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#pragma once
#include <string>
#include <Columns/IColumn.h>
#include <Dictionaries/DictionaryStructure.h>
#include <Formats/FormatSettings.h>
#include <Parsers/IdentifierQuotingStyle.h>
namespace DB
{
struct DictionaryStructure;
class WriteBuffer;
/** Builds a query to load data from external database.
*/
struct ExternalQueryBuilder
{
const DictionaryStructure dict_struct;
const std::string db;
const std::string schema;
const std::string table;
const std::string query;
const std::string where;
IdentifierQuotingStyle quoting_style;
ExternalQueryBuilder(
const DictionaryStructure & dict_struct_,
const std::string & db_,
const std::string & schema_,
const std::string & table_,
const std::string & query_,
const std::string & where_,
IdentifierQuotingStyle quoting_style_);
ExternalQueryBuilder(const ExternalQueryBuilder &) = default;
virtual ~ExternalQueryBuilder() = default;
/** Generate a query to load all data. */
std::string composeLoadAllQuery() const;
/** Generate a query to load data after certain time point */
std::string composeUpdateQuery(const std::string & update_field, const std::string & time_point) const;
/** Generate a query to load data by set of UInt64 keys. */
std::string composeLoadIdsQuery(const std::vector<UInt64> & ids) const;
/** Generate a query to load data by set of composite keys.
* There are three methods of specification of composite keys in WHERE:
* 1. (x = c11 AND y = c12) OR (x = c21 AND y = c22) ...
* 2. (x, y) IN ((c11, c12), (c21, c22), ...)
* 3. (x = c1 AND (y, z) IN ((c2, c3), ...))
*/
enum LoadKeysMethod
{
AND_OR_CHAIN,
IN_WITH_TUPLES,
CASSANDRA_SEPARATE_PARTITION_KEY,
};
std::string composeLoadKeysQuery(const Columns & key_columns, const std::vector<size_t> & requested_rows, LoadKeysMethod method, size_t partition_key_prefix = 0) const;
protected:
const FormatSettings format_settings = {};
virtual void composeLoadAllQuery(WriteBuffer & out) const;
/// In the following methods `beg` and `end` specifies which columns to write in expression
/// Expression in form (x = c1 AND y = c2 ...)
void composeKeyCondition(const Columns & key_columns, size_t row, WriteBuffer & out, size_t beg, size_t end) const;
/// Expression in form (x, y, ...) IN ((c1, c2, ...), ...)
void composeInWithTuples(const Columns & key_columns, const std::vector<size_t> & requested_rows, WriteBuffer & out, size_t beg, size_t end) const;
/// Expression in form (x, y, ...)
void composeKeyTupleDefinition(WriteBuffer & out, size_t beg, size_t end) const;
/// Expression in form (c1, c2, ...)
void composeKeyTuple(const Columns & key_columns, size_t row, WriteBuffer & out, size_t beg, size_t end) const;
/// Compose update condition
static void composeUpdateCondition(const std::string & update_field, const std::string & time_point, WriteBuffer & out);
/// Compose ids condition
void composeIdsCondition(const std::vector<UInt64> & ids, WriteBuffer & out) const;
/// Compose keys condition
void composeKeysCondition(const Columns & key_columns, const std::vector<size_t> & requested_rows, LoadKeysMethod method, size_t partition_key_prefix, WriteBuffer & out) const;
/// Write string with specified quoting style.
void writeQuoted(const std::string & s, WriteBuffer & out) const;
};
using ExternalQueryBuilderPtr = std::shared_ptr<ExternalQueryBuilder>;
}
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