Query hung. Any help. (sqlite dbi)
SQLite version 3.7.2 built on
This is perl, v5.8.8 built for x86_64-linux-thread-multi
DBI 1.611
DBD::SQLite 1.29
Centos Linux(2.6.18-164.11.1.el5xen) 64bit.
Below are output snippets from two dbi trace files. In the first snippet, the
sqlite.db is smallish,
Tilghman, Jack jack.tilgh...@navteq.com wrote:
sqlite trace: prepare statement: SELECT COUNT(*) FROM link LEFT OUTER JOIN
node ON node.pvid = link.ref_node_pvid WHERE
link.ref_node_pvid != -1 AND link.ref_node_pvid != -2 AND node.pvid IS
NULL;
Try this instead:
SELECT COUNT(*) FROM link
Thanks Igor, works great!
Btw, was there something incorrect about the way I had the query setup?
Thanks,
Jack
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Tilghman, Jack jack.tilgh...@navteq.com wrote:
Thanks Igor, works great!
Btw, was there something incorrect about the way I had the query setup?
Not incorrect, just wasteful. I suspect the query was spending a lot of time
working through rows where link and node do match up, only to throw
Nice Explanation Igor.
As it turns out, virtually all of the rows will match up as you correctly
suspected.
Thanks again.
Jack
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On Oct 18, 2010, at 6:58 PM, Igor Tandetnik wrote:
In general, I found that the idiom
TableA left join TableB on (TableA.idInTableB = TableB.someId) where
TableB.someId is null
almost always performs worse than the equivalent NOT EXISTS or NOT IN query.
Hmmm... in practice it should be
