In the following patch we plan to remove the base schema from the base_info
to make the base_info immutable. To do that, we first prepare the schema
registry for the change; we need to be able to create view schemas from
frozen schemas there and frozen schemas have no information about the base
table. Unless we do this change, after base schemas are removed from the
base info, we'll no longer be able to load a view schema to the schema registry
without looking up the base schema in the database.
This change also required some updates to schema building:
* we add a method for unfreezing a view schema with base info instead of
a base schema
* we make it possible to use schema_builder with a base info instead of
a base schema
* we add a method for creating a view schema from mutations with a base info
instead of a base schema
* we add a view_info constructor withat base info instead of a base schema
* we update the naming in schema_registry to reflect the usage of base info
instead of base schema
Currently, the base_info may or may not be set in view schemas.
Even when it's set, it may be modified. This necessitates extra
checks when handling view schemas, as well as potentially causing
errors when we forget to set it at some point.
Instead, we want to make the base info an immutable member of view
schemas (inside view_info). The first step towards that is making
sure that all newly created schemas have the base info set.
We achieve that by requiring a base schema when constructing a view
schema. Unfortunately, this adds complexity each time we're making
a view schema - we need to get the base schema as well.
In most cases, the base schema is already available. The most
problematic scenario is when we create a schema from mutations:
- when parsing system tables we can get the schema from the
database, as regular tables are parsed before views
- when loading a view schema using the schema loader tool, we need
to load the base additionally to the view schema, effectively
doubling the work
- when pulling the schema from another node - in this case we can
only get the current version of the base schema from the local
database
Additionally, we need to consider the base schema version - when
we generate view updates the version of the base schema used for
reads should match the version of the base schema in view's base
info.
This is achieved by selecting the correct (old or new) schema in
`db::schema_tables::merge_tables_and_views` and using the stored
base schema in the schema_registry.
Schema related files are moved there. This excludes schema files that
also interact with mutations, because the mutation module depends on
the schema. Those files will have to go into a separate module.
Closes#12858
Move mutation-related files to a new mutation/ directory. The names
are kept in the global namespace to reduce churn; the names are
unambiguous in any case.
mutation_reader remains in the readers/ module.
mutation_partition_v2.cc was missing from CMakeLists.txt; it's added in this
patch.
This is a step forward towards librarization or modularization of the
source base.
Closes#12788
A frozen schema can be quite large (in #10071 we measured 500 bytes per
column, and there can be thousands of columns in extreme tables). This
can cause large contiguous allocations and therefor memory stalls or
even failures to allocate.
Switch to bytes_ostream as the internal representation. Fortunately
frozen_schema is internally implemented as bytes_ostream, so the
change is minimal.
Ref #10071.
Test: unit (dev)
Closes#10105
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Eliminate not used includes and replace some more includes
with forward declarations where appropriate.
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
The header sits in many other headers, but there's a handy
schema_fwd.hh that's tiny and contains needed declarations
for other headers. So replace shema.hh with schema_fwd.hh
in most of the headers (and remove completely from some).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20200303102050.18462-1-xemul@scylladb.com>
Requires "workaround" fix for schema_registry and frozen_mutation, since
the former is a free-float thread local, and the latter is a pure data
carrier. frozen_schema can take a parameter for unfreeze, but schema
registry requires being told which the system extensions are.
