Add IF EXISTS support to DROP TABLE and DROP VIEW

presto-docs/src/main/sphinx/release/release-0.101.rst

@@ -6,6 +6,7 @@ General Changes
 ---------------
 
 * Add support for :doc:`/sql/create-table` (in addition to :doc:`/sql/create-table-as`).
+* Add `IF EXISTS` support to :doc:`/sql/drop-table` and :doc:`/sql/drop-view`.
 * Add :func:`array_agg` function.
 * Add :func:`array_intersect` function.
 * Add :func:`regexp_split` function.

presto-docs/src/main/sphinx/sql/drop-table.rst

@@ -7,17 +7,24 @@ Synopsis
 
 .. code-block:: none
 
- DROP TABLE table_name
+ DROP TABLE  [ IF EXISTS ] table_name
 
 Description
 -----------
 
-Drops an existing table
+Drops an existing table.
+
+The optional ``IF EXISTS`` clause causes the error to be suppressed if
+the table does not exist.
 
 Examples
 --------
 
-Drop a table ``orders_by_date``::
+Drop the table ``orders_by_date``::
 
  DROP TABLE orders_by_date
 
+Drop the table ``orders_by_date`` if it exists::
+
+ DROP TABLE IF EXISTS orders_by_date
+

presto-docs/src/main/sphinx/sql/drop-view.rst

@@ -7,16 +7,23 @@ Synopsis
 
 .. code-block:: none
 
- DROP VIEW view_name
+ DROP VIEW [ IF EXISTS ] view_name
 
 Description
 -----------
 
 Drop an existing view.
 
+The optional ``IF EXISTS`` clause causes the error to be suppressed if
+the view does not exist.
+
 Examples
 --------
 
 Drop the view ``orders_by_date``::
 
  DROP VIEW orders_by_date
+
+Drop the view ``orders_by_date`` if it exists::
+
+ DROP VIEW IF EXISTS orders_by_date

presto-main/src/main/java/com/facebook/presto/execution/DropTableTask.java

@@ -41,7 +41,10 @@ public void execute(DropTable statement, Session session, Metadata metadata, Que
 
  Optional<TableHandle> tableHandle = metadata.getTableHandle(session, tableName);
  if (!tableHandle.isPresent()) {
- throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+ if (!statement.isExists()) {
+ throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+ }
+ return;
  }
 
  metadata.dropTable(tableHandle.get());

presto-main/src/main/java/com/facebook/presto/execution/DropViewTask.java

@@ -41,7 +41,10 @@ public void execute(DropView statement, Session session, Metadata metadata, Quer
 
  Optional<ViewDefinition> view = metadata.getView(session, name);
  if (!view.isPresent()) {
- throw new SemanticException(MISSING_TABLE, statement, "View '%s' does not exist", name);
+ if (!statement.isExists()) {
+ throw new SemanticException(MISSING_TABLE, statement, "View '%s' does not exist", name);
+ }
+ return;
  }
 
  metadata.dropView(session, name);

presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4

@@ -33,11 +33,11 @@ statement
  | CREATE TABLE qualifiedName AS query #createTableAsSelect
  | CREATE TABLE qualifiedName
  '(' tableElement (',' tableElement)* ')' #createTable
- | DROP TABLE qualifiedName  #dropTable
+ | DROP TABLE (IF EXISTS)? qualifiedName #dropTable
  | INSERT INTO qualifiedName query #insertInto
  | ALTER TABLE from=qualifiedName RENAME TO to=qualifiedName #renameTable
  | CREATE (OR REPLACE)? VIEW qualifiedName AS query #createView
- | DROP VIEW qualifiedName  #dropView
+ | DROP VIEW (IF EXISTS)? qualifiedName #dropView
  | EXPLAIN ('(' explainOption (',' explainOption)* ')')? statement #explain
  | SHOW TABLES ((FROM | IN) qualifiedName)? (LIKE pattern=STRING)? #showTables
  | SHOW SCHEMAS ((FROM | IN) identifier)? #showSchemas

presto-parser/src/main/java/com/facebook/presto/sql/SqlFormatter.java

@@ -447,8 +447,11 @@ protected Void visitCreateView(CreateView node, Integer indent)
  @Override
  protected Void visitDropView(DropView node, Integer context)
  {
- builder.append("DROP VIEW ")
- .append(node.getName());
+ builder.append("DROP VIEW ");
+ if (node.isExists()) {
+ builder.append("IF EXISTS ");
+ }
+ builder.append(node.getName());
 
  return null;
  }
@@ -600,8 +603,11 @@ protected Void visitCreateTable(CreateTable node, Integer indent)
  @Override
  protected Void visitDropTable(DropTable node, Integer context)
  {
- builder.append("DROP TABLE ")
- .append(node.getTableName());
+ builder.append("DROP TABLE ");
+ if (node.isExists()) {
+ builder.append("IF EXISTS ");
+ }
+ builder.append(node.getTableName());
 
  return null;
  }

presto-parser/src/main/java/com/facebook/presto/sql/parser/AstBuilder.java

@@ -156,13 +156,13 @@ public Node visitCreateTable(@NotNull SqlBaseParser.CreateTableContext context)
  @Override
  public Node visitDropTable(@NotNull SqlBaseParser.DropTableContext context)
  {
- return new DropTable(getQualifiedName(context.qualifiedName()));
+ return new DropTable(getQualifiedName(context.qualifiedName()), context.EXISTS() != null);
  }
 
  @Override
  public Node visitDropView(@NotNull SqlBaseParser.DropViewContext context)
  {
- return new DropView(getQualifiedName(context.qualifiedName()));
+ return new DropView(getQualifiedName(context.qualifiedName()), context.EXISTS() != null);
  }
 
  @Override

presto-parser/src/main/java/com/facebook/presto/sql/tree/DropTable.java

@@ -21,17 +21,24 @@ public class DropTable
  extends Statement
 {
  private final QualifiedName tableName;
+ private final boolean exists;
 
- public DropTable(QualifiedName tableName)
+ public DropTable(QualifiedName tableName, boolean exists)
  {
  this.tableName = tableName;
+ this.exists = exists;
  }
 
  public QualifiedName getTableName()
  {
  return tableName;
  }
 
+ public boolean isExists()
+ {
+ return exists;
+ }
+
  @Override
  public <R, C> R accept(AstVisitor<R, C> visitor, C context)
  {
@@ -41,7 +48,7 @@ public <R, C> R accept(AstVisitor<R, C> visitor, C context)
  @Override
  public int hashCode()
  {
- return Objects.hash(tableName);
+ return Objects.hash(tableName, exists);
  }
 
  @Override
@@ -54,14 +61,16 @@ public boolean equals(Object obj)
  return false;
  }
  DropTable o = (DropTable) obj;
- return Objects.equals(tableName, o.tableName);
+ return Objects.equals(tableName, o.tableName)
+ && (exists == o.exists);
  }
 
  @Override
  public String toString()
  {
  return toStringHelper(this)
  .add("tableName", tableName)
+ .add("exists", exists)
  .toString();
  }
 }

presto-parser/src/main/java/com/facebook/presto/sql/tree/DropView.java

@@ -21,17 +21,24 @@ public class DropView
  extends Statement
 {
  private final QualifiedName name;
+ private final boolean exists;
 
- public DropView(QualifiedName name)
+ public DropView(QualifiedName name, boolean exists)
  {
  this.name = name;
+ this.exists = exists;
  }
 
  public QualifiedName getName()
  {
  return name;
  }
 
+ public boolean isExists()
+ {
+ return exists;
+ }
+
  @Override
  public <R, C> R accept(AstVisitor<R, C> visitor, C context)
  {
@@ -41,7 +48,7 @@ public <R, C> R accept(AstVisitor<R, C> visitor, C context)
  @Override
  public int hashCode()
  {
- return Objects.hash(name);
+ return Objects.hash(name, exists);
  }
 
  @Override
@@ -54,14 +61,16 @@ public boolean equals(Object obj)
  return false;
  }
  DropView o = (DropView) obj;
- return Objects.equals(name, o.name);
+ return Objects.equals(name, o.name)
+ && (exists == o.exists);
  }
 
  @Override
  public String toString()
  {
  return toStringHelper(this)
  .add("name", name)
+ .add("exists", exists)
  .toString();
  }
 }

presto-parser/src/test/java/com/facebook/presto/sql/parser/TestSqlParser.java

@@ -667,18 +667,26 @@ public void testCreateTableAsSelect()
  public void testDropTable()
  throws Exception
  {
- assertStatement("DROP TABLE a", new DropTable(QualifiedName.of("a")));
- assertStatement("DROP TABLE a.b", new DropTable(QualifiedName.of("a", "b")));
- assertStatement("DROP TABLE a.b.c", new DropTable(QualifiedName.of("a", "b", "c")));
+ assertStatement("DROP TABLE a", new DropTable(QualifiedName.of("a"), false));
+ assertStatement("DROP TABLE a.b", new DropTable(QualifiedName.of("a", "b"), false));
+ assertStatement("DROP TABLE a.b.c", new DropTable(QualifiedName.of("a", "b", "c"), false));
+
+ assertStatement("DROP TABLE IF EXISTS a", new DropTable(QualifiedName.of("a"), true));
+ assertStatement("DROP TABLE IF EXISTS a.b", new DropTable(QualifiedName.of("a", "b"), true));
+ assertStatement("DROP TABLE IF EXISTS a.b.c", new DropTable(QualifiedName.of("a", "b", "c"), true));
  }
 
  @Test
  public void testDropView()
  throws Exception
  {
- assertStatement("DROP VIEW a", new DropView(QualifiedName.of("a")));
- assertStatement("DROP VIEW a.b", new DropView(QualifiedName.of("a", "b")));
- assertStatement("DROP VIEW a.b.c", new DropView(QualifiedName.of("a", "b", "c")));
+ assertStatement("DROP VIEW a", new DropView(QualifiedName.of("a"), false));
+ assertStatement("DROP VIEW a.b", new DropView(QualifiedName.of("a", "b"), false));
+ assertStatement("DROP VIEW a.b.c", new DropView(QualifiedName.of("a", "b", "c"), false));
+
+ assertStatement("DROP VIEW IF EXISTS a", new DropView(QualifiedName.of("a"), true));
+ assertStatement("DROP VIEW IF EXISTS a.b", new DropView(QualifiedName.of("a", "b"), true));
+ assertStatement("DROP VIEW IF EXISTS a.b.c", new DropView(QualifiedName.of("a", "b", "c"), true));
  }
 
  @Test

presto-tests/src/main/java/com/facebook/presto/tests/AbstractTestDistributedQueries.java

@@ -183,6 +183,15 @@ public void testInsert()
  assertQueryTrue("DROP TABLE test_insert");
  }
 
+ @Test
+ public void testDropTableIfExists()
+ throws Exception
+ {
+ assertFalse(queryRunner.tableExists(getSession(), "test_drop_if_exists"));
+ assertQueryTrue("DROP TABLE IF EXISTS test_create");
+ assertFalse(queryRunner.tableExists(getSession(), "test_drop_if_exists"));
+ }
+
  @Test
  public void testView()
  throws Exception