Switch from table to tag based metrics

[jpkrohling]

Context: #776 (comment)

Some metrics are created as tables, like:

casMetrics.NewTable(metricsFactory, "traces")

We need to investigate if simple tag based metrics wouldn't be sufficient for this case.

[yurishkuro]

The point was that instead of creating these metrics with a namespace

func NewTable(factory metrics.Factory, tableName string) *Table {
	t := storageMetrics.WriteMetrics{}
	metrics.Init(&t, factory.Namespace(tableName, nil), nil)
	return &Table{t}
}

we put the table name in the tag instead:

func NewTable(factory metrics.Factory, tableName string) *Table {
	t := storageMetrics.WriteMetrics{}
	// metrics.Init(&t, factory.Namespace(tableName, nil), nil)
	metrics.Init(&t, factory.Namespace("", map[string]string{"table", tableName}), nil)
	return &Table{t}
}

[jpkrohling]

I'm closing this then, as you were faster :)