Current indexes on [sys_schema_change] has slow performance when table gets a large number of records which causes long page load times (KB0696762)

Description

Current indexes on [sys_schema_change] does not seem to be able to handle a large number of records, and can cause page to not load

Get [sys_schema_change] table to be large, mil+ for good measure
Upgrade an instance so that the upgrad monitor page has stats from the upgrade to display
Nav to upgrade monitor $upgrade_client.do

Page takes several minutes to load or can have the maximum execution time exceeded and not load.

Add the following index to speed things up: sys_schema_change(started, finished, duration)

Related Problem: PRB1255465

Seen In

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	SR - ITOM - Discovery and Service Mapping - v1.0.35
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	SR - SIR - Security Incident Response - Madrid 2019 Q2
	SR - SIR - Security Incident Response PA Content - New York 2019 Q3
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	SR - SIR - Store Threat Core - Madrid 2019 Q2
	SR - SIR - Store Trusted Security Circles Client - New York 2019 Q3
	SR - VR - Rapid7 - London 2019 Q2 v.6.2.1
	SR - VR - Vulnerability Response - New York 2019 Q3