ClickHouse/dbms/include/DB/Dictionaries/MySQLDictionarySource.h
2016-04-10 07:00:00 +03:00

177 lines
5.0 KiB
C++

#pragma once
#include <DB/Dictionaries/IDictionarySource.h>
#include <DB/Dictionaries/MySQLBlockInputStream.h>
#include <DB/Dictionaries/ExternalQueryBuilder.h>
#include <ext/range.hpp>
#include <mysqlxx/Pool.h>
#include <Poco/Util/AbstractConfiguration.h>
namespace DB
{
/// Allows loading dictionaries from a MySQL database
class MySQLDictionarySource final : public IDictionarySource
{
static const auto max_block_size = 8192;
public:
MySQLDictionarySource(const DictionaryStructure & dict_struct_,
const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
const Block & sample_block)
: dict_struct{dict_struct_},
db{config.getString(config_prefix + ".db", "")},
table{config.getString(config_prefix + ".table")},
where{config.getString(config_prefix + ".where", "")},
dont_check_update_time{config.getBool(config_prefix + ".dont_check_update_time", false)},
sample_block{sample_block},
pool{config, config_prefix},
query_builder{dict_struct, db, table, where},
load_all_query{query_builder.composeLoadAllQuery()}
{}
/// copy-constructor is provided in order to support cloneability
MySQLDictionarySource(const MySQLDictionarySource & other)
: dict_struct{other.dict_struct},
db{other.db},
table{other.table},
where{other.where},
dont_check_update_time{other.dont_check_update_time},
sample_block{other.sample_block},
pool{other.pool},
query_builder{dict_struct, db, table, where},
load_all_query{other.load_all_query}, last_modification{other.last_modification}
{}
BlockInputStreamPtr loadAll() override
{
last_modification = getLastModification();
LOG_TRACE(log, load_all_query);
return new MySQLBlockInputStream{pool.Get(), load_all_query, sample_block, max_block_size};
}
BlockInputStreamPtr loadIds(const std::vector<std::uint64_t> & ids) override
{
/// Здесь не логгируем и не обновляем время модификации, так как запрос может быть большим, и часто задаваться.
const auto query = query_builder.composeLoadIdsQuery(ids);
return new MySQLBlockInputStream{pool.Get(), query, sample_block, max_block_size};
}
BlockInputStreamPtr loadKeys(
const ConstColumnPlainPtrs & key_columns, const std::vector<std::size_t> & requested_rows) override
{
/// Здесь не логгируем и не обновляем время модификации, так как запрос может быть большим, и часто задаваться.
const auto query = query_builder.composeLoadKeysQuery(key_columns, requested_rows, ExternalQueryBuilder::AND_OR_CHAIN);
return new MySQLBlockInputStream{pool.Get(), query, sample_block, max_block_size};
}
bool isModified() const override
{
if (dont_check_update_time)
return true;
return getLastModification() > last_modification;
}
bool supportsSelectiveLoad() const override { return true; }
DictionarySourcePtr clone() const override { return std::make_unique<MySQLDictionarySource>(*this); }
std::string toString() const override
{
return "MySQL: " + db + '.' + table + (where.empty() ? "" : ", where: " + where);
}
private:
Logger * log = &Logger::get("MySQLDictionarySource");
static std::string quoteForLike(const std::string s)
{
std::string tmp;
tmp.reserve(s.size());
for (auto c : s)
{
if (c == '%' || c == '_' || c == '\\')
tmp.push_back('\\');
tmp.push_back(c);
}
std::string res;
{
WriteBufferFromString out(res);
writeQuoted(tmp, out);
}
return res;
}
LocalDateTime getLastModification() const
{
LocalDateTime update_time{std::time(nullptr)};
if (dont_check_update_time)
return update_time;
try
{
auto connection = pool.Get();
auto query = connection->query("SHOW TABLE STATUS LIKE " + quoteForLike(table));
LOG_TRACE(log, query.str());
auto result = query.use();
size_t fetched_rows = 0;
if (auto row = result.fetch())
{
++fetched_rows;
const auto UPDATE_TIME_IDX = 12;
const auto & update_time_value = row[UPDATE_TIME_IDX];
if (!update_time_value.isNull())
{
update_time = update_time_value.getDateTime();
LOG_TRACE(log, "Got update time: " << update_time);
}
/// fetch remaining rows to avoid "commands out of sync" error
while (result.fetch())
++fetched_rows;
}
if (0 == fetched_rows)
LOG_ERROR(log, "Cannot find table in SHOW TABLE STATUS result.");
if (fetched_rows > 1)
LOG_ERROR(log, "Found more than one table in SHOW TABLE STATUS result.");
}
catch (...)
{
tryLogCurrentException("MySQLDictionarySource");
}
/// we suppose failure to get modification time is not an error, therefore return current time
return update_time;
}
const DictionaryStructure dict_struct;
const std::string db;
const std::string table;
const std::string where;
const bool dont_check_update_time;
Block sample_block;
mutable mysqlxx::PoolWithFailover pool;
ExternalQueryBuilder query_builder;
const std::string load_all_query;
LocalDateTime last_modification;
};
}