Bug 1388421

Summary: Remove connection check before each query
Product: [oVirt] ovirt-engine Reporter: Eli Mesika <emesika>
Component: Database.DALAssignee: Oved Ourfali <oourfali>
Status: CLOSED CURRENTRELEASE QA Contact: Lucie Leistnerova <lleistne>
Severity: high Docs Contact:
Priority: unspecified    
Version: 4.0.0CC: bugs, gklein, mperina, oourfali
Target Milestone: ovirt-4.1.0-alphaFlags: rule-engine: ovirt-4.1+
rule-engine: planning_ack+
mperina: devel_ack+
pstehlik: testing_ack+
Target Release: 4.1.0   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-02-01 14:57:18 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: Infra RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1388462    

Description Eli Mesika 2016-10-25 10:19:50 UTC 
Description of problem:
Currently, each time a connection is requested from the connection pool, the connection is tested by selecting a "select 1;" query to the database.

This is redundant, since still the query can fail after it was checked.
In addition we should rely on the connection pool itself to give us a "good connection" 

This "select 1;" is harming database performance since every query executed is actually 2 queries resulting in 2 round-trips to the database to get the results.


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.Track JDBC queries with JBuilder or any other tool that do the same
2.See that the top most executed query is "select 1;"
3.

Actual results:

"select 1;" is performed before any query to the database to test the connection.


Expected results:
We should rely on connection pooling and exception handling for getting a good connection and handling the exception in case that the connection fails to perform the query 

Additional info:
Comment 1 Red Hat Bugzilla Rules Engine 2016-10-25 10:21:22 UTC 
Target release should be placed once a package build is known to fix a issue. Since this bug is not modified, the target version has been reset. Please use target milestone to plan a fix for a oVirt release.
Comment 2 Red Hat Bugzilla Rules Engine 2016-10-25 10:23:29 UTC 
Bug tickets must have version flags set prior to targeting them to a release. Please ask maintainer to set the correct version flags and only then set the target milestone.
Comment 3 Sandro Bonazzola 2016-12-12 14:01:35 UTC 
The fix for this issue should be included in oVirt 4.1.0 beta 1 released on December 1st. If not included please move back to modified.
Comment 4 Lucie Leistnerova 2017-01-17 12:45:27 UTC 
'select 1' in 10s goes from 60 to 2 occurrences

verified in ovirt-engine-
4.1.0-0.4.master.20170116141310.gita30debd.el7.centos.noarch