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We keep track of all updates and store the minimal values of timestamps, TTLs and local deletion times across all the inserted data. These values are written as a part of serialization_header for Statistics.db and used for delta-encoding values when writing Data.db file in SSTables 3.0 (mc) format. For #1969. Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
42 lines
1.5 KiB
C++
42 lines
1.5 KiB
C++
/*
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* Copyright (C) 2018 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 "timestamp.hh"
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// Stores statistics on all the updates done to a memtable
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// The collected statistics is used for flushing memtable to the disk
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struct encoding_stats {
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// The fixed epoch corresponds to 2018-03-22, 00:00:00 GMT-0.
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// Encoding stats are used for delta-encoding, so we want some default values
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// that are just good enough so we take some recent date in the past
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static constexpr uint32_t deletion_time_epoch = 1521676800;
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static constexpr api::timestamp_type timestamp_epoch = deletion_time_epoch * 1000 * 1000;
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static constexpr uint32_t ttl_epoch = 0;
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api::timestamp_type min_timestamp = timestamp_epoch;
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uint32_t min_local_deletion_time = deletion_time_epoch;
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uint32_t min_ttl = ttl_epoch;
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};
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