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Merge pull request #35706 from yakov-olkhovskiy/ephemeral-35641

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Allow EPHEMERAL without explicit default expression
This commit is contained in:
Yakov Olkhovskiy 2022-04-01 10:49:29 -04:00 committed by GitHub
commit 38993f215f
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7 changed files with 75 additions and 10 deletions
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4
docs/en/sql-reference/statements/create/table.md
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@ -114,9 +114,9 @@ In addition, this column is not substituted when using an asterisk in a SELECT q
### EPHEMERAL {#ephemeral}
`EPHEMERAL expr`
`EPHEMERAL [expr]`
Ephemeral column. Such a column isn't stored in the table and cannot be SELECTed, but can be referenced in the defaults of CREATE statement.
Ephemeral column. Such a column isn't stored in the table and cannot be SELECTed, but can be referenced in the defaults of CREATE statement. If `expr` is omitted type for column is required.
INSERT without list of columns will skip such column, so SELECT/INSERT invariant is preserved - the dump obtained using `SELECT *` can be inserted back into the table using INSERT without specifying the list of columns.
### ALIAS {#alias}

4
docs/ru/sql-reference/statements/create/table.md
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@ -110,9 +110,9 @@ SELECT x, toTypeName(x) FROM t1;
### EPHEMERAL {#ephemeral}
`EPHEMERAL expr`
`EPHEMERAL [expr]`
Эфемерное выражение. Такой столбец не хранится в таблице и не может быть получен в запросе SELECT, но на него можно ссылаться в выражениях по умолчанию запроса CREATE.
Эфемерное выражение. Такой столбец не хранится в таблице и не может быть получен в запросе SELECT, но на него можно ссылаться в выражениях по умолчанию запроса CREATE. Если значение по умолчанию `expr` не указано, то тип колонки должен быть специфицирован.
INSERT без списка столбцов игнорирует этот столбец, таким образом сохраняется инвариант - т.е. дамп, полученный путём `SELECT *`, можно вставить обратно в таблицу INSERT-ом без указания списка столбцов.
### ALIAS {#alias}

10
src/Interpreters/InterpreterCreateQuery.cpp
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@ -508,7 +508,9 @@ ColumnsDescription InterpreterCreateQuery::getColumnsDescription(
default_expr_list->children.emplace_back(
setAlias(
col_decl.default_expression->clone(),
col_decl.default_specifier == "EPHEMERAL" ? /// can be ASTLiteral::value NULL
std::make_shared<ASTLiteral>(data_type_ptr->getDefault()) :
col_decl.default_expression->clone(),
tmp_column_name));
}
else
@ -536,7 +538,11 @@ ColumnsDescription InterpreterCreateQuery::getColumnsDescription(
if (col_decl.default_expression)
{
ASTPtr default_expr = col_decl.default_expression->clone();
ASTPtr default_expr =
col_decl.default_specifier == "EPHEMERAL" && col_decl.default_expression->as<ASTLiteral>()->value.isNull() ?
std::make_shared<ASTLiteral>(DataTypeFactory::instance().get(col_decl.type)->getDefault()) :
col_decl.default_expression->clone();
if (col_decl.type)
column.type = name_type_it->type;
else

9
src/Parsers/ASTColumnDeclaration.cpp
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@ -1,6 +1,7 @@
#include <Parsers/ASTColumnDeclaration.h>
#include <Common/quoteString.h>
#include <IO/Operators.h>
#include <Parsers/ASTLiteral.h>
namespace DB
@ -71,8 +72,12 @@ void ASTColumnDeclaration::formatImpl(const FormatSettings & settings, FormatSta
if (default_expression)
{
settings.ostr << ' ' << (settings.hilite ? hilite_keyword : "") << default_specifier << (settings.hilite ? hilite_none : "") << ' ';
default_expression->formatImpl(settings, state, frame);
settings.ostr << ' ' << (settings.hilite ? hilite_keyword : "") << default_specifier << (settings.hilite ? hilite_none : "");
if (default_specifier != "EPHEMERAL" || !default_expression->as<ASTLiteral>()->value.isNull())
{
settings.ostr << ' ';
default_expression->formatImpl(settings, state, frame);
}
}
if (comment)

10
src/Parsers/ParserCreateQuery.h
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@ -9,6 +9,7 @@
#include <Parsers/CommonParsers.h>
#include <Parsers/ParserDataType.h>
#include <Poco/String.h>
#include <Parsers/ASTLiteral.h>
namespace DB
@ -185,8 +186,7 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
}
Pos pos_before_specifier = pos;
if (s_default.ignore(pos, expected) || s_materialized.ignore(pos, expected) ||
s_ephemeral.ignore(pos, expected) || s_alias.ignore(pos, expected))
if (s_default.ignore(pos, expected) || s_materialized.ignore(pos, expected) || s_alias.ignore(pos, expected))
{
default_specifier = Poco::toUpper(std::string{pos_before_specifier->begin, pos_before_specifier->end});
@ -194,6 +194,12 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
if (!expr_parser.parse(pos, default_expression, expected))
return false;
}
else if (s_ephemeral.ignore(pos, expected))
{
default_specifier = "EPHEMERAL";
if (!expr_parser.parse(pos, default_expression, expected) && type)
default_expression = std::make_shared<ASTLiteral>(Field());
}
if (require_type && !type && !default_expression)
return false; /// reject column name without type

8
tests/queries/0_stateless/02205_ephemeral_1.reference
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@ -6,3 +6,11 @@ z UInt32 DEFAULT 5
17 5
7 5
21 5
x UInt32 DEFAULT y
y UInt32 EPHEMERAL 0
z UInt32 DEFAULT 5
1 2
0 2
0 5
7 5
21 5

40
tests/queries/0_stateless/02205_ephemeral_1.sql
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@ -38,3 +38,43 @@ SELECT * FROM t_ephemeral_02205_1;
DROP TABLE IF EXISTS t_ephemeral_02205_1;
# Test without default
CREATE TABLE t_ephemeral_02205_1 (x UInt32 DEFAULT y, y UInt32 EPHEMERAL, z UInt32 DEFAULT 5) ENGINE = Memory;
DESCRIBE t_ephemeral_02205_1;
# Test INSERT without columns list - should participate only ordinary columns (x, z)
INSERT INTO t_ephemeral_02205_1 VALUES (1, 2);
# SELECT * should only return ordinary columns (x, z) - ephemeral is not stored in the table
SELECT * FROM t_ephemeral_02205_1;
TRUNCATE TABLE t_ephemeral_02205_1;
INSERT INTO t_ephemeral_02205_1 VALUES (DEFAULT, 2);
SELECT * FROM t_ephemeral_02205_1;
TRUNCATE TABLE t_ephemeral_02205_1;
# Test INSERT using ephemerals default
INSERT INTO t_ephemeral_02205_1 (x, y) VALUES (DEFAULT, DEFAULT);
SELECT * FROM t_ephemeral_02205_1;
TRUNCATE TABLE t_ephemeral_02205_1;
# Test INSERT using explicit ephemerals value
INSERT INTO t_ephemeral_02205_1 (x, y) VALUES (DEFAULT, 7);
SELECT * FROM t_ephemeral_02205_1;
# Test ALTER TABLE DELETE
ALTER TABLE t_ephemeral_02205_1 DELETE WHERE x = 7;
SELECT * FROM t_ephemeral_02205_1;
TRUNCATE TABLE t_ephemeral_02205_1;
# Test INSERT into column, defaulted to ephemeral, but explicitly provided with value
INSERT INTO t_ephemeral_02205_1 (x, y) VALUES (21, 7);
SELECT * FROM t_ephemeral_02205_1;
DROP TABLE IF EXISTS t_ephemeral_02205_1;