30f721afab
When a view's partition key contains only columns from the base's partition key (and not an additional one), the liveness (existance or disappearance) of a view-table row is tied to the liveness of the base table row - and that depends not only on selected columns (base-table columns SELECTed to also appear in the view) but also on unselected columns. This means that we may need to keep a view row alive even without data, just because some unselected column is alive in the base table. Before this patch we tried to build a single "row marker" in the view column which summarizes the liveness information in all unselected columns, but this proved unworkable, as explained in issue #3362 and as will be demonstrated in unit tests in a later patch. Because we can't replace several unselected cells by one row marker, what we do in this patch is to add for each for the unselected cell a "virtual cell" which contains the cell's liveness information (timestamp, deletion, ttl) but not its value. For collections, we can't represent the entire collection by one virtual cell, and rather need a collection of virtual cells. This patch just adds the virtual columns to the view schema. Code in the previous patch, when it notices the virtual columns in the view's schema, added the appropriate content into these columns. We may need to add virtual columns to a view when first created, but also when an unselected column is added to the base table with "ALTER TABLE", so both are supported in this patch. Fixes #3362. Signed-off-by: Nadav Har'El <nyh@scylladb.com>
125 lines
4.9 KiB
C++
125 lines
4.9 KiB
C++
/*
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* Copyright (C) 2016 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 "service/storage_proxy_stats.hh"
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#include "dht/i_partitioner.hh"
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#include "gc_clock.hh"
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#include "query-request.hh"
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#include "schema.hh"
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#include "mutation_fragment.hh"
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#include "flat_mutation_reader.hh"
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#include "stdx.hh"
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namespace db {
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namespace view {
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struct stats : public service::storage_proxy_stats::write_stats {
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int64_t view_updates_pushed_local = 0;
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int64_t view_updates_pushed_remote = 0;
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int64_t view_updates_failed_local = 0;
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int64_t view_updates_failed_remote = 0;
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stats(const sstring& category) : service::storage_proxy_stats::write_stats(category, false) { }
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};
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/**
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* Whether the view filter considers the specified partition key.
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*
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* @param base the base table schema.
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* @param view_info the view info.
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* @param key the partition key that is updated.
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* @return false if we can guarantee that inserting an update for specified key
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* won't affect the view in any way, true otherwise.
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*/
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bool partition_key_matches(const schema& base, const view_info& view, const dht::decorated_key& key);
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/**
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* Whether the view might be affected by the provided update.
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*
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* Note that having this method return true is not an absolute guarantee that the view will be
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* updated, just that it most likely will, but a false return guarantees it won't be affected.
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*
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* @param base the base table schema.
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* @param view_info the view info.
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* @param key the partition key that is updated.
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* @param update the base table update being applied.
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* @return false if we can guarantee that inserting update for key
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* won't affect the view in any way, true otherwise.
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*/
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bool may_be_affected_by(const schema& base, const view_info& view, const dht::decorated_key& key, const rows_entry& update);
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/**
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* Whether a given base row matches the view filter (and thus if the view should have a corresponding entry).
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*
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* Note that this differs from may_be_affected_by in that the provide row must be the current
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* state of the base row, not just some updates to it. This function also has no false positive: a base
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* row either does or doesn't match the view filter.
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*
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* Also note that this function doesn't check the partition key, as it assumes the upper layers
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* have already filtered out the views that are not affected.
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*
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* @param base the base table schema.
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* @param view_info the view info.
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* @param key the partition key that is updated.
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* @param update the current state of a particular base row.
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* @param now the current time in seconds (to decide what is live and what isn't).
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* @return whether the base row matches the view filter.
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*/
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bool matches_view_filter(const schema& base, const view_info& view, const partition_key& key, const clustering_row& update, gc_clock::time_point now);
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bool clustering_prefix_matches(const schema& base, const partition_key& key, const clustering_key_prefix& ck);
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future<std::vector<mutation>> generate_view_updates(
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const schema_ptr& base,
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std::vector<view_ptr>&& views_to_update,
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flat_mutation_reader&& updates,
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flat_mutation_reader_opt&& existings);
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query::clustering_row_ranges calculate_affected_clustering_ranges(
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const schema& base,
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const dht::decorated_key& key,
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const mutation_partition& mp,
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const std::vector<view_ptr>& views);
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future<> mutate_MV(const dht::token& base_token, std::vector<mutation> mutations, db::view::stats& stats);
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/**
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* create_virtual_column() adds a "virtual column" to a schema builder.
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* The definition of a "virtual column" is based on the given definition
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* of a regular column, except that any value types are replaced by the
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* empty type - and only the information needed to track column liveness
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* is kept: timestamp, deletion, ttl, and keys in maps.
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* In some cases we add such virtual columns for unselected columns in
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* materialized views, for reasons explained in issue #3362.
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* @param builder the schema_builder where we want to add the virtual column.
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* @param name the name of the virtual column to be created.
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* @param type of the base column for which we want to build a virtual column.
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* When type is a multi-cell collection, so will be the virtual column.
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*/
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void create_virtual_column(schema_builder& builder, const bytes& name, const data_type& type);
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}
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}
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