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https://issues.apache.org/jira/browse/DRILL-5089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16250408#comment-16250408
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ASF GitHub Bot commented on DRILL-5089:
---------------------------------------

Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/1032#discussion_r150686157
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/store/dfs/WorkspaceSchemaFactory.java
 ---
    @@ -532,7 +572,10 @@ public boolean isMutable() {
         }
     
         public DrillFileSystem getFS() {
    -      return fs;
    +      if (this.fs == null) {
    +        this.fs = 
ImpersonationUtil.createFileSystem(schemaConfig.getUserName(), fsConf);
    +      }
    +      return this.fs;
    --- End diff --
    
    This class caches the file system, which is good. The other classes in this 
PR do not; they create the fs as needed.
    
    Does Calcite allow some kind of session state in which we can cache the fs 
for the query (plan) rather than creating it on the fly each time we need it?


> Skip initializing all enabled storage plugins for every query
> -------------------------------------------------------------
>
>                 Key: DRILL-5089
>                 URL: https://issues.apache.org/jira/browse/DRILL-5089
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Query Planning & Optimization
>    Affects Versions: 1.9.0
>            Reporter: Abhishek Girish
>            Assignee: Chunhui Shi
>            Priority: Critical
>
> In a query's lifecycle, at attempt is made to initialize each enabled storage 
> plugin, while building the schema tree. This is done regardless of the actual 
> plugins involved within a query. 
> Sometimes, when one or more of the enabled storage plugins have issues - 
> either due to misconfiguration or the underlying datasource being slow or 
> being down, the overall query time taken increases drastically. Most likely 
> due the attempt being made to register schemas from a faulty plugin.
> For example, when a jdbc plugin is configured with SQL Server, and at one 
> point the underlying SQL Server db goes down, any Drill query starting to 
> execute at that point and beyond begin to slow down drastically. 
> We must skip registering unrelated schemas (& workspaces) for a query. 



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