db03295c8a
"Currently data query digest includes cells and tombstones which may have expired or be covered by higher-level tombstones. This causes digest mismatch between replicas if some elements are compacted on one of the nodes and not on others. This mismatch triggers read-repair which doesn't resolve because mutations received by mutation queries are not differing, they are compacted already. The fix adds compacting step before writing and digesting query results by reusing the algorithm used by mutation query. This is not the most optimal way to fix this. The compaction step could be folded with the query writing, there is redundancy in both steps. However such change carries more risk, and thus was postponed. perf_simple_query test (cassandra-stress-like partitions) shows regression from 83k to 77k (7%) ops/s. Fixes #1165."
140 lines
4.3 KiB
C++
140 lines
4.3 KiB
C++
/*
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* Copyright (C) 2015 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "query-request.hh"
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#include "query-result.hh"
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#include "mutation_reader.hh"
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#include "frozen_mutation.hh"
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class reconcilable_result;
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class frozen_reconcilable_result;
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// Can be read by other cores after publishing.
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struct partition {
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uint32_t _row_count;
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frozen_mutation _m; // FIXME: We don't need cf UUID, which frozen_mutation includes.
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partition(uint32_t row_count, frozen_mutation m)
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: _row_count(row_count)
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, _m(std::move(m))
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{ }
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uint32_t row_count() const {
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return _row_count;
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}
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const frozen_mutation& mut() const {
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return _m;
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}
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frozen_mutation& mut() {
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return _m;
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}
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bool operator==(const partition& other) const {
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return _row_count == other._row_count && _m.representation() == other._m.representation();
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}
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bool operator!=(const partition& other) const {
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return !(*this == other);
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}
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};
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// The partitions held by this object are ordered according to dht::decorated_key ordering and non-overlapping.
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// Each mutation must have different key.
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//
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// Can be read by other cores after publishing.
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class reconcilable_result {
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uint32_t _row_count;
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std::vector<partition> _partitions;
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public:
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~reconcilable_result();
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reconcilable_result();
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reconcilable_result(reconcilable_result&&) = default;
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reconcilable_result& operator=(reconcilable_result&&) = default;
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reconcilable_result(uint32_t row_count, std::vector<partition> partitions);
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const std::vector<partition>& partitions() const;
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std::vector<partition>& partitions();
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uint32_t row_count() const {
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return _row_count;
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}
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bool operator==(const reconcilable_result& other) const;
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bool operator!=(const reconcilable_result& other) const;
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struct printer {
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const reconcilable_result& self;
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schema_ptr schema;
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friend std::ostream& operator<<(std::ostream&, const printer&);
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};
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printer pretty_printer(schema_ptr) const;
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};
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query::result to_data_query_result(const reconcilable_result&, schema_ptr, const query::partition_slice&);
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// Performs a query on given data source returning data in reconcilable form.
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//
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// Reads at most row_limit rows. If less rows are returned, the data source
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// didn't have more live data satisfying the query.
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//
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// Any cells which have expired according to query_time are returned as
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// deleted cells and do not count towards live data. The mutations are
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// compact, meaning that any cell which is covered by higher-level tombstone
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// is absent in the results.
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//
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// 'source' doesn't have to survive deferring.
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future<reconcilable_result> mutation_query(
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schema_ptr,
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const mutation_source& source,
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const query::partition_range& range,
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const query::partition_slice& slice,
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uint32_t row_limit,
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gc_clock::time_point query_time);
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class querying_reader {
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schema_ptr _schema;
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const query::partition_range& _range;
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const query::partition_slice& _slice;
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uint32_t _requested_limit;
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gc_clock::time_point _query_time;
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uint32_t _limit;
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const mutation_source& _source;
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std::function<void(uint32_t, mutation&&)> _consumer;
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std::experimental::optional<mutation_reader> _reader;
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public:
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querying_reader(schema_ptr s,
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const mutation_source& source,
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const query::partition_range& range,
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const query::partition_slice& slice,
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uint32_t row_limit,
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gc_clock::time_point query_time,
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std::function<void(uint32_t, mutation&&)> consumer);
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future<> read();
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};
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