March 12, 2006 7:06 AM
>To: koha-devel at nongnu.org; tgarip at neu.edu.tr
>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 at indexdata.com>
>-----
>
>
>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 at neu.edu.tr> -----
>>
>>
>>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 at nongnu.org
>>http://lists.nongnu.org/mailman/listinfo/koha-devel
>>
>>----- End forwarded message -----
>>
>>
>>
>>
>>
>
>
>
--
Sebastian Hammer, Index Data
quinn at indexdata.com www.indexdata.com
Ph: (603) 209-6853
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