added EPHEMERAL default for column (preliminary)

src/Interpreters/processColumnTransformers.cpp

@@ -19,7 +19,7 @@ ASTPtr processColumnTransformers(
         ASTPtr query_columns)
 {
     const auto & columns = metadata_snapshot->getColumns();
-    auto names_and_types = columns.getOrdinary();
+    auto names_and_types = columns.getInsertable();
     removeDuplicateColumns(names_and_types);
 
     TablesWithColumns tables_with_columns;

src/Parsers/ParserCreateQuery.h

@@ -124,6 +124,7 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
     ParserKeyword s_null{"NULL"};
     ParserKeyword s_not{"NOT"};
     ParserKeyword s_materialized{"MATERIALIZED"};
+    ParserKeyword s_ephemeral{"EPHEMERAL"};
     ParserKeyword s_alias{"ALIAS"};
     ParserKeyword s_comment{"COMMENT"};
     ParserKeyword s_codec{"CODEC"};
@@ -171,6 +172,7 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
 
     if (!s_default.checkWithoutMoving(pos, expected)
         && !s_materialized.checkWithoutMoving(pos, expected)
+        && !s_ephemeral.checkWithoutMoving(pos, expected)
         && !s_alias.checkWithoutMoving(pos, expected)
         && (require_type
             || (!s_comment.checkWithoutMoving(pos, expected)
@@ -190,6 +192,9 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
         /// should be followed by an expression
         if (!expr_parser.parse(pos, default_expression, expected))
             return false;
+    } else if (s_ephemeral.ignore(pos, expected)) {
+        default_specifier = Poco::toUpper(std::string{pos_before_specifier->begin, pos_before_specifier->end});
+        expr_parser.parse(pos, default_expression, expected);
     }
 
     if (require_type && !type && !default_expression)

src/Parsers/obfuscateQueries.cpp

@@ -26,20 +26,20 @@ namespace
 
 const std::unordered_set<std::string_view> keywords
 {
-    "CREATE",       "DATABASE", "IF",     "NOT",       "EXISTS",   "TEMPORARY",   "TABLE",    "ON",          "CLUSTER", "DEFAULT",
+    "CREATE",       "DATABASE",   "IF",       "NOT",      "EXISTS",    "TEMPORARY", "TABLE",       "ON",         "CLUSTER",     "DEFAULT",
-    "MATERIALIZED", "ALIAS",    "ENGINE", "AS",        "VIEW",     "POPULATE",    "SETTINGS", "ATTACH",      "DETACH",  "DROP",
+    "MATERIALIZED", "EPHEMERAL",  "ALIAS",    "ENGINE",   "AS",        "VIEW",      "POPULATE",    "SETTINGS",   "ATTACH",      "DETACH",
-    "RENAME",       "TO",       "ALTER",  "ADD",       "MODIFY",   "CLEAR",       "COLUMN",   "AFTER",       "COPY",    "PROJECT",
+    "DROP",         "RENAME",     "TO",       "ALTER",    "ADD",       "MODIFY",    "CLEAR",       "COLUMN",     "AFTER",       "COPY",
-    "PRIMARY",      "KEY",      "CHECK",  "PARTITION", "PART",     "FREEZE",      "FETCH",    "FROM",        "SHOW",    "INTO",
+    "PROJECT",      "PRIMARY",    "KEY",      "CHECK",    "PARTITION", "PART",      "FREEZE",      "FETCH",      "FROM",        "SHOW",
-    "OUTFILE",      "FORMAT",   "TABLES", "DATABASES", "LIKE",     "PROCESSLIST", "CASE",     "WHEN",        "THEN",    "ELSE",
+    "INTO",         "OUTFILE",    "FORMAT",   "TABLES",   "DATABASES", "LIKE",      "PROCESSLIST", "CASE",       "WHEN",        "THEN",
-    "END",          "DESCRIBE", "DESC",   "USE",       "SET",      "OPTIMIZE",    "FINAL",    "DEDUPLICATE", "INSERT",  "VALUES",
+    "ELSE",         "END",        "DESCRIBE", "DESC",     "USE",       "SET",       "OPTIMIZE",    "FINAL",      "DEDUPLICATE", "INSERT",
-    "SELECT",       "DISTINCT", "SAMPLE", "ARRAY",     "JOIN",     "GLOBAL",      "LOCAL",    "ANY",         "ALL",     "INNER",
+    "VALUES",       "SELECT",     "DISTINCT", "SAMPLE",   "ARRAY",     "JOIN",      "GLOBAL",      "LOCAL",      "ANY",         "ALL",
-    "LEFT",         "RIGHT",    "FULL",   "OUTER",     "CROSS",    "USING",       "PREWHERE", "WHERE",       "GROUP",   "BY",
+    "INNER",        "LEFT",       "RIGHT",    "FULL",     "OUTER",     "CROSS",     "USING",       "PREWHERE",   "WHERE",       "GROUP",
-    "WITH",         "TOTALS",   "HAVING", "ORDER",     "COLLATE",  "LIMIT",       "UNION",    "AND",         "OR",      "ASC",
+    "BY",           "WITH",       "TOTALS",   "HAVING",   "ORDER",     "COLLATE",   "LIMIT",       "UNION",      "AND",         "OR",
-    "IN",           "KILL",     "QUERY",  "SYNC",      "ASYNC",    "TEST",        "BETWEEN",  "TRUNCATE",    "USER",    "ROLE",
+    "ASC",          "IN",         "KILL",     "QUERY",    "SYNC",      "ASYNC",     "TEST",        "BETWEEN",    "TRUNCATE",    "USER",
-    "PROFILE",      "QUOTA",    "POLICY", "ROW",       "GRANT",    "REVOKE",      "OPTION",   "ADMIN",       "EXCEPT",  "REPLACE",
+    "ROLE",         "PROFILE",    "QUOTA",    "POLICY",   "ROW",       "GRANT",     "REVOKE",      "OPTION",     "ADMIN",       "EXCEPT",
-    "IDENTIFIED",   "HOST",     "NAME",   "READONLY",  "WRITABLE", "PERMISSIVE",  "FOR",      "RESTRICTIVE", "RANDOMIZED",
+    "REPLACE",      "IDENTIFIED", "HOST",     "NAME",     "READONLY",  "WRITABLE",  "PERMISSIVE",  "FOR",        "RESTRICTIVE", "RANDOMIZED",
-    "INTERVAL",     "LIMITS",   "ONLY",   "TRACKING",  "IP",       "REGEXP",      "ILIKE",    "DICTIONARY",  "OFFSET",
+    "INTERVAL",     "LIMITS",     "ONLY",     "TRACKING", "IP",        "REGEXP",    "ILIKE",       "DICTIONARY", "OFFSET",      "TRIM",
-    "TRIM", "LTRIM", "RTRIM", "BOTH", "LEADING", "TRAILING"
+    "LTRIM",        "RTRIM",      "BOTH",     "LEADING",  "TRAILING"
 };
 
 const std::unordered_set<std::string_view> keep_words

src/Storages/ColumnDefault.cpp

@@ -9,6 +9,7 @@ struct AliasNames
     static constexpr const char * DEFAULT = "DEFAULT";
     static constexpr const char * MATERIALIZED = "MATERIALIZED";
     static constexpr const char * ALIAS = "ALIAS";
+    static constexpr const char * EPHEMERAL = "EPHEMERAL";
 };
 
 }
@@ -27,7 +28,8 @@ ColumnDefaultKind columnDefaultKindFromString(const std::string & str)
     static const std::unordered_map<std::string, ColumnDefaultKind> map{
         { AliasNames::DEFAULT, ColumnDefaultKind::Default },
         { AliasNames::MATERIALIZED, ColumnDefaultKind::Materialized },
-        { AliasNames::ALIAS, ColumnDefaultKind::Alias }
+        { AliasNames::ALIAS, ColumnDefaultKind::Alias },
+        { AliasNames::EPHEMERAL, ColumnDefaultKind::Ephemeral }
     };
 
     const auto it = map.find(str);
@@ -43,7 +45,8 @@ std::string toString(const ColumnDefaultKind kind)
     static const std::unordered_map<ColumnDefaultKind, std::string> map{
         { ColumnDefaultKind::Default, AliasNames::DEFAULT },
         { ColumnDefaultKind::Materialized, AliasNames::MATERIALIZED },
-        { ColumnDefaultKind::Alias, AliasNames::ALIAS }
+        { ColumnDefaultKind::Alias, AliasNames::ALIAS },
+        { ColumnDefaultKind::Ephemeral, AliasNames::EPHEMERAL }
     };
 
     const auto it = map.find(kind);

src/Storages/ColumnDefault.h

@@ -13,7 +13,8 @@ enum class ColumnDefaultKind
 {
     Default,
     Materialized,
-    Alias
+    Alias,
+    Ephemeral
 };
 
 

src/Storages/ColumnsDescription.cpp

@@ -340,6 +340,15 @@ NamesAndTypesList ColumnsDescription::getOrdinary() const
     return ret;
 }
 
+NamesAndTypesList ColumnsDescription::getInsertable() const
+{
+    NamesAndTypesList ret;
+    for (const auto & col : columns)
+        if (col.default_desc.kind == ColumnDefaultKind::Default || col.default_desc.kind == ColumnDefaultKind::Ephemeral)
+            ret.emplace_back(col.name, col.type);
+    return ret;
+}
+
 NamesAndTypesList ColumnsDescription::getMaterialized() const
 {
     NamesAndTypesList ret;
@@ -358,6 +367,15 @@ NamesAndTypesList ColumnsDescription::getAliases() const
     return ret;
 }
 
+NamesAndTypesList ColumnsDescription::getEphemeral() const
+{
+    NamesAndTypesList ret;
+        for (const auto & col : columns)
+            if (col.default_desc.kind == ColumnDefaultKind::Ephemeral)
+                ret.emplace_back(col.name, col.type);
+    return ret;
+}
+
 NamesAndTypesList ColumnsDescription::getAll() const
 {
     NamesAndTypesList ret;
@@ -402,6 +420,8 @@ static ColumnsDescription::GetFlags defaultKindToGetFlag(ColumnDefaultKind kind)
             return ColumnsDescription::Materialized;
         case ColumnDefaultKind::Alias:
             return ColumnsDescription::Aliases;
+        case ColumnDefaultKind::Ephemeral:
+            return ColumnsDescription::Ephemeral;
     }
     __builtin_unreachable();
 }

src/Storages/ColumnsDescription.h

@@ -84,18 +84,21 @@ public:
         Ordinary = 1,
         Materialized = 2,
         Aliases = 4,
+	Ephemeral = 8,
 
         AllPhysical = Ordinary | Materialized,
-        All = AllPhysical | Aliases,
+        All = AllPhysical | Aliases | Ephemeral,
     };
 
     NamesAndTypesList getByNames(GetFlags flags, const Names & names, bool with_subcolumns) const;
 
     NamesAndTypesList getOrdinary() const;
     NamesAndTypesList getMaterialized() const;
+    NamesAndTypesList getInsertable() const;
     NamesAndTypesList getAliases() const;
+    NamesAndTypesList getEphemeral() const;
     NamesAndTypesList getAllPhysical() const; /// ordinary + materialized.
-    NamesAndTypesList getAll() const; /// ordinary + materialized + aliases
+    NamesAndTypesList getAll() const; /// ordinary + materialized + aliases + ephemeral
     NamesAndTypesList getAllWithSubcolumns() const;
     NamesAndTypesList getAllPhysicalWithSubcolumns() const;
 

src/Storages/StorageInMemoryMetadata.cpp

@@ -304,7 +304,7 @@ Block StorageInMemoryMetadata::getSampleBlockNonMaterialized() const
 {
     Block res;
 
-    for (const auto & column : getColumns().getOrdinary())
+    for (const auto & column : getColumns().getInsertable())
         res.insert({column.type->createColumn(), column.type, column.name});
 
     return res;