Using symlinks to alias cores

[Andrew Clegg <an...@gmail.com>]

Another question...

I have a series of cores representing historical data, only the most recent
of which gets indexed to.

I'd like to alias the most recent one to 'current' so that when they roll
over I can just change the alias, and the cron jobs etc. which manage
indexing don't have to change.

However, the wiki recommends against using the ALIAS command in CoreAdmin in
a couple of places, and SOLR-1637 says it's been removed now anyway.

If I can't use ALIAS safely, is it okay to just symlink the most recent
core's instance (or data) directory to 'current', and bring it up in Solr as
a separate core? Will this be safe, as long as all index writing happens via
the 'current' core?

Or will it cause Solr to get confused and do horrible things to the index?

Thanks!

Andrew.

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Re: Using symlinks to alias cores

[Andrew Clegg <an...@gmail.com>]

Chris Hostetter-3 wrote:
> 
> a cleaner way to deal with this would be do use something like 
> RewriteRule -- either in your appserver (if it supports a feature like 
> that) or in a proxy sitting in front of Solr.
> 

I think we'll go with this -- seems like the most bulletproof way.

Cheers,

Andrew.

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Re: Using symlinks to alias cores

[Chris Hostetter <ho...@fucit.org>]

: However, the wiki recommends against using the ALIAS command in CoreAdmin in
: a couple of places, and SOLR-1637 says it's been removed now anyway.

correct, there were a lot of problems with how to cleanly/sanely deal with 
core operations on aliases -- he command may return at some future date if 
there is a better seperation between the concept of an "authoritative' 
name for a core, and aliases -- but in the meantime, i wouldn't recomend 
using it even in older versions of Solr where it (sort of) worked.

: If I can't use ALIAS safely, is it okay to just symlink the most recent
: core's instance (or data) directory to 'current', and bring it up in Solr as
: a separate core? Will this be safe, as long as all index writing happens via
: the 'current' core?

i would not recommend that -- as long as you only index to one of those 
cores, and use "commits" to force the other instances to reload from disk 
there wouldn't be any errors -- but you'll wind up duplicating all of the 
internal memory strucutures (index objects, and caches)

a cleaner way to deal with this would be do use something like 
RewriteRule -- either in your appserver (if it supports a feature like 
that) or in a proxy sitting in front of Solr.

Frankly though: indexing code can usually be made fairly smart -- pretty 
much every programming langauge i nthe world makes it fairly easy to 
generate a string using the pattern 
"http://server:8983/solr/${YY-MM-DD}/update", and then you just POST to 
that.


-Hoss