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From: Peter Eisentraut <peter_e@gmx.net>
To: rhdb-explain@sources.redhat.com
Subject: Crash with PostgreSQL 7.4
Date: Wed, 25 Feb 2004 23:30:00 -0000
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I have used rhdb-explain from the tag RHDB-3-0 and ran the following
query against an empty PostgreSQL 7.4.1 database:

select * from pg_tables;

This causes a null pointer exception.  The output on the console is

java.lang.NullPointerException
        at com.redhat.rhdb.explain.ExplainParserV73.addQual(ExplainParserV73.java:796)
        at com.redhat.rhdb.explain.ExplainParserV73.buildExplainTree(ExplainParserV73.java:343)
        at com.redhat.rhdb.explain.ExplainParserV73.explain(ExplainParserV73.java:187)
        at com.redhat.rhdb.explain.Explain$ExplainThread.run(Explain.java:298)

The reason is that the parser code only knows "Hash Join" but PG 7.4
emits a "Hash Left Join" in this case.

Attached is a patch that kind of papers over this issue by ignoring
"Left" and other possible hash-join attributes.  Eventually one might
want to show this distinction to the user.

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*** ../src/rhdb/guitools/rhdb-explain/src/com/redhat/rhdb/explain/ExplainParserV73.java	2003-11-21 19:30:47.000000000 +0100
--- src/com/redhat/rhdb/explain/ExplainParserV73.java	2004-02-25 21:06:04.000000000 +0100
***************
*** 447,452 ****
--- 447,460 ----
  			{
  				String next = strtok.nextToken();
  
+ 				if (next.equals("Left")
+ 				    || next.equals("Right")
+ 				    || next.equals("Full")
+ 				    || next.equals("IN"))
+ 				{
+ 					next = strtok.nextToken();
+ 				}
+ 
  				if (next.equals("Join"))
  				{
  					node.setType(ExplainTreeNode.NODE_JOIN);

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