sql: add support for EXPLAIN ANALYZE in SQL shell and a builtin

This commit fixes a possible crash that could happen whenever the
internal executor is used to run EXPLAIN ANALYZE statement (the crash
happened because we'd attempt to call `ResetStmtType` on
`streamingCommandResult` which is unimplemented). This commit makes this
method a no-op since we don't care about the stmt type. This affects the
UI SQL shell as well as `crdb_internal.execute_internally` builtin.

It additionally audits all methods of `streamingCommandResult` that
panic. `AddBatch` is ok to not be implemented given that we have
`SupportsBatch` always return `false`. Another panic is removed in
`BufferedResultsLen` (used under read committed) where it's ok to be
a no-op. This commit also moves the code around a bit to have better
layout.

Release note (sql change): EXPLAIN ANALYZE statements are now supported
when executed via UI SQL shell.

pkg/server/api_v2_sql_test.go

@@ -72,18 +72,12 @@ func TestExecSQL(t *testing.T) {
 			require.NoError(t, err)
 
 			if d.HasArg("expect-error") {
-				type jsonError struct {
-					Code    string `json:"code"`
-					Message string `json:"message"`
-				}
-				type errorResp struct {
-					Error jsonError `json:"error"`
-				}
-
-				er := errorResp{}
-				err := json.Unmarshal(r, &er)
-				require.NoError(t, err)
-				return fmt.Sprintf("%s|%s", er.Error.Code, er.Error.Message)
+				code, msg := getErrorResponse(t, r)
+				return fmt.Sprintf("%s|%s", code, msg)
+			} else if d.HasArg("expect-no-error") {
+				code, msg := getErrorResponse(t, r)
+				require.True(t, code == "" && msg == "", code, msg)
+				return ""
 			}
 			return getMarshalledResponse(t, r)
 		},
@@ -126,3 +120,18 @@ func getMarshalledResponse(t *testing.T, r []byte) string {
 	require.NoError(t, err)
 	return string(s)
 }
+
+func getErrorResponse(t *testing.T, r []byte) (code, message string) {
+	type jsonError struct {
+		Code    string `json:"code"`
+		Message string `json:"message"`
+	}
+	type errorResp struct {
+		Error jsonError `json:"error"`
+	}
+
+	er := errorResp{}
+	err := json.Unmarshal(r, &er)
+	require.NoError(t, err)
+	return er.Error.Code, er.Error.Message
+}

pkg/server/testdata/api_v2_sql

@@ -1062,3 +1062,12 @@ sql admin
  },
  "num_statements": 4
 }
+
+# Note that we don't verify the contents of the response because it's not
+# deterministic, so we only check that it didn't result in an error.
+sql admin expect-no-error
+{
+  "execute": true,
+  "statements": [{"sql": "EXPLAIN ANALYZE SELECT 1"}]
+}
+----

pkg/sql/conn_io.go

@@ -868,18 +868,18 @@ type RestrictedCommandResult interface {
 	// soon as AddBatch returns.
 	AddBatch(ctx context.Context, batch coldata.Batch) error
 
+	// SupportsAddBatch returns whether this command result supports AddBatch
+	// method of adding the data. If false is returned, then the behavior of
+	// AddBatch is undefined.
+	SupportsAddBatch() bool
+
 	// BufferedResultsLen returns the length of the results buffer.
 	BufferedResultsLen() int
 
 	// TruncateBufferedResults clears any results that have been buffered after
 	// given index, and returns true iff any results were actually truncated.
 	TruncateBufferedResults(idx int) bool
 
-	// SupportsAddBatch returns whether this command result supports AddBatch
-	// method of adding the data. If false is returned, then the behavior of
-	// AddBatch is undefined.
-	SupportsAddBatch() bool
-
 	// SetRowsAffected sets RowsAffected counter to n. This is used for all
 	// result types other than tree.Rows.
 	SetRowsAffected(ctx context.Context, n int)
@@ -1120,7 +1120,8 @@ func (r *streamingCommandResult) SendNotice(ctx context.Context, notice pgnotice
 
 // ResetStmtType is part of the RestrictedCommandResult interface.
 func (r *streamingCommandResult) ResetStmtType(stmt tree.Statement) {
-	panic("unimplemented")
+	// This command result doesn't care about the stmt type since it doesn't
+	// produce pgwire messages.
 }
 
 // GetFormatCode is part of the sql.RestrictedCommandResult interface.
@@ -1150,23 +1151,24 @@ func (r *streamingCommandResult) AddBatch(context.Context, coldata.Batch) error
 	panic("unimplemented")
 }
 
+// SupportsAddBatch is part of the RestrictedCommandResult interface.
+func (r *streamingCommandResult) SupportsAddBatch() bool {
+	return false
+}
+
 // BufferedResultsLen is part of the RestrictedCommandResult interface.
 func (r *streamingCommandResult) BufferedResultsLen() int {
-	// Since this implementation is streaming, there is no sensible return
-	// value here.
-	panic("unimplemented")
+	// Since this implementation is streaming, we cannot truncate some buffered
+	// results. This is achieved by unconditionally returning false in
+	// TruncateBufferedResults, so this return value doesn't actually matter.
+	return 0
 }
 
 // TruncateBufferedResults is part of the RestrictedCommandResult interface.
 func (r *streamingCommandResult) TruncateBufferedResults(int) bool {
 	return false
 }
 
-// SupportsAddBatch is part of the RestrictedCommandResult interface.
-func (r *streamingCommandResult) SupportsAddBatch() bool {
-	return false
-}
-
 func (r *streamingCommandResult) DisableBuffering() {
 	panic("cannot disable buffering here")
 }

pkg/sql/opt/exec/execbuilder/testdata/execute_internally_builtin

@@ -212,3 +212,6 @@ query T
 SELECT crdb_internal.execute_internally('SELECT session_user;', 'User=testuser');
 ----
 root
+
+statement ok
+SELECT crdb_internal.execute_internally('EXPLAIN ANALYZE SELECT 1;');

pkg/sql/pgwire/command_result.go

@@ -287,6 +287,11 @@ func (r *commandResult) AddBatch(ctx context.Context, batch coldata.Batch) error
 	return r.conn.bufferBatch(ctx, batch, r)
 }
 
+// SupportsAddBatch is part of the sql.RestrictedCommandResult interface.
+func (r *commandResult) SupportsAddBatch() bool {
+	return true
+}
+
 // BufferedResultsLen is part of the sql.RestrictedCommandResult interface.
 func (r *commandResult) BufferedResultsLen() int {
 	return r.conn.writerState.buf.Len()
@@ -308,11 +313,6 @@ func (r *commandResult) TruncateBufferedResults(idx int) bool {
 	return true
 }
 
-// SupportsAddBatch is part of the sql.RestrictedCommandResult interface.
-func (r *commandResult) SupportsAddBatch() bool {
-	return true
-}
-
 // DisableBuffering is part of the sql.RestrictedCommandResult interface.
 func (r *commandResult) DisableBuffering() {
 	r.assertNotReleased()
@@ -560,18 +560,18 @@ func (r *limitedCommandResult) AddRow(ctx context.Context, row tree.Datums) erro
 	return nil
 }
 
-// RevokePortalPausability is part of the sql.RestrictedCommandResult interface.
-func (r *limitedCommandResult) RevokePortalPausability() error {
-	r.portalPausablity = sql.NotPausablePortalForUnsupportedStmt
-	return nil
-}
-
 // SupportsAddBatch is part of the sql.RestrictedCommandResult interface.
 // TODO(yuzefovich): implement limiting behavior for AddBatch.
 func (r *limitedCommandResult) SupportsAddBatch() bool {
 	return false
 }
 
+// RevokePortalPausability is part of the sql.RestrictedCommandResult interface.
+func (r *limitedCommandResult) RevokePortalPausability() error {
+	r.portalPausablity = sql.NotPausablePortalForUnsupportedStmt
+	return nil
+}
+
 // moreResultsNeeded is a restricted connection handler that waits for more
 // requests for rows from the active portal, during the "execute portal" flow
 // when a limit has been specified.