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From "Alexander S. (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SOLR-5463) Provide cursor/token based "searchAfter" support that works with arbitrary sorting (ie: "deep paging")
Date Thu, 29 May 2014 15:30:04 GMT

    [ https://issues.apache.org/jira/browse/SOLR-5463?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14012449#comment-14012449
] 

Alexander S. commented on SOLR-5463:
------------------------------------

I have another idea about cursors implementation. That's just an idea, I am not sure if that's
possible to do.

Is it possible to use cursors together with "start" and "rows" parameters? That would allow
to use pagination and draw links for prev, next, 1, 2, 3, n+1 pages, as we can do now. So
that instead of using cursorMark we'll use cursorName, which could be a static. So the request
start:0, rows:10, cursorName:* will return first page of results and a static cursor name,
which could then be used for all other pages (i.e. start:10, rows:10, cursorName:#{received_cursor_name}).

Does that make sense?

> Provide cursor/token based "searchAfter" support that works with arbitrary sorting (ie:
"deep paging")
> ------------------------------------------------------------------------------------------------------
>
>                 Key: SOLR-5463
>                 URL: https://issues.apache.org/jira/browse/SOLR-5463
>             Project: Solr
>          Issue Type: New Feature
>            Reporter: Hoss Man
>            Assignee: Hoss Man
>             Fix For: 4.7, 5.0
>
>         Attachments: SOLR-5463-randomized-faceting-test.patch, SOLR-5463.patch, SOLR-5463.patch,
SOLR-5463.patch, SOLR-5463.patch, SOLR-5463.patch, SOLR-5463.patch, SOLR-5463.patch, SOLR-5463__straw_man.patch,
SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch,
SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch, SOLR-5463__straw_man.patch,
SOLR-5463__straw_man.patch, SOLR-5463__straw_man__MissingStringLastComparatorSource.patch
>
>
> I'd like to revist a solution to the problem of "deep paging" in Solr, leveraging an
HTTP based API similar to how IndexSearcher.searchAfter works at the lucene level: require
the clients to provide back a token indicating the sort values of the last document seen on
the previous "page".  This is similar to the "cursor" model I've seen in several other REST
APIs that support "pagnation" over a large sets of results (notable the twitter API and it's
"since_id" param) except that we'll want something that works with arbitrary multi-level sort
critera that can be either ascending or descending.
> SOLR-1726 laid some initial ground work here and was commited quite a while ago, but
the key bit of argument parsing to leverage it was commented out due to some problems (see
comments in that issue).  It's also somewhat out of date at this point: at the time it was
commited, IndexSearcher only supported searchAfter for simple scores, not arbitrary field
sorts; and the params added in SOLR-1726 suffer from this limitation as well.
> ---
> I think it would make sense to start fresh with a new issue with a focus on ensuring
that we have deep paging which:
> * supports arbitrary field sorts in addition to sorting by score
> * works in distributed mode
> {panel:title=Basic Usage}
> * send a request with {{sort=X&start=0&rows=N&cursorMark=*}}
> ** sort can be anything, but must include the uniqueKey field (as a tie breaker) 
> ** "N" can be any number you want per page
> ** start must be "0"
> ** "\*" denotes you want to use a cursor starting at the beginning mark
> * parse the response body and extract the (String) {{nextCursorMark}} value
> * Replace the "\*" value in your initial request params with the {{nextCursorMark}} value
from the response in the subsequent request
> * repeat until the {{nextCursorMark}} value stops changing, or you have collected as
many docs as you need
> {panel}



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