Re: [Archive-access-discuss] indexing best practicesWayback 1.x.xIndexers

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Actually, I was wrong about the 1.7.1-SNAPSHOT version of Wayback. In my experiments, it doesn’t ignore the revisit record, but rather indexes it as if it was NOT deduplicated. This means deduplicated records actually break playback, because you just get sent back an empty payload instead being re-directed to the older copy! I'll try to start setting up some test cases for these.

The current (2nd generation?) deduplicated record style (keeping the HTTP response headers in the revisit record because only the payload is checksummed), implies that reconstruction of the original response can only be guaranteed if you combine both the original and the revisit records. i.e. the CDX would have to contain references to both records in order to ensure fidelity of playback - it's only optional if you are sure the response headers won’t cause significant problems.

Andy

> -----Original Message-----
> From: Kristinn Sigurðsson [mailto:kri...@la...]
> Sent: 06 June 2013 17:24
> To: arc...@li...
> Subject: Re: [Archive-access-discuss] indexing best practicesWayback
> 1.x.xIndexers
> 
> A question on the indexing of de-duplicated records ... are they of any use as
> Wayback is currently implemented?
> 
> The warc/revisit record in the CDX file will point at the WARC that contains
> that revisit record. That record does not give any indication as to where the
> actual payload is found. That can only be inferred as same URL, earliest date
> prior to this. An inference that may or may not be accurate.
> 
> The crawl logs I have, contain a bit more detail and I was planning on mining
> them to generate 'deduplication' cdx files that would augment the ones
> generated from WARCs and ARCs (especially necessary for the ARCs as they
> have no record of the duplicates).
> 
> It seems to me, that for deduplicated content CDX files really need to contain
> two file+offset values. One for the payload and another (optional one!) for
> the warc/revisit record.
> 
> Or maybe I've completely missed something.
> 
> - Kris
> 
> 
> 
> 
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> -------------------------------------------------------------------------
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> > -----Original Message-----
> > From: Jackson, Andrew [mailto:And...@bl...]
> > Sent: 6. júní 2013 15:17
> > To: Jones, Gina; arc...@li...
> > Subject: Re: [Archive-access-discuss] indexing best practices Wayback
> > 1.x.xIndexers
> >
> > The latest versions of Wayback still seem to have major problems. The
> > 1.7.1-SNAPSHOT line appears to ignore de-duplication records, although
> > this is confused by the fact that H3/Wayback has recently been changed
> > so that de-duplication records are not empty, but rather they contain
> > the headers of the response (in case only the payload of the resource
> > itself was unchanged). However, recent Wayback versions *require* this
> > header, which breaks playback in older (but WARC-spec compliant) WARC
> > files with empty de-duplication records.
> >
> > This appears to be the same in the 1.8.0-SNAPSHOT line, but other
> > regressions mean I can't use that version (it has started refusing to
> > accept as valid some particular compressed WARC files that the
> > 1.7.1-SNAPSHOT line copes with just fine).
> >
> > Best wishes,
> > Andy Jackson
> >
> > > -----Original Message-----
> > > From: Jones, Gina [mailto:gj...@lo...]
> > > Sent: 04 June 2013 19:27
> > > To: arc...@li...
> > > Subject: [Archive-access-discuss] indexing best practices Wayback
> > > 1.x.xIndexers
> > >
> > > We have not found issues here at the Library as our collection has
> > gotten
> > > bigger.  In the past, we have had separate access points to the
> > each
> > > "collection" but are in the process of combining our content into
> > one
> > access
> > > point for a more cohesive collection.
> > >
> > > However, we have found challenges in indexing and combining those
> > > indexes, specifically due to deduplicated content.  We have content
> > > beginning in 2009 that has been deduplicated using the WARC/revisit
> > field.
> > >
> > > This is what we have think we have figured out.  If anyone has any
> > other
> > > information on these indexers, we would love to know about it.  We
> > posted
> > > a question to the listserv about 2 years ago and didn't get any
> > comments
> > > back:
> > >
> > > Wayback 1.4.x Indexers
> > > -The Wayback 1.4.2 indexer produces "warc/revisit" fields in the
> > file
> > content
> > > index that Wayback 1.4.2 cannot process and display.
> > >
> > > -When we re-indexed the same content with Wayback 1.4.0 indexer,
> > > Wayback was able to handle the revisit entries. Since the
> > "warc/revisit" field
> > > didn't exist at the time that Wayback 1.4.0 was released, we
> > suppose
> > that
> > > Wayback 1.4.0 responds to those entries as it would to any date
> > instance link
> > > where content was missing - by redirecting to the next most
> > temporally-
> > > proximate capture.
> > >
> > > -Wayback 1.6.0 can handle file content indexes with "warc/revisit"
> > fields, as
> > > well as the older 1.4.0 file content indexes
> > >
> > > -We have been unable to get Wayback 1.6.0 indexer to run on an AIX
> > server.
> > >
> > > -Wayback 1.6.0 indexer writes an alpha key code to the top line of
> > the
> > file
> > > content index. If you are merging indexes and resorting manually,
> > be
> > sure to
> > > remove that line after the index is generated.
> > >
> > > Combining cdx's from multiple indexers
> > >
> > > -As for the issue on combining the indexes, it has to do with the
> > number of
> > > fields that 1.4.0 / 1.4.2 and 1.6.X generate. The older version
> > generates a
> > > different version of the index, with a different subset of fields.
> > >
> > > -Wayback 1.6.0 can handle both indexes, so it doesn't matter if you
> > have
> > > your content indexed with either of the two. However, if you plan
> > to
> > > combine the indexes into one big index, they need to match.
> > >
> > > -The specific problem we had was with sections of an ongoing crawl.
> > 2009
> > > content was indexed with 1.4.X, but 2009+2010 content was indexed
> > with
> > > 1.6.X, so if we merge and sort, we would get the 2009 entries
> > twice,
> > because
> > > they do not match exactly (different number of fields).
> > >
> > > -The field configurations for the two versions (as we have them
> > are)
> > >
> > > 1.4.2: CDX N b h m s k r V g
> > > 1.6.1: CDX N b a m s k r M V g
> > >
> > > For definitions of the fields here is an old reference:
> > > http://archive.org/web/researcher/cdx_legend.php
> > >
> > >
> > > Gina Jones
> > > Ignacio Garcia del Campo
> > > Laura Graham
> > >
> > >
> > > -----Original Message-----
> > > From: arc...@li...
> > [mailto:archive-
> > > acc...@li...]
> > > Sent: Tuesday, June 04, 2013 8:03 AM
> > > To: arc...@li...
> > > Subject: Archive-access-discuss Digest, Vol 78, Issue 2
> > >
> > > Send Archive-access-discuss mailing list submissions to
> > >     arc...@li...
> > >
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> > > Contents of Archive-access-discuss digest..."
> > >
> > >
> > > Today's Topics:
> > >
> > >    1. Best practices for indexing a growing 2+      billion document
> > >       collection (Kristinn Sigur?sson)
> > >    2. Re: Best practices for indexing a growing     2+      billion
> > document
> > >       collection (Erik Hetzner)
> > >    3. Re: Best practices for indexing a growing 2+  billion document
> > >       collection (Colin Rosenthal)
> > >
> > >
> > > -------------------------------------------------------------------
> > ---
> > >
> > > Message: 1
> > > Date: Mon, 3 Jun 2013 11:39:40 +0000
> > > From: Kristinn Sigur?sson <kri...@la...>
> > > Subject: [Archive-access-discuss] Best practices for indexing a
> > >     growing 2+      billion document collection
> > > To: "arc...@li..."
> > >     <arc...@li...>
> > > Message-ID:
> > >     <E48...@bl...>
> > > Content-Type: text/plain; charset="utf-8"
> > >
> > > Dear all,
> > >
> > > We are planning on updating our Wayback installation and I would
> > like
> > to poll
> > > your collective wisdom on the best approach for managing the
> > Wayback
> > > index.
> > >
> > > Currently, our collection is about 2.2 billion items. It is also
> > growing at a rate of
> > > approximately 350-400 million records per year.
> > >
> > > The obvious approach would be to use a sorted CDX file (or files)
> > as
> > the
> > > index. I'm, however, concerned about its performance at this scale.
> > > Additionally, updating a CDX based index can be troublesome.
> > Especially as
> > > we would like to update it continuously as new material is
> > ingested.
> > >
> > > Any relevant experience and advice you could share on this topic
> > would
> > be
> > > greatly appreciated.
> > >
> > >
> > > Best regards,
> > > Mr. Kristinn Sigur?sson
> > > Head of IT
> > > National and University Library of Iceland
> > >
> > >
> > >
> > >
> > >
> > ---------------------------------------------------------------------
> > ---
> > -
> > > Landsb?kasafn ?slands - H?sk?lab?kasafn | Arngr?msg?tu 3 - 107
> > Reykjav?k
> > > S?mi/Tel: +354 5255600 | www.landsbokasafn.is
> > >
> > ---------------------------------------------------------------------
> > ---
> > -
> > > fyrirvari/disclaimer - http://fyrirvari.landsbokasafn.is
> > >
> > > ------------------------------
> > >
> > > Message: 2
> > > Date: Mon, 03 Jun 2013 11:49:04 -0700
> > > From: Erik Hetzner <eri...@uc...>
> > > Subject: Re: [Archive-access-discuss] Best practices for indexing a
> > >     growing 2+      billion document collection
> > > To: Kristinn Sigur?sson <kri...@la...>
> > > Cc: "arc...@li..."
> > >     <arc...@li...>
> > > Message-ID: <201...@ma...>
> > > Content-Type: text/plain; charset="utf-8"
> > >
> > > At Mon, 3 Jun 2013 11:39:40 +0000,
> > > Kristinn Sigur?sson wrote:
> > > >
> > > > Dear all,
> > > >
> > > > We are planning on updating our Wayback installation and I would
> > like
> > > > to poll your collective wisdom on the best approach for managing
> > the
> > > > Wayback index.
> > > >
> > > > Currently, our collection is about 2.2 billion items. It is also
> > > > growing at a rate of approximately 350-400 million records per
> > year.
> > > >
> > > > The obvious approach would be to use a sorted CDX file (or files)
> > as
> > > > the index. I'm, however, concerned about its performance at this
> > > > scale. Additionally, updating a CDX based index can be
> > troublesome.
> > > > Especially as we would like to update it continuously as new
> > material
> > > > is ingested.
> > > >
> > > > Any relevant experience and advice you could share on this topic
> > would
> > > > be greatly appreciated.
> > >
> > > Hi Kristinn,
> > >
> > > We use 4 different CDX files. One is updated every ten minutes, one
> > hourly,
> > > one daily, and one monthly. We use the unix sort command to sort.
> > This
> > has
> > > worked pretty well for us. We aren?t doing it in the most efficient
> > manner,
> > > and we will probably switch to sorting with hadoop at some point,
> > but
> > it
> > > works pretty well.
> > >
> > > best, Erik
> > > -------------- next part -------------- Sent from my free software
> > > system <http://fsf.org/>.
> > >
> > > ------------------------------
> > >
> > > Message: 3
> > > Date: Tue, 4 Jun 2013 12:17:18 +0200
> > > From: Colin Rosenthal <cs...@st...>
> > > Subject: Re: [Archive-access-discuss] Best practices for indexing a
> > >     growing 2+      billion document collection
> > > To: arc...@li...
> > > Message-ID: <51A...@st...>
> > > Content-Type: text/plain; charset="UTF-8"; format=flowed
> > >
> > > On 06/03/2013 08:49 PM, Erik Hetzner wrote:
> > > > At Mon, 3 Jun 2013 11:39:40 +0000, Kristinn Sigur?sson wrote:
> > > >> Dear all,
> > > >>
> > > >> We are planning on updating our Wayback installation and I would
> > like
> > > >> to poll your collective wisdom on the best approach for managing
> > the
> > > >> Wayback index.
> > > >>
> > > >> Currently, our collection is about 2.2 billion items. It is also
> > > >> growing at a rate of approximately 350-400 million records per
> > year.
> > > >>
> > > >> The obvious approach would be to use a sorted CDX file (or
> > files)
> > as
> > > >> the index. I'm, however, concerned about its performance at this
> > > >> scale. Additionally, updating a CDX based index can be
> > troublesome.
> > > >> Especially as we would like to update it continuously as new
> > material
> > > >> is ingested.
> > > >>
> > > >> Any relevant experience and advice you could share on this topic
> > > >> would be greatly appreciated.
> > > > Hi Kristinn,
> > > >
> > > > We use 4 different CDX files. One is updated every ten minutes,
> > one
> > > > hourly, one daily, and one monthly. We use the unix sort command
> > to
> > > > sort. This has worked pretty well for us. We aren?t doing it in
> > the
> > > > most efficient manner, and we will probably switch to sorting
> > with
> > > > hadoop at some point, but it works pretty well.
> > > >
> > > > best, Erik
> > > Hi Kristinn,
> > >
> > > Our strategy for building cdx indexes is described at
> > >
> >
> https://sbforge.org/display/NASDOC321/Wayback+Configuration#WaybackC
> > > onfiguration-AggregatorApplication
> > > .
> > >
> > > Essentially we have multiple threads creating unsorted cdx files
> > for
> > all new
> > > arc/warc files in the archive. These are then sorted and merged
> > into
> > an
> > > intermediate index file. When the intermediate file grows larger
> > than
> > 100MB,
> > > it is merged with the current main index file, and when that grows
> > larger than
> > > 50GB we rollover to a new main index file. We currently have about
> > 5TB
> > total
> > > cdx index. This includes 16 older cdx files of size 150GB-300GB,
> > built
> > by
> > > handrolled scripts before we had a functional automatic indexing
> > workflow.
> > >
> > > We would be fascinated to hear if anyone is using an entirely
> > different
> > > strategy (e.g. bdb) for a large archive.
> > >
> > > One of our big issues at the moment is QA of our cdx files. How can
> > we
> > be
> > > sure that our indexes actually cover all the files and records in
> > the
> > archive?
> > >
> > > Colin Rosenthal
> > > IT-Developer
> > > Netarkivet, Denmark
> > >
> > >
> > >
> > >
> > > ------------------------------
> > >
> > >
> > ---------------------------------------------------------------------
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> > >
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