I was suffering from similar issue for SQL server for different databases. Below are the details.
Cloud Environment: Sitecore Managed Cloud XP-Small and XP-Medium
Sitecore Version: Sitecore 9.1 update 1.
Cause of the issue: By default from Sitecore Managed Cloud Team indexing strategy was set to "onPublishEndAsyncSingleInstance" in CD role.
After investigating 10 days with Sitecore support and Product services team we found that indexing strategy was set to "onPublishEndAsyncSingleInstance" which was causing excessive DTU usage. This was set for below.
- sitecore_web_index
- sitecore_fxm_web_index
- sitecore_marketing_asset_index_web
- sitecore_marketingdefinitions_web
Solution: Apart from the Patch which is mentioned in comment by Wesley Lomax, We created a patch file for setting indexing strategy to Manual for all above from CD role. As all these are getting rebuild properly from CM role.
Patch file: Patch file has below configurations. Note this has to be added only on CD role.
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
<sitecore>
<contentSearch>
<configuration>
<indexes>
<index id="sitecore_web_index">
<strategies>
<strategy>
<patch:delete />
</strategy>
<strategy ref="contentSearch/indexConfigurations/indexUpdateStrategies/manual" />
</strategies>
</index>
<index id="sitecore_fxm_web_index">
<strategies>
<strategy>
<patch:delete />
</strategy>
<strategy ref="contentSearch/indexConfigurations/indexUpdateStrategies/manual" />
</strategies>
</index>
<index id="sitecore_marketing_asset_index_web">
<strategies>
<strategy>
<patch:delete />
</strategy>
<strategy ref="contentSearch/indexConfigurations/indexUpdateStrategies/manual" />
</strategies>
</index>
<index id="sitecore_marketingdefinitions_web">
<strategies>
<strategy>
<patch:delete />
</strategy>
<strategy ref="contentSearch/indexConfigurations/indexUpdateStrategies/manual" />
</strategies>
</index>
</indexes>
</configuration>
</contentSearch>
</sitecore>
</configuration>
Additional changes: We added local cache setting to Azure apps.
Hope this answer will help you.