union 
workspace(""workspace1"").InsightsMetrics,
workspace(""workspace2"").InsightsMetrics,
workspace(""workspace3"").InsightsMetrics,
workspace(""workspace4"").InsightsMetrics,
workspace(""workspace5"").InsightsMetrics,
workspace(""workspace6"").InsightsMetrics
| where TimeGenerated > ago(30d)
| where Origin == "vm.azm.ms" and Namespace == "Memory"
| extend TotalMemoryGB=(todynamic(Tags)["vm.azm.ms/memorySizeMB"])/(1024)
| summarize AvailableMemoryGB = round(avg(Val)/(1024),2) by Computer, TotalMemoryGB, _ResourceId
| extend Availabile_Memory_Percentage= round((AvailableMemoryGB/TotalMemoryGB)*100, 2)
| project Computer, TotalMemoryGB, AvailableMemoryGB,Availabile_Memory_Percentage

The query omits data from the last 7 days (not sure why). The table has retention of 30 days.I am pulling the data from the InsightsMetrics table. How do i troubleshoot? And can i make the query more efficient? Appreciate feedback