flink流计算随笔（8）

SQL标准的Apache Calcite

statement:
      setStatement
  |   resetStatement
  |   explain
  |   describe
  |   insert
  |   update
  |   merge
  |   delete
  |   query

setStatement:
      [ ALTER ( SYSTEM | SESSION ) ] SET identifier '=' expression

resetStatement:
      [ ALTER ( SYSTEM | SESSION ) ] RESET identifier
  |   [ ALTER ( SYSTEM | SESSION ) ] RESET ALL

explain:
      EXPLAIN PLAN
      [ WITH TYPE | WITH IMPLEMENTATION | WITHOUT IMPLEMENTATION ]
      [ EXCLUDING ATTRIBUTES | INCLUDING [ ALL ] ATTRIBUTES ]
      [ AS JSON | AS XML ]
      FOR ( query | insert | update | merge | delete )

describe:
      DESCRIBE DATABASE databaseName
   |  DESCRIBE CATALOG [ databaseName . ] catalogName
   |  DESCRIBE SCHEMA [ [ databaseName . ] catalogName ] . schemaName
   |  DESCRIBE [ TABLE ] [ [ [ databaseName . ] catalogName . ] schemaName . ] tableName [ columnName ]
   |  DESCRIBE [ STATEMENT ] ( query | insert | update | merge | delete )

insert:
      ( INSERT | UPSERT ) INTO tablePrimary
      [ '(' column [, column ]* ')' ]
      query

update:
      UPDATE tablePrimary
      SET assign [, assign ]*
      [ WHERE booleanExpression ]

assign:
      identifier '=' expression

merge:
      MERGE INTO tablePrimary [ [ AS ] alias ]
      USING tablePrimary
      ON booleanExpression
      [ WHEN MATCHED THEN UPDATE SET assign [, assign ]* ]
      [ WHEN NOT MATCHED THEN INSERT VALUES '(' value [ , value ]* ')' ]

delete:
      DELETE FROM tablePrimary [ [ AS ] alias ]
      [ WHERE booleanExpression ]

query:
      values
  |   WITH withItem [ , withItem ]* query
  |   {
          select
      |   selectWithoutFrom
      |   query UNION [ ALL | DISTINCT ] query
      |   query EXCEPT [ ALL | DISTINCT ] query
      |   query MINUS [ ALL | DISTINCT ] query
      |   query INTERSECT [ ALL | DISTINCT ] query
      }
      [ ORDER BY orderItem [, orderItem ]* ]
      [ LIMIT [ start, ] { count | ALL } ]
      [ OFFSET start { ROW | ROWS } ]
      [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY ]

withItem:
      name
      [ '(' column [, column ]* ')' ]
      AS '(' query ')'

orderItem:
      expression [ ASC | DESC ] [ NULLS FIRST | NULLS LAST ]

select:
      SELECT [ STREAM ] [ ALL | DISTINCT ]
          { * | projectItem [, projectItem ]* }
      FROM tableExpression
      [ WHERE booleanExpression ]
      [ GROUP BY { groupItem [, groupItem ]* } ]
      [ HAVING booleanExpression ]
      [ WINDOW windowName AS windowSpec [, windowName AS windowSpec ]* ]

selectWithoutFrom:
      SELECT [ ALL | DISTINCT ]
          { * | projectItem [, projectItem ]* }

projectItem:
      expression [ [ AS ] columnAlias ]
  |   tableAlias . *

tableExpression:
      tableReference [, tableReference ]*
  |   tableExpression [ NATURAL ] [ ( LEFT | RIGHT | FULL ) [ OUTER ] ] JOIN tableExpression [ joinCondition ]
  |   tableExpression CROSS JOIN tableExpression
  |   tableExpression [ CROSS | OUTER ] APPLY tableExpression

joinCondition:
      ON booleanExpression
  |   USING '(' column [, column ]* ')'

tableReference:
      tablePrimary
      [ matchRecognize ]
      [ [ AS ] alias [ '(' columnAlias [, columnAlias ]* ')' ] ]

tablePrimary:
      [ [ catalogName . ] schemaName . ] tableName
      '(' TABLE [ [ catalogName . ] schemaName . ] tableName ')'
  |   tablePrimary [ EXTEND ] '(' columnDecl [, columnDecl ]* ')'
  |   [ LATERAL ] '(' query ')'
  |   UNNEST '(' expression ')' [ WITH ORDINALITY ]
  |   [ LATERAL ] TABLE '(' [ SPECIFIC ] functionName '(' expression [, expression ]* ')' ')'

columnDecl:
      column type [ NOT NULL ]

values:
      VALUES expression [, expression ]*

groupItem:
      expression
  |   '(' ')'
  |   '(' expression [, expression ]* ')'
  |   CUBE '(' expression [, expression ]* ')'
  |   ROLLUP '(' expression [, expression ]* ')'
  |   GROUPING SETS '(' groupItem [, groupItem ]* ')'

windowRef:
      windowName
  |   windowSpec

windowSpec:
      [ windowName ]
      '('
      [ ORDER BY orderItem [, orderItem ]* ]
      [ PARTITION BY expression [, expression ]* ]
      [
          RANGE numericOrIntervalExpression { PRECEDING | FOLLOWING }
      |   ROWS numericExpression { PRECEDING | FOLLOWING }
      ]
      ')'

在insert中，如果insert或UPSERT语句没有指定目标列的列表，查询的列数必须与目标表相同，除非是在某些一致性级别。

在merge中，至少有一个匹配时和未匹配时的子句必须出现。

tablePrimary可能只包含特定符合性级别的扩展子句;在这些相同的一致性级别中，insert中的任何列都可以被columnDecl替换，其效果类似于将其包含在EXTEND子句中。

在orderItem中，如果表达式是正整数n，它表示SELECT子句中的第n项。

在查询中，count和start可以是无符号整型字面值，也可以是值为整型的动态参数。
aggregate聚合查询是包含GROUP BY或HAVING子句或SELECT子句中的聚合函数的查询。在SELECT中，具有和ORDER BY子句的聚合查询中，所有表达式都必须是当前组中的常量(即，按照group BY子句或常量的定义对常量进行分组)、聚合函数或常量与聚合函数的组合。聚合和分组函数只能出现在聚合查询中，而且只能出现在SELECT、HAVING或ORDER BY子句中。
标量子查询是用作表达式的子查询。如果子查询不返回行，则该值为空;如果它返回多个行，则为错误。

IN、EXISTS和scalar子查询可以出现在表达式的任何地方(例如SELECT子句、where子句、ON子句连接或聚合函数的参数)。

一个IN、EXISTS或scalar子查询可能相互关联;也就是说，它可以引用包含查询的FROM子句中的表。

selectWithoutFrom等价于值，但不是标准SQL，只允许在某些符合级别中使用。

MINUS相当于EXCEPT，但不是标准SQL，只允许在某些一致性级别上使用。

交叉应用和外部应用只允许在某些符合级别。

“限制开始，计数”相当于“限制计数偏移开始”，但只允许在某些符合级别。“LIMIT start, count” is equivalent to “LIMIT count OFFSET start” but is only allowed in certain conformance levels.

flink流计算随笔（8）

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