ClickHouse/src/Storages/StorageInMemoryMetadata.h
2020-05-28 18:33:44 +03:00

76 lines
3.0 KiB
C++

#pragma once
#include <Storages/ColumnsDescription.h>
#include <Storages/IndicesDescription.h>
#include <Storages/ConstraintsDescription.h>
#include <Parsers/IAST_fwd.h>
namespace DB
{
/// Structure represent table metadata stored in memory.
/// Only one storage engine support all fields -- MergeTree.
/// Complete table AST can be recreated from this struct.
struct StorageInMemoryMetadata
{
/// Columns of table with their names, types,
/// defaults, comments, etc. All table engines have columns.
ColumnsDescription columns;
/// Table indices. Currently supported for MergeTree only.
IndicesDescription indices;
/// Table constraints. Currently supported for MergeTree only.
ConstraintsDescription constraints;
/// PARTITION BY expression. Currently supported for MergeTree only.
ASTPtr partition_by_ast = nullptr;
/// ORDER BY expression. Required field for all MergeTree tables
/// even in old syntax MergeTree(partition_key, order_by, ...)
ASTPtr order_by_ast = nullptr;
/// PRIMARY KEY expression. If absent, than equal to order_by_ast.
ASTPtr primary_key_ast = nullptr;
/// TTL expression for whole table. Supported for MergeTree only.
ASTPtr ttl_for_table_ast = nullptr;
/// SAMPLE BY expression. Supported for MergeTree only.
ASTPtr sample_by_ast = nullptr;
/// SETTINGS expression. Supported for MergeTree, Buffer and Kafka.
ASTPtr settings_ast = nullptr;
/// SELECT QUERY. Supported for MaterializedView only.
ASTPtr select = nullptr;
StorageInMemoryMetadata(const StorageInMemoryMetadata & other);
StorageInMemoryMetadata() = default;
StorageInMemoryMetadata(const ColumnsDescription & columns_, const IndicesDescription & indices_, const ConstraintsDescription & constraints_);
StorageInMemoryMetadata & operator=(const StorageInMemoryMetadata & other);
};
/// Common structure for primary, partition and other storage keys
struct StorageMetadataKeyField
{
/// User defined AST in CREATE/ALTER query. This field may be empty, but key
/// can exists because some of them maybe set implicitly (for example,
/// primary key in merge tree can be part of sorting key)
ASTPtr definition_ast;
/// ASTExpressionList with key fields, example: (x, toStartOfMonth(date))).
ASTPtr expression_list_ast;
/// Expression from expression_list_ast created by ExpressionAnalyzer. Useful,
/// when you need to get required columns for key, example: a, date, b.
ExpressionActionsPtr expression;
/// Sample block with key columns (names, types, empty column)
Block sample_block;
/// Column names in key definition, example: x, toStartOfMonth(date), a * b.
Names column_names;
/// Types from sample block ordered in columns order.
DataTypes data_types;
/// Parse key structure from key definition. Requires all columns, available
/// in storage.
static StorageMetadataKeyField getKeyFromAST(const ASTPtr & definition_ast, const ColumnsDescription & columns, const Context & context);
};
}