AstBuilder — ANTLR-based SQL Parser¶

AstBuilder converts ANTLR ParseTrees into Catalyst entities using visit callbacks.

AstBuilder is the only requirement of the AbstractSqlParser abstraction (and used by CatalystSqlParser directly while SparkSqlParser uses SparkSqlAstBuilder instead).

SqlBase.g4 — ANTLR Grammar¶

AstBuilder is a ANTLR AbstractParseTreeVisitor (as SqlBaseBaseVisitor) that is generated from the ANTLR grammar of Spark SQL.

SqlBaseBaseVisitor is a ANTLR-specific base class that is generated at build time from the ANTLR grammar of Spark SQL is available in the Apache Spark repository at SqlBase.g4.

SqlBaseBaseVisitor is an AbstractParseTreeVisitor in ANTLR.

Visit Callbacks¶

visitAnalyze¶

Creates an AnalyzeColumnStatement or an AnalyzeTableStatement logical operator

ANALYZE TABLE multipartIdentifier partitionSpec? COMPUTE STATISTICS
  (identifier | FOR COLUMNS identifierSeq | FOR ALL COLUMNS)?

ANTLR labeled alternative: #analyze

visitDeleteFromTable¶

Creates a DeleteFromTable

ANTLR labeled alternative: #deleteFromTable

visitDescribeRelation¶

Creates a DescribeColumnStatement or DescribeRelation

(DESC | DESCRIBE) TABLE? option=(EXTENDED | FORMATTED)?
  multipartIdentifier partitionSpec? describeColName?

ANTLR labeled alternative: #describeRelation

visitExists¶

Creates an Exists expression

ANTLR labeled alternative: #exists

visitExplain¶

Creates a ExplainCommand

ANTLR rule: explain

visitFirst¶

Creates a First aggregate function expression

FIRST '(' expression (IGNORE NULLS)? ')'

ANTLR labeled alternative: #first

visitFromClause¶

Creates a LogicalPlan

Supports multiple comma-separated relations (that all together build a condition-less INNER JOIN) with optional LATERAL VIEW.

A relation can be one of the following or a combination thereof:

• Table identifier
• Inline table using VALUES exprs AS tableIdent
• Table-valued function (currently only range is supported)

ANTLR rule: fromClause

visitFunctionCall¶

Creates one of the following:

• UnresolvedFunction for a bare function (with no window specification)

• UnresolvedWindowExpression for a function evaluated in a windowed context with a WindowSpecReference

• WindowExpression for a function over a window

ANTLR rule: functionCall

import spark.sessionState.sqlParser

scala> sqlParser.parseExpression("foo()")
res0: org.apache.spark.sql.catalyst.expressions.Expression = 'foo()

scala> sqlParser.parseExpression("foo() OVER windowSpecRef")
res1: org.apache.spark.sql.catalyst.expressions.Expression = unresolvedwindowexpression('foo(), WindowSpecReference(windowSpecRef))

scala> sqlParser.parseExpression("foo() OVER (CLUSTER BY field)")
res2: org.apache.spark.sql.catalyst.expressions.Expression = 'foo() windowspecdefinition('field, UnspecifiedFrame)

visitInlineTable¶

Creates a UnresolvedInlineTable unary logical operator (as the child of SubqueryAlias for tableAlias)

VALUES expression (',' expression)* tableAlias

expression can be as follows:

• CreateNamedStruct expression for multiple-column tables

• Any Catalyst expression for one-column tables

tableAlias can be specified explicitly or defaults to colN for every column (starting from 1 for N).

ANTLR rule: inlineTable

visitInsertIntoTable¶

Creates a InsertIntoTable (indirectly)

A 3-element tuple with a TableIdentifier, optional partition keys and the exists flag disabled

INSERT INTO TABLE? tableIdentifier partitionSpec?

ANTLR labeled alternative: #insertIntoTable

visitInsertOverwriteTable¶

Creates a InsertIntoTable (indirectly)

A 3-element tuple with a TableIdentifier, optional partition keys and the exists flag

INSERT OVERWRITE TABLE tableIdentifier (partitionSpec (IF NOT EXISTS)?)?

In a way, visitInsertOverwriteTable is simply a more general version of the visitInsertIntoTable with the exists flag on or off based on existence of IF NOT EXISTS. The main difference is that dynamic partitions are used with no IF NOT EXISTS.

ANTLR labeled alternative: #insertOverwriteTable

visitMergeIntoTable¶

Creates a MergeIntoTable

ANTLR labeled alternative: #mergeIntoTable

visitMultiInsertQuery¶

Creates a logical operator with a InsertIntoTable (and UnresolvedRelation leaf operator)

FROM relation (',' relation)* lateralView*
INSERT OVERWRITE TABLE ...

FROM relation (',' relation)* lateralView*
INSERT INTO TABLE? ...

ANTLR rule: multiInsertQueryBody

visitNamedExpression¶

Creates one of the following Catalyst expressions:

• Alias (for a single alias)
• MultiAlias (for a parenthesis enclosed alias list)
• a bare Expression

ANTLR rule: namedExpression

visitNamedQuery¶

Creates a SubqueryAlias

visitQuerySpecification¶

Creates OneRowRelation or LogicalPlan

val q = sql("select 1")
scala> println(q.queryExecution.logical.numberedTreeString)
00 'Project [unresolvedalias(1, None)]
01 +- OneRowRelation$

ANTLR rule: querySpecification

visitPredicated¶

Creates an Expression

ANTLR rule: predicated

visitRelation¶

Creates a LogicalPlan for a FROM clause.

ANTLR rule: relation

visitRepairTable¶

Creates a RepairTableStatement for the following SQL statement:

MSCK REPAIR TABLE multipartIdentifier

ANTLR labeled alternative: #repairTable

visitShowCurrentNamespace¶

Creates a ShowCurrentNamespaceStatement for the following SQL statement:

SHOW CURRENT NAMESPACE

ANTLR labeled alternative: #showCurrentNamespace

visitShowTables¶

Creates a ShowTables for the following SQL statement:

SHOW TABLES ((FROM | IN) multipartIdentifier)?
  (LIKE? pattern=STRING)?

ANTLR labeled alternative: #showTables

visitSingleDataType¶

Creates a DataType

ANTLR rule: singleDataType

visitSingleExpression¶

Creates an Expression

Takes the named expression and relays to visitNamedExpression

ANTLR rule: singleExpression

visitSingleInsertQuery¶

Creates a LogicalPlan with a InsertIntoTable

INSERT INTO TABLE? tableIdentifier partitionSpec? #insertIntoTable

INSERT OVERWRITE TABLE tableIdentifier (partitionSpec (IF NOT EXISTS)?)? #insertOverwriteTable

ANTLR labeled alternative: #singleInsertQuery

visitSortItem¶

Creates a SortOrder unary expression

sortItem
    : expression ordering=(ASC | DESC)? (NULLS nullOrder=(LAST | FIRST))?
    ;

// queryOrganization
ORDER BY order+=sortItem (',' order+=sortItem)*
SORT BY sort+=sortItem (',' sort+=sortItem)*

// windowSpec
(ORDER | SORT) BY sortItem (',' sortItem)*)?

ANTLR rule: sortItem

visitSingleStatement¶

Creates a LogicalPlan from a single SQL statement

ANTLR rule: singleStatement

visitStar¶

Creates a UnresolvedStar

ANTLR labeled alternative: #star

visitSubqueryExpression¶

Creates a ScalarSubquery

ANTLR labeled alternative: #subqueryExpression

visitUse¶

Creates a UseStatement for the following SQL statement:

USE NAMESPACE? multipartIdentifier

ANTLR labeled alternative: #use

visitWindowDef¶

Creates a WindowSpecDefinition

// CLUSTER BY with window frame
'(' CLUSTER BY partition+=expression (',' partition+=expression)*) windowFrame? ')'

// PARTITION BY and ORDER BY with window frame
'(' ((PARTITION | DISTRIBUTE) BY partition+=expression (',' partition+=expression)*)?
  ((ORDER | SORT) BY sortItem (',' sortItem)*)?)
  windowFrame? ')'

ANTLR rule: windowDef

Parsing Handlers¶

withAggregationClause¶

withAggregationClause(
  ctx: AggregationClauseContext,
  selectExpressions: Seq[NamedExpression],
  query: LogicalPlan): LogicalPlan

Adds one of the following logical operators:

• GroupingSets for GROUP BY … GROUPING SETS (…)

• Aggregate for GROUP BY … (WITH CUBE | WITH ROLLUP)?

withGenerate¶

Adds a Generate with a UnresolvedGenerator and join flag enabled for LATERAL VIEW (in SELECT or FROM clauses).

withHavingClause¶

withHavingClause(
  ctx: HavingClauseContext,
  plan: LogicalPlan): LogicalPlan

Creates an UnresolvedHaving

withHints¶

Adds a Hint for /*+ hint */ in SELECT queries.

hint is of the format name or name (param1, param2, ...).

/*+ BROADCAST (table) */

withInsertInto¶

Creates one of the following logical operators:

• InsertIntoStatement
• InsertIntoDir

withInsertInto is used for visitMultiInsertQuery and visitSingleInsertQuery

withJoinRelations¶

Adds a Join for a FROM clause and relation alone.

The following join types are supported:

• INNER (default)
• CROSS
• LEFT (with optional OUTER)
• LEFT SEMI
• RIGHT (with optional OUTER)
• FULL (with optional OUTER)
• ANTI (optionally prefixed with LEFT)

The following join criteria are supported:

• ON booleanExpression
• USING '(' identifier (',' identifier)* ')'

Joins can be NATURAL (with no join criteria)

withQuerySpecification¶

Adds a query specification to a logical operator

For transform SELECT (with TRANSFORM, MAP or REDUCE qualifiers), withQuerySpecification does...FIXME

For regular SELECT (no TRANSFORM, MAP or REDUCE qualifiers), withQuerySpecification adds (in that order):

. Generate unary logical operators (if used in the parsed SQL text)

. Filter unary logical plan (if used in the parsed SQL text)

. GroupingSets or Aggregate unary logical operators (if used in the parsed SQL text)

. Project and/or Filter unary logical operators

. WithWindowDefinition unary logical operator (if used in the parsed SQL text)

. UnresolvedHint unary logical operator (if used in the parsed SQL text)

withPredicate¶

• NOT? IN '(' query ')' adds an In predicate expression with a ListQuery subquery expression

• NOT? IN '(' expression (',' expression)* ')' adds an In predicate expression

withQueryResultClauses¶

withRepartitionByExpression¶

withRepartitionByExpression(
  ctx: QueryOrganizationContext,
  expressions: Seq[Expression],
  query: LogicalPlan): LogicalPlan

withRepartitionByExpression simply throws a ParseException:

DISTRIBUTE BY is not supported

withRepartitionByExpression is used when AstBuilder is requested to withQueryResultClauses (for DISTRIBUTE BY and CLUSTER BY SQL clauses).

withSample¶

withSelectQuerySpecification¶

withWindows¶

Adds a WithWindowDefinition for window aggregates (given WINDOW definitions).

Used for withQueryResultClauses and withQuerySpecification with windows definition.

WINDOW identifier AS windowSpec
  (',' identifier AS windowSpec)*

aliasPlan Method¶

aliasPlan(
  alias: ParserRuleContext,
  plan: LogicalPlan): LogicalPlan

aliasPlan...FIXME

aliasPlan is used when...FIXME

mayApplyAliasPlan Method¶

mayApplyAliasPlan(
  tableAlias: TableAliasContext,
  plan: LogicalPlan): LogicalPlan

mayApplyAliasPlan...FIXME

mayApplyAliasPlan is used when...FIXME