Merge pull request #7367 from nvanbenschoten/nvanbenschoten/deallocate

sql: Add support for the DEALLOCATE statement

sql/executor.go

@@ -887,6 +887,17 @@ func (e *Executor) execStmtInOpenTxn(
 		}
 		txnState.updateStateAndCleanupOnErr(err, e)
 		return Result{Err: err}, err
+	case *parser.Deallocate:
+		if s.Name == "" {
+			planMaker.session.PreparedStatements.DeleteAll()
+		} else {
+			if found := planMaker.session.PreparedStatements.Delete(string(s.Name)); !found {
+				err := fmt.Errorf("prepared statement %s does not exist", s.Name)
+				txnState.updateStateAndCleanupOnErr(err, e)
+				return Result{Err: err}, err
+			}
+		}
+		return Result{PGTag: s.StatementTag()}, nil
 	}
 
 	if txnState.tr != nil {

sql/prepare.go

@@ -83,14 +83,24 @@ func (ps PreparedStatements) New(
 	return stmt, nil
 }
 
-// Delete removes the PreparedStatements with the provided name from the PreparedStatements.
-func (ps PreparedStatements) Delete(name string) {
+// Delete removes the PreparedStatement with the provided name from the PreparedStatements.
+// The method returns whether a statement with that name was found and removed.
+func (ps PreparedStatements) Delete(name string) bool {
 	if stmt, ok := ps.Get(name); ok {
 		for portalName := range stmt.portalNames {
 			delete(ps.session.PreparedPortals.portals, portalName)
 		}
 		delete(ps.stmts, name)
+		return true
 	}
+	return false
+}
+
+// DeleteAll removes all PreparedStatements from the PreparedStatements. This will in turn
+// remove all PreparedPortals from the session's PreparedPortals.
+func (ps PreparedStatements) DeleteAll() {
+	ps.stmts = make(map[string]*PreparedStatement)
+	ps.session.PreparedPortals.portals = make(map[string]*PreparedPortal)
 }
 
 // PreparedPortal is a PreparedStatement that has been bound with query arguments.
@@ -141,9 +151,12 @@ func (pp PreparedPortals) New(name string, stmt *PreparedStatement, qargs parser
 }
 
 // Delete removes the PreparedPortal with the provided name from the PreparedPortals.
-func (pp PreparedPortals) Delete(name string) {
+// The method returns whether a portal with that name was found and removed.
+func (pp PreparedPortals) Delete(name string) bool {
 	if portal, ok := pp.Get(name); ok {
 		delete(portal.Stmt.portalNames, name)
 		delete(pp.portals, name)
+		return true
 	}
+	return false
 }

sql/testdata/prepare

@@ -4,5 +4,10 @@ PREPARE a AS SELECT 1
 statement error unknown statement type: \*parser.Execute
 EXECUTE a
 
-statement error unknown statement type: \*parser.Deallocate
+# TODO(nvanbenschoten) This deserves more robust testing, but that is hard
+# to add until we support the PREPARE statement.
+statement error prepared statement a does not exist
 DEALLOCATE a
+
+statement ok
+DEALLOCATE ALL