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