ClickHouse/src/Parsers/QueryWithOutputSettingsPushDownVisitor.h

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#pragma once
#include <Parsers/IAST.h>
#include <Interpreters/InDepthNodeVisitor.h>
namespace DB
{
class ASTSelectQuery;
struct SettingChange;
2020-07-22 12:02:47 +00:00
class SettingsChanges;
/// Pushdown SETTINGS clause that goes after FORMAT to the SELECT query:
/// (since settings after FORMAT parsed separatelly not in the ParserSelectQuery but in ParserQueryWithOutput)
///
/// SELECT 1 FORMAT Null SETTINGS max_block_size = 1 ->
/// SELECT 1 SETTINGS max_block_size = 1 FORMAT Null SETTINGS max_block_size = 1
///
/// Otherwise settings after FORMAT will not be applied.
class QueryWithOutputSettingsPushDownMatcher
{
public:
using Visitor = InDepthNodeVisitor<QueryWithOutputSettingsPushDownMatcher, true>;
struct Data
{
const ASTPtr & settings_ast;
};
static bool needChildVisit(ASTPtr & node, const ASTPtr & child);
static void visit(ASTPtr & ast, Data & data);
private:
static void visit(ASTSelectQuery &, ASTPtr &, Data &);
};
using QueryWithOutputSettingsPushDownVisitor = QueryWithOutputSettingsPushDownMatcher::Visitor;
}