ClickHouse/dbms/include/DB/Dictionaries/ClickHouseDictionarySource.h

242 lines
6.2 KiB
C++

#pragma once
#include <DB/Dictionaries/IDictionarySource.h>
#include <DB/Client/ConnectionPool.h>
#include <DB/DataStreams/RemoteBlockInputStream.h>
#include <DB/Interpreters/executeQuery.h>
#include <DB/Common/isLocalAddress.h>
#include <ext/range.hpp>
#include <Poco/Util/AbstractConfiguration.h>
#include "writeParenthesisedString.h"
namespace DB
{
const auto max_connections = 16;
/** Allows loading dictionaries from local or remote ClickHouse instance
* @todo use ConnectionPoolWithFailover
* @todo invent a way to keep track of source modifications
*/
class ClickHouseDictionarySource final : public IDictionarySource
{
public:
ClickHouseDictionarySource(const DictionaryStructure & dict_struct,
const Poco::Util::AbstractConfiguration & config,
const std::string & config_prefix,
const Block & sample_block, Context & context)
: dict_struct{dict_struct},
host{config.getString(config_prefix + ".host")},
port(config.getInt(config_prefix + ".port")),
user{config.getString(config_prefix + ".user", "")},
password{config.getString(config_prefix + ".password", "")},
db{config.getString(config_prefix + ".db", "")},
table{config.getString(config_prefix + ".table")},
where{config.getString(config_prefix + ".where", "")},
sample_block{sample_block}, context(context),
is_local{isLocalAddress({ host, port })},
pool{is_local ? nullptr : std::make_unique<ConnectionPool>(
max_connections, host, port, db, user, password,
"ClickHouseDictionarySource")
},
load_all_query{composeLoadAllQuery()}
{}
/// copy-constructor is provided in order to support cloneability
ClickHouseDictionarySource(const ClickHouseDictionarySource & other)
: dict_struct{other.dict_struct},
host{other.host}, port{other.port}, user{other.user}, password{other.password},
db{other.db}, table{other.table},
where{other.where},
sample_block{other.sample_block}, context(other.context),
is_local{other.is_local},
pool{is_local ? nullptr : std::make_unique<ConnectionPool>(
max_connections, host, port, db, user, password,
"ClickHouseDictionarySource")},
load_all_query{other.load_all_query}
{}
BlockInputStreamPtr loadAll() override
{
/** Query to local ClickHouse is marked internal in order to avoid
* the necessity of holding process_list_element shared pointer.
*/
if (is_local)
return executeQuery(load_all_query, context, true).in;
return new RemoteBlockInputStream{pool.get(), load_all_query, nullptr};
}
BlockInputStreamPtr loadIds(const std::vector<std::uint64_t> & ids) override
{
const auto query = composeLoadIdsQuery(ids);
if (is_local)
return executeQuery(query, context, true).in;
return new RemoteBlockInputStream{pool.get(), query, nullptr};
}
bool isModified() const override { return true; }
bool supportsSelectiveLoad() const override { return true; }
DictionarySourcePtr clone() const override { return std::make_unique<ClickHouseDictionarySource>(*this); }
std::string toString() const override
{
return "ClickHouse: " + db + '.' + table + (where.empty() ? "" : ", where: " + where);
}
private:
std::string composeLoadAllQuery() const
{
std::string query;
{
WriteBufferFromString out{query};
writeString("SELECT ", out);
if (!dict_struct.id.expression.empty())
{
writeParenthesisedString(dict_struct.id.expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(dict_struct.id.name, out);
if (dict_struct.range_min && dict_struct.range_max)
{
writeString(", ", out);
if (!dict_struct.range_min->expression.empty())
{
writeParenthesisedString(dict_struct.range_min->expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(dict_struct.range_min->name, out);
writeString(", ", out);
if (!dict_struct.range_max->expression.empty())
{
writeParenthesisedString(dict_struct.range_max->expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(dict_struct.range_max->name, out);
}
for (const auto & attr : dict_struct.attributes)
{
writeString(", ", out);
if (!attr.expression.empty())
{
writeParenthesisedString(attr.expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(attr.name, out);
}
writeString(" FROM ", out);
if (!db.empty())
{
writeProbablyBackQuotedString(db, out);
writeChar('.', out);
}
writeProbablyBackQuotedString(table, out);
if (!where.empty())
{
writeString(" WHERE ", out);
writeString(where, out);
}
writeChar(';', out);
}
return query;
}
std::string composeLoadIdsQuery(const std::vector<std::uint64_t> ids)
{
std::string query;
{
WriteBufferFromString out{query};
writeString("SELECT ", out);
if (!dict_struct.id.expression.empty())
{
writeParenthesisedString(dict_struct.id.expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(dict_struct.id.name, out);
for (const auto & attr : dict_struct.attributes)
{
writeString(", ", out);
if (!attr.expression.empty())
{
writeParenthesisedString(attr.expression, out);
writeString(" AS ", out);
}
writeProbablyBackQuotedString(attr.name, out);
}
writeString(" FROM ", out);
if (!db.empty())
{
writeProbablyBackQuotedString(db, out);
writeChar('.', out);
}
writeProbablyBackQuotedString(table, out);
writeString(" WHERE ", out);
if (!where.empty())
{
writeString(where, out);
writeString(" AND ", out);
}
writeProbablyBackQuotedString(dict_struct.id.name, out);
writeString(" IN (", out);
auto first = true;
for (const auto id : ids)
{
if (!first)
writeString(", ", out);
first = false;
writeString(DB::toString(id), out);
}
writeString(");", out);
}
return query;
}
const DictionaryStructure dict_struct;
const std::string host;
const UInt16 port;
const std::string user;
const std::string password;
const std::string db;
const std::string table;
const std::string where;
Block sample_block;
Context & context;
const bool is_local;
std::unique_ptr<ConnectionPool> pool;
const std::string load_all_query;
};
}