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110 lines
2.7 KiB
C++
110 lines
2.7 KiB
C++
#include <DB/Columns/ColumnString.h>
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#include <DB/DataTypes/DataTypeString.h>
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#include <DB/DataStreams/OneBlockInputStream.h>
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#include <DB/Storages/System/StorageSystemTables.h>
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#include <DB/Common/VirtualColumnUtils.h>
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#include <DB/Databases/IDatabase.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int LOGICAL_ERROR;
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}
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StorageSystemTables::StorageSystemTables(const std::string & name_)
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: name(name_),
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columns
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{
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{"database", new DataTypeString},
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{"name", new DataTypeString},
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{"engine", new DataTypeString},
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}
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{
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}
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StoragePtr StorageSystemTables::create(const std::string & name_)
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{
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return (new StorageSystemTables(name_))->thisPtr();
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}
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static ColumnWithTypeAndName getFilteredDatabases(ASTPtr query, const Context & context)
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{
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ColumnWithTypeAndName column;
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column.name = "database";
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column.type = new DataTypeString;
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column.column = std::make_shared<ColumnString>();
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Block block;
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block.insert(column);
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for (const auto & db : context.getDatabases())
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column.column->insert(db.first);
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VirtualColumnUtils::filterBlockWithQuery(query, block, context);
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return block.getByPosition(0);
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}
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BlockInputStreams StorageSystemTables::read(
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const Names & column_names,
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ASTPtr query,
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const Context & context,
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const Settings & settings,
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QueryProcessingStage::Enum & processed_stage,
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const size_t max_block_size,
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const unsigned threads)
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{
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check(column_names);
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processed_stage = QueryProcessingStage::FetchColumns;
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Block block;
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ColumnWithTypeAndName col_db;
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col_db.name = "database";
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col_db.type = new DataTypeString;
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col_db.column = std::make_shared<ColumnString>();
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block.insert(col_db);
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ColumnWithTypeAndName col_name;
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col_name.name = "name";
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col_name.type = new DataTypeString;
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col_name.column = std::make_shared<ColumnString>();
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block.insert(col_name);
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ColumnWithTypeAndName col_engine;
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col_engine.name = "engine";
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col_engine.type = new DataTypeString;
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col_engine.column = std::make_shared<ColumnString>();
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block.insert(col_engine);
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ColumnWithTypeAndName filtered_databases_column = getFilteredDatabases(query, context);
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for (size_t row_number = 0; row_number < filtered_databases_column.column->size(); ++row_number)
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{
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std::string database_name = filtered_databases_column.column->getDataAt(row_number).toString();
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auto database = context.tryGetDatabase(database_name);
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if (!database)
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{
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/// Базу данных только что удалили.
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continue;
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}
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for (auto iterator = database->getIterator(); iterator->isValid(); iterator->next())
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{
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col_db.column->insert(database_name);
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col_name.column->insert(iterator->name());
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col_engine.column->insert(iterator->table()->getName());
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}
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}
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return BlockInputStreams(1, new OneBlockInputStream(block));
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}
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}
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