A value in the range [0.0, 1.0] that represents the fraction
of rows assigned to this stream that have been processed by
the server. In the presence of read filters, the server may
process more rows than it returns, so this value reflects
progress through the pre-filtering rows. This value is only
populated for sessions created through the BALANCED sharding
strategy.
Whether this stream can be split. For sessions that use the
LIQUID sharding strategy, this value is always false. For
BALANCED sessions, this value is false when enough data have
been read such that no more splits are possible at that point
or beyond. For small tables or streams that are the result of
a chain of splits, this value may never be true.
