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#pragma once
#include <QueryPipeline/BlockIO.h>
#include <Interpreters/Context_fwd.h>
#include <Parsers/IAST_fwd.h>
#include <Storages//IStorage_fwd.h>
namespace DB
{
struct QueryLogElement;
/** Interpreters interface for different queries.
*/
class IInterpreter
{
public:
/** For queries that return a result (SELECT and similar), sets in BlockIO a stream from which you can read this result.
* For queries that receive data (INSERT), sets a thread in BlockIO where you can write data.
* For queries that do not require data and return nothing, BlockIO will be empty.
*/
virtual BlockIO execute() = 0;
virtual bool ignoreQuota() const { return false; }
virtual bool ignoreLimits() const { return false; }
// Fill query log element with query kind, query databases, query tables and query columns.
void extendQueryLogElem(
QueryLogElement & elem,
const ASTPtr & ast,
ContextPtr context,
const String & query_database,
const String & query_table) const;
virtual void extendQueryLogElemImpl(QueryLogElement &, const ASTPtr &, ContextPtr) const {}
/// Returns true if transactions maybe supported for this type of query.
/// If Interpreter returns true, than it is responsible to check that specific query with specific Storage is supported.
virtual bool supportsTransactions() const { return false; }
/// Helper function for some Interpreters.
static void checkStorageSupportsTransactionsIfNeeded(const StoragePtr & storage, ContextPtr context, bool is_readonly_query = false);
virtual ~IInterpreter() = default;
};
}
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