We want the format of query results to be eventually defined in the
IDL and be independent of the format we use in memory to represent
collections. This change is a step in this direction.
The change decouples format of collection cells in query results from
our in-memory representation. We currently use collection_mutation_view,
after the change we will use CQL binary protocol format. We use that because
it requires less transformations on the coordinator side.
One complication is that some list operations need to retrieve keys
used in list cells, not only values. To satisfy this need, new query
option was added called "collections_as_maps" which will cause lists
and sets to be reinterpreted as maps matching their underlying
representation. This allows the coordinator to generate mutations
referencing existing items in lists.
We use boost::any to convert to and from database values (stored in
serlialized form) and native C++ values. boost::any captures information
about the data type (how to copy/move/delete etc.) and stores it inside
the boost::any instance. We later retrieve the real value using
boost::any_cast.
However, data_value (which has a boost::any member) already has type
information as a data_type instance. By teaching data_type intances about
the corresponding native type, we can elimiante the use of boost::any.
While boost::any is evil and eliminating it improves efficiency somewhat,
the real goal is growing native type support in data_type. We will use that
later to store native types in the cache, enabling O(log n) access to
collections, O(1) access to tuples, and more efficient large blob support.
Collection cells in query results are serialized using the "mutation form",
and must be deserialized using that format as well.
Fixes "--logger-log-level storage_proxy=trace" crasher.
This builder is the one used to build the convenient result_set (not
on fast path). The builder was assuming that the whole set of columns
was always queried, which resulted in buffer underflow exceptions
during parsing of the results if this was not the case. Let's also
handle queries which have narrower column sets.
Add a query::result_set class that contains per-row cells that can be
accessed by column name. Partition keys, clustering keys, and static
values are duplicated for every row for convenience.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
