1ec5688b0b
This patch fixes several cases where it was disallowed to create
a materialized view with a filter ("where ..."), for no good reason.
After this patch, these cases will be allowed. Fixes #2367.
In ordinary SELECT queries, certain types of filtering which is known to
be deceptively inefficient is now allowed. For example, trying to query
a range of partition keys cannot be done without reading the entire
database (because the murmur3 tokenizer randomizes the order of partitions).
Restricting two partition key components also cannot be done without
reading excessive amount of the entire partition. So Scylla, following
Cassandra, chooses to disallow such SELECT queries, and give an error
message.
However, the same SELECT statements *should* be allowed when defining a
materialized view. In this case, the filter is just used to check an
individual row - not to search for one - so there is no performance
concern.
Unfortunately the existing code did these validations while building the
SELECT statement's "restrictions", in code shared by both uses of SELECT
(query and MV definition). It was easy to move one of the validations
to later code which runs after the restriction has already been built (and
knows if it is working for query or MV), but because of the way the
"restrictions" objects (translated from Cassandra 2's code) hide what they
contain, many of the checks are harder to perform after having built the
restrictions object. So instead, we add in strategic places in the
restriction-handling code a new "allow_filtering" flag. If restrictions
are built with allow_filtering=true, the extra performance-oriented tests
on the filtering restrictions is not done. Materialized views sets
allow_filtering=true.
The allow_filtering flag will also be useful later when we want to support
the "ALLOW FILTERING" query option which is currently not supported properly
(we have several open issues on that). However note that this patch doesn't
complete that support: I left a FIXME in the spot where we set
allow_filtering in the Materialized Views case, but in the futre also need
to set it if the user specified "ALLOWED FILTERING" in the query.
This patch also enables several unit tests written by Duarte which used to
fail because of this bug, and now pass. These tests verify that the
restrictions are now allowed and filter the view as desired; But I also
added test code to verify that the same restrictions are still forbidden,
as before, when used in ordinary SELECT queries.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20180423124343.17591-1-nyh@scylladb.com>
105 lines
4.0 KiB
C++
105 lines
4.0 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Copyright (C) 2015 ScyllaDB
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*
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* Modified by 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 "cql3/statements/modification_statement.hh"
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#include "cql3/statements/raw/modification_statement.hh"
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#include "cql3/column_identifier.hh"
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#include "cql3/term.hh"
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#include "database_fwd.hh"
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#include <vector>
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#include "unimplemented.hh"
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namespace cql3 {
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namespace statements {
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/**
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* An <code>UPDATE</code> statement parsed from a CQL query statement.
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*
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*/
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class update_statement : public modification_statement {
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public:
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#if 0
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private static final Constants.Value EMPTY = new Constants.Value(ByteBufferUtil.EMPTY_BYTE_BUFFER);
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#endif
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update_statement(statement_type type, uint32_t bound_terms, schema_ptr s, std::unique_ptr<attributes> attrs, uint64_t* cql_stats_counter_ptr);
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private:
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virtual bool require_full_clustering_key() const override;
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virtual bool allow_clustering_key_slices() const override;
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virtual void add_update_for_key(mutation& m, const query::clustering_range& range, const update_parameters& params, const json_cache_opt& json_cache) override;
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virtual void execute_operations_for_key(mutation& m, const clustering_key_prefix& prefix, const update_parameters& params, const json_cache_opt& json_cache);
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};
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/*
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* Update statement specification that has specifically one bound name - a JSON string.
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* Overridden add_update_for_key uses this parsed JSON to look up values for columns.
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*/
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class insert_prepared_json_statement : public update_statement {
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::shared_ptr<term> _term;
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public:
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insert_prepared_json_statement(uint32_t bound_terms, schema_ptr s, std::unique_ptr<attributes> attrs, uint64_t* cql_stats_counter_ptr, ::shared_ptr<term> t)
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: update_statement(statement_type::INSERT, bound_terms, s, std::move(attrs), cql_stats_counter_ptr), _term(t) {
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_restrictions = ::make_shared<restrictions::statement_restrictions>(s, false);
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}
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private:
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virtual void execute_operations_for_key(mutation& m, const clustering_key_prefix& prefix, const update_parameters& params, const json_cache_opt& json_cache) override;
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virtual dht::partition_range_vector build_partition_keys(const query_options& options, const json_cache_opt& json_cache) override;
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virtual query::clustering_row_ranges create_clustering_ranges(const query_options& options, const json_cache_opt& json_cache) override;
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json_cache_opt maybe_prepare_json_cache(const query_options& options) override;
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void execute_set_value(mutation& m, const clustering_key_prefix& prefix, const update_parameters& params, const column_definition& column, const bytes_opt& value);
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};
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}
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}
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