Hi Julien,
Thanks for letting me know about promlens. Got to know the issue. Im so lame!!
To summarise:
my metric was defined as
metric(label1,label2,label3,label4) value
When label2 changed label4 was also changing
Hence, metric_total{label1="label1", label2="label2"} + ignoring(label2) metric_total(label2="label3") was not able to find a match (since both label2 and label4 changed but only label2 was ignored)
Fixed it by adding label4 to the ingoring list
metric_total{label1="label1", label2="label2"} + ignoring(label2,label4) metric_total(label2="label3")
Regards
Ankit