[SOLR-4910] solr.xml persistence is completely broken

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 4.4, 6.0
• Fix Version/s: 4.4, 6.0
• Assignee: Erick Erickson
• Reporter: Erick Erickson
• Created: 07/Jun/13 22:50
• Updated: 09/May/16 18:57
• Resolved: 17/Jun/13 01:36

Description

I'm working on SOLR-4862 (persisting a created core doesn't preserve some values) and at least compared to 4.3 code, persisting to solr.xml is completely broken.

I learned to hate persistence while working on SOLR-4196 & etc. and I'm glad it's going away. I frequently got lost in implicit properties (they're easy to persist and shouldn't be), what should/shouldn't be persisted (e.g. the translated ${var:default} or the original), and it was a monster, so don't think I'm nostalgic for the historical behavior.

Before I dive back in I want to get some idea whether or not the current behavior was intentional or not, I don't want to go back into that junk only to undo someone else's work.

Creating a new core (collection2 in my example) with persistence turned on in solr.xml for instance changes the original definition for collection1 (stock 4.x as of tonight) from this:

<core name="collection1" instanceDir="collection1" shard="${shard:}" collection="${collection:collection1}" config="${solrconfig:solrconfig.xml}" schema="${schema:schema.xml}"
coreNodeName="${coreNodeName:}"/>
to this:

<core loadOnStartup="true" shard="${shard:}" instanceDir="collection1/" transient="false" name="collection1" dataDir="data/" collection="${collection:collection1}">
<property name="name" value="collection1"/>
<property name="config" value="solrconfig.xml"/>
<property name="solr.core.instanceDir" value="solr/collection1/"/>
<property name="transient" value="false"/>
<property name="schema" value="schema.xml"/>
<property name="loadOnStartup" value="true"/>
<property name="solr.core.schemaName" value="schema.xml"/>
<property name="solr.core.name" value="collection1"/>
<property name="solr.core.dataDir" value="data/"/>
<property name="instanceDir" value="collection1/"/>
<property name="solr.core.configName" value="solrconfig.xml"/>
</core>

So, there are two questions:
1> what is correct for 4.x?
2> do we care at all about 5.x?

As much as I hate to say it, I think that we need to go back to the 4.3 behavior. It might be as simple as not persisting in the <property> tags anything already in the original definition. Not quite sure what to put where in the newly-created core though, I suspect that the compact <core + attribs> would be best (assuming there's no <property> tag already in the definition. I really hate the mix of attributes on the <core> tag and <property> tags, wish we had one or the other....

Issue Links

• contains: SOLR-4852 If sharedLib is set to lib, classloader fails to find classes in lib
• contains: SOLR-4850 Cores defined as loadOnStartup="true" and transient="true" can't be queried
• contains: SOLR-3900 LogWatcher Config Not Persisted
• contains: SOLR-4363 Inconsistent "coreLoadThreads" attributes in solr.xml between read/write
• contains: SOLR-4862 Core admin action "CREATE" fails to persist some settings in solr.xml
• contains: SOLR-5051 CoreAdmin API does not handle config and schema parameters when persistence is enabled
• relates to: SOLR-4932 Persisting solr.xml still adds some elements that aren't in the original
• relates to: SOLR-4914 Factor out core discovery and persistence logic