This is a bug in the graphical explain plan in the pgAdmin III Query
tool. In the graphical explain plan if your query is ordering with the
help of an index and the order is "Descending" then the graphical
explain plan just says "using" as the index name. If the sort order is
ascending then the correct index name is displayed. Here are the
relevant lines from the textual output from explain:
DESC -> Index Scan Backward using idx_name on table_name
ASC -> Index Scan using idx_name on table_name
This may be because the code for getting the index name is grabbing the
4th word and does not check to see if the word "Backward" was added to
the line, in which case the 5th word should be used.
My Environment:
pgAdmin III 1.4.3
Default config, downloaded precomplied binary for windows
Windows XP
Postgresql 8.1.4
To reproduce the problem is simple, just be sure to order by an indexed
column and then click the Explain Query button:
select * from table_name order by indexed_col asc limit 1
select * from table_name order by indexed_col desc limit 1
I did a mailing list search but didn't see anyone else reporting this.
If it's a newly found bug then I'd greatly appreciate it if someone
could fix this. I use the graphical query explain tool a lot, I find it
to be very useful when designing new queries.
Thanks,
Brendan
