BigTable GetRange

bigtable.go

tbl := client.Open("mytable")
...
unvKeyBeg, _, _ := ctx.UnversionedKey(tkBeg)
unvKeyEnd, _, _ := ctx.UnversionedKey(tkEnd)
rr := bigtable.NewRange(unvKeyBeg, unvKeyEnd)
err := tbl.ReadRows(bt_ctx, rr, func(r Row) bool {
    // get all versions from this row and package into "versions" which is []*storage.KeyValue
    ...
    // run it through our DAG to get the proper value given our version context.
    // See the code: https://github.com/janelia-flyem/dvid/blob/master/datastore/datainstance.go#L71
    kv, err := ctx.VersionedKeyValue(versions)
    return true // keep going
}, bigtable.RowFilter(bigtable.FamilyFilter("versions")))  // No filter necessary if we only have one column family
...

We could potentially refine ctx.VersionedKeyValue(versions) to accept a slice of struct that contains a versionID and value. If the column qualifiers are versionIDs, we don't need to decompose the full keys to get the versionID out.