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https://issues.apache.org/jira/browse/DRILL-5089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942158#comment-15942158
]
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/795#discussion_r108051857
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/SchemaTreeProvider.java
---
@@ -119,6 +127,74 @@ public SchemaPlus createRootSchema(SchemaConfig
schemaConfig) {
}
}
+
+ public SchemaPlus createPartialRootSchema(final String userName, final
SchemaConfigInfoProvider provider,
+ final String storage) {
+ final String schemaUser = isImpersonationEnabled ? userName :
ImpersonationUtil.getProcessUserName();
+ final SchemaConfig schemaConfig = SchemaConfig.newBuilder(schemaUser,
provider).build();
+ final SchemaPlus rootSchema =
SimpleCalciteSchema.createRootSchema(false);
+ Set<String> storageSet = Sets.newHashSet();
+ storageSet.add(storage);
+ addNewStoragesToRootSchema(schemaConfig, rootSchema, storageSet);
+ schemaTreesToClose.add(rootSchema);
+ return rootSchema;
+ }
+
+ public SchemaPlus addPartialRootSchema(final String userName, final
SchemaConfigInfoProvider provider,
+ Set<String> storages,
SchemaPlus rootSchema) {
+ final String schemaUser = isImpersonationEnabled ? userName :
ImpersonationUtil.getProcessUserName();
+ final SchemaConfig schemaConfig = SchemaConfig.newBuilder(schemaUser,
provider).build();
+ addNewStoragesToRootSchema(schemaConfig, rootSchema, storages);
+ schemaTreesToClose.add(rootSchema);
+ return rootSchema;
+ }
+
+ private void expandSecondLevelSchema(SchemaPlus parent) {
--- End diff --
Maybe explain this a bit? Why are we expanding second-level schemas for
*all* top-level schemas? Can't we do the expansion on the fly as we resolve?
That is, if a query has a path "a.b.c.d", can't we just resolve a, then within
a, resolve b, and so on until we get to d? Else, we are still open to a
performance hit if, say, a is a directory of a million files, or a database
with 10K tables.
> 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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