Merge #39543

39543: sql: More descriptive error messages in show partitions r=solongordon a=rohany

The show partitions statement suggests use of the index
hint syntax if the user does not use it.

Fixes #39476.

Release note: None

Co-authored-by: Rohan Yadav <[email protected]>

Author: craig[bot]

pkg/sql/delegate/show_partitions.go

@@ -15,7 +15,10 @@ import (
 
 	"github.com/cockroachdb/cockroach/pkg/sql/lex"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/cat"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/errors"
 )
 
 func (d *delegator) delegateShowPartitions(n *tree.ShowPartitions) (tree.Statement, error) {
@@ -89,6 +92,14 @@ func (d *delegator) delegateShowPartitions(n *tree.ShowPartitions) (tree.Stateme
 	flags := cat.Flags{AvoidDescriptorCaches: true, NoTableStats: true}
 	tn := n.Index.Table
 
+	// Throw a more descriptive error if the user did not use the index hint syntax.
+	if tn.TableName == "" {
+		err := errors.New("no table specified")
+		err = pgerror.WithCandidateCode(err, pgcode.InvalidParameterValue)
+		err = errors.WithHint(err, "Specify a table using the hint syntax of table@index")
+		return nil, err
+	}
+
 	dataSource, resName, err := d.catalog.ResolveDataSource(d.ctx, flags, &tn)
 	if err != nil {
 		return nil, err