ineffective inner join with more null values
--------------------------------------------
Key: CORE-4531
URL: http://tracker.firebirdsql.org/browse/CORE-4531
Project: Firebird Core
Issue Type: Improvement
Components: Engine
Affects Versions: 3.0 Alpha 2
Reporter: Alex Bekhtin
select count(*) from MS2008_TABLES_FIELDS F1
inner join MS2008_TABLES_FIELDS F2 on F1.defname = F2.defname
COUNT
76071
------ Performance info ------
Prepare time = 0ms
Execute time = 15s 538ms
Avg fetch time = 15 538,00 ms
Current memory = 557 312 224
Max memory = 557 647 744
Memory buffers = 32 768
Reads from disk to cache = 0
Writes from cache to disk = 0
Fetches from cache = 606 267
select count(*) from MS2008_TABLES_FIELDS F1
inner join MS2008_TABLES_FIELDS F2 on F1.defname = F2.defname
where f1.defname is NOT NULL
COUNT
76071
------ Performance info ------
Prepare time = 15ms
Execute time = 265ms
Avg fetch time = 265,00 ms
Current memory = 557 315 736
Max memory = 557 647 744
Memory buffers = 32 768
Reads from disk to cache = 0
Writes from cache to disk = 0
Fetches from cache = 257 217
--------------------------------------------------
CREATE TABLE MS2008_TABLES_FIELDS (
...
DEFNAME VARCHAR(128),
...
);
CREATE INDEX MS2008_TABLES_FIELDS_IDX4 ON MS2008_TABLES_FIELDS (DEFNAME);
select count(*) from MS2008_TABLES_FIELDS F1
---
COUNT
41682
select count(*) from MS2008_TABLES_FIELDS F1 where F1.defname is not null
---
COUNT
6777
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://tracker.firebirdsql.org/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
------------------------------------------------------------------------------
Slashdot TV.
Video for Nerds. Stuff that matters.
http://tv.slashdot.org/
Firebird-Devel mailing list, web interface at
https://lists.sourceforge.net/lists/listinfo/firebird-devel
