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48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
#pragma once
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#include <TableFunctions/ITableFunction.h>
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#include <Interpreters/Cluster.h>
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#include <Interpreters/StorageID.h>
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namespace DB
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{
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/* remote ('address', db, table) - creates a temporary StorageDistributed.
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* To get the table structure, a DESC TABLE request is made to the remote server.
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* For example:
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* SELECT count() FROM remote('example01-01-1', merge, hits) - go to `example01-01-1`, in the merge database, the hits table.
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* An expression that generates a set of shards and replicas can also be specified as the host name - see below.
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* Also, there is a cluster version of the function: cluster('existing_cluster_name', 'db', 'table').
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*/
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class TableFunctionRemote : public ITableFunction
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{
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public:
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explicit TableFunctionRemote(const std::string & name_, bool secure_ = false);
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std::string getName() const override { return name; }
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ColumnsDescription getActualTableStructure(ContextPtr context) const override;
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bool needStructureConversion() const override { return false; }
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private:
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StoragePtr executeImpl(const ASTPtr & ast_function, ContextPtr context, const std::string & table_name, ColumnsDescription cached_columns) const override;
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const char * getStorageTypeName() const override { return "Distributed"; }
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void parseArguments(const ASTPtr & ast_function, ContextPtr context) override;
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std::string name;
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bool is_cluster_function;
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std::string help_message;
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bool secure;
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ClusterPtr cluster;
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StorageID remote_table_id = StorageID::createEmpty();
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ASTPtr remote_table_function_ptr;
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ASTPtr sharding_key = nullptr;
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};
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}
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