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built_indexes_virtual_reader.hh
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built_indexes_virtual_reader.hh
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/*
* Copyright (C) 2018-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#include "replica/database.hh"
#include "db/system_keyspace.hh"
#include "flat_mutation_reader_v2.hh"
#include "mutation_fragment_v2.hh"
#include "mutation_reader.hh"
#include "query-request.hh"
#include "schema_fwd.hh"
#include "secondary_index_manager.hh"
#include "tracing/tracing.hh"
#include "view_info.hh"
#include <memory>
namespace db::index {
class built_indexes_virtual_reader {
replica::database& _db;
struct built_indexes_reader : flat_mutation_reader_v2::impl {
replica::database& _db;
schema_ptr _schema;
query::partition_slice _view_names_slice;
flat_mutation_reader_v2 _underlying;
sstring _current_keyspace;
// Convert a key holding an index name (e.g., xyz) to a key holding
// the backing materialized-view name (e.g., xyz_index).
static clustering_key_prefix index_name_to_view_name(
const clustering_key_prefix& c,
const schema& built_views_schema,
const schema& built_indexes_schema)
{
sstring index_name = value_cast<sstring>(utf8_type->deserialize(*c.begin(built_indexes_schema)));
sstring view_name = ::secondary_index::index_table_name(index_name);
return clustering_key_prefix::from_single_value(built_views_schema, utf8_type->decompose(view_name));
}
// Convert a clustering_range holding a range of index names (e.g.,
// abc..xyz) to a range of backing view names (abc_index..xyz_index).
static query::clustering_range index_name_range_to_view_name_range(
const query::clustering_range& range,
const schema& built_views_schema,
const schema& built_indexes_schema)
{
bool singular = range.is_singular();
auto start = range.start();
auto end = range.end();
if (start) {
*start = query::clustering_range::bound(
index_name_to_view_name(start->value(), built_views_schema, built_indexes_schema),
start->is_inclusive());
}
if (end) {
*end = query::clustering_range::bound(
index_name_to_view_name(end->value(), built_views_schema, built_indexes_schema),
end->is_inclusive());
}
return query::clustering_range(std::move(start), std::move(end), singular);
}
// The index list reader is created with a slice of index names
// (e.g., xyz) but the underlying reader needs a slice of view names,
// e.g., xyz_index, so we need to add the _index suffix with
// index_table_name().
static query::partition_slice index_slice_to_view_slice(
const query::partition_slice& slice,
const schema& built_views_schema,
const schema& built_indexes_schema)
{
// Most of the slice - such as options and which columns to read -
// should be copied unchanged. Just the clustering row ranges need
// changing.
// Fix _row_ranges (used for WHERE specifying a clustering range):
query::partition_slice ret = slice;
for (query::clustering_range &range : ret._row_ranges) {
range = index_name_range_to_view_name_range(range, built_views_schema, built_indexes_schema);
}
// Fix _specific_ranges (used for continuing on paging).
auto& specific_ranges = ret.get_specific_ranges();
if (specific_ranges) {
partition_key pk = specific_ranges->pk();
std::vector<query::clustering_range> ranges;
for (const query::clustering_range &range : specific_ranges->ranges()) {
ranges.push_back(index_name_range_to_view_name_range(range, built_views_schema, built_indexes_schema));
}
ret.clear_ranges();
ret.set_range(built_indexes_schema, pk, ranges);
}
return ret;
}
built_indexes_reader(
replica::database& db,
schema_ptr schema,
reader_permit permit,
replica::column_family& built_views,
const dht::partition_range& range,
const query::partition_slice& slice,
const io_priority_class& pc,
tracing::trace_state_ptr trace_state,
streamed_mutation::forwarding fwd,
mutation_reader::forwarding fwd_mr)
: flat_mutation_reader_v2::impl(schema, permit)
, _db(db)
, _schema(std::move(schema))
, _view_names_slice(index_slice_to_view_slice(slice, *built_views.schema(), *_schema))
, _underlying(built_views.make_reader_v2(
built_views.schema(),
std::move(permit),
range,
_view_names_slice,
pc,
std::move(trace_state),
fwd,
fwd_mr)) {
}
bool is_index(const clustering_row& built_view_row) const {
auto view_name = value_cast<sstring>(utf8_type->deserialize(*built_view_row.key().begin(*_underlying.schema())));
try {
auto s = _db.find_schema(_current_keyspace, view_name);
return s->is_view() && _db.find_column_family(s->view_info()->base_id()).get_index_manager().is_index(view_ptr(s));
} catch (const replica::no_such_column_family&) {
return false;
}
}
virtual future<> fill_buffer() override {
return _underlying.fill_buffer().then([this] {
_end_of_stream = _underlying.is_end_of_stream();
while (!_underlying.is_buffer_empty()) {
auto mf = _underlying.pop_mutation_fragment();
if (mf.is_partition_start()) {
_current_keyspace = value_cast<sstring>(utf8_type->deserialize(*mf.as_partition_start().key().key().begin(*_underlying.schema())));
} else if (mf.is_clustering_row()) {
if (is_index(mf.as_clustering_row())) {
// mf's clustering key is the materialized view's
// name, xyz_index, while we need the index name
// xyz. So modify mf:
mf.mutate_as_clustering_row(*_underlying.schema(),
[&] (clustering_row& cr) mutable {
sstring view_name = value_cast<sstring>(utf8_type->deserialize(*cr.key().begin(*_underlying.schema())));
sstring index_name = ::secondary_index::index_name_from_table_name(view_name);
cr.key() = clustering_key_prefix::from_single_value(*_underlying.schema(), utf8_type->decompose(index_name));
});
} else {
continue;
}
}
push_mutation_fragment(std::move(mf));
}
});
}
virtual future<> next_partition() override {
_end_of_stream = false;
clear_buffer_to_next_partition();
if (is_buffer_empty()) {
return _underlying.next_partition();
}
return make_ready_future<>();
}
virtual future<> fast_forward_to(const dht::partition_range& pr) override {
clear_buffer();
_end_of_stream = false;
return _underlying.fast_forward_to(pr);
}
virtual future<> fast_forward_to(position_range range) override {
forward_buffer_to(range.start());
_end_of_stream = false;
// range contains index names (e.g., xyz) but the underlying table
// contains view names (e.g., xyz_index) so we need to add the
// _index suffix with index_table_name():
position_in_partition start = range.start();
position_in_partition end = range.end();
if (start.get_clustering_key_prefix()) {
clustering_key_prefix ck = index_name_to_view_name(
*start.get_clustering_key_prefix(),
*_underlying.schema(), *_schema);
start = position_in_partition(start.region(),
start.get_bound_weight(),
std::move(ck));
}
if (end.get_clustering_key_prefix()) {
clustering_key_prefix ck = index_name_to_view_name(
*end.get_clustering_key_prefix(),
*_underlying.schema(), *_schema);
start = position_in_partition(end.region(),
end.get_bound_weight(),
std::move(ck));
}
range = position_range(std::move(start), std::move(end));
return _underlying.fast_forward_to(std::move(range));
}
virtual future<> close() noexcept override {
return _underlying.close();
}
};
public:
built_indexes_virtual_reader(replica::database& db)
: _db(db) {
}
flat_mutation_reader_v2 operator()(
schema_ptr s,
reader_permit permit,
const dht::partition_range& range,
const query::partition_slice& slice,
const io_priority_class& pc,
tracing::trace_state_ptr trace_state,
streamed_mutation::forwarding fwd,
mutation_reader::forwarding fwd_mr) {
return make_flat_mutation_reader_v2<built_indexes_reader>(
_db,
std::move(s),
std::move(permit),
_db.find_column_family(s->ks_name(), system_keyspace::v3::BUILT_VIEWS),
range,
slice,
pc,
std::move(trace_state),
fwd,
fwd_mr);
}
};
}