[
https://issues.apache.org/jira/browse/HIVE-17051?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16076398#comment-16076398
]
Remus Rusanu commented on HIVE-17051:
-------------------------------------
This is a simple query
{noformat}
SELECT DISTINCT * FROM src;
{noformat}
If multiple tables are present (eg. JOIN) each table metadata is requested
twice.
> Each table metadata is requested twice during query compile
> -----------------------------------------------------------
>
> Key: HIVE-17051
> URL: https://issues.apache.org/jira/browse/HIVE-17051
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Reporter: Remus Rusanu
> Assignee: Remus Rusanu
> Labels: performance
>
> As far as I can tell, for each table referenced in a query the metadata is
> retrieved twice during compilation:
> first call:
> {noformat}
> at org.apache.hadoop.hive.ql.metadata.Hive.getTable(Hive.java:1320)
> at org.apache.hadoop.hive.ql.metadata.Hive.getTable(Hive.java:1275)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getTableObjectByName(SemanticAnalyzer.java:10943)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getMetaData(SemanticAnalyzer.java:1992)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getMetaData(SemanticAnalyzer.java:1942)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genResolvedParseTree(SemanticAnalyzer.java:11178)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:11309)
> at
> org.apache.hadoop.hive.ql.parse.CalcitePlanner.analyzeInternal(CalcitePlanner.java:295)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:261)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:566)
> {noformat}
> second call:
> {noformat}
> at org.apache.hadoop.hive.ql.metadata.Hive.getTable(Hive.java:1320)
> at org.apache.hadoop.hive.ql.metadata.Hive.getTable(Hive.java:1275)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getTableObjectByName(SemanticAnalyzer.java:10943)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getMetaData(SemanticAnalyzer.java:1992)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getMetaData(SemanticAnalyzer.java:1942)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.getMetaData(SemanticAnalyzer.java:1934)
> at
> org.apache.hadoop.hive.ql.parse.CalcitePlanner.genOPTree(CalcitePlanner.java:431)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:11320)
> at
> org.apache.hadoop.hive.ql.parse.CalcitePlanner.analyzeInternal(CalcitePlanner.java:295)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:261)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:566)
> {noformat}
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
