jobs: add tracing spans to update and load job

Here we start child tracing spans during update and load job
operations. These seems like the two most interesting operations from
the pespective of resumers.

Release note: None

pkg/jobs/jobs.go

@@ -35,6 +35,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
 	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
+	"github.com/cockroachdb/cockroach/pkg/util/tracing"
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/redact"
 	"github.com/gogo/protobuf/jsonpb"
@@ -798,6 +799,9 @@ func HasJobNotFoundError(err error) bool {
 }
 
 func (j *Job) load(ctx context.Context, txn *kv.Txn) error {
+	ctx, sp := tracing.ChildSpan(ctx, "load-job")
+	defer sp.Finish()
+
 	var payload *jobspb.Payload
 	var progress *jobspb.Progress
 	var createdBy *CreatedByInfo

pkg/jobs/update.go

@@ -27,6 +27,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
+	"github.com/cockroachdb/cockroach/pkg/util/tracing"
 	"github.com/cockroachdb/errors"
 )
 
@@ -140,6 +141,9 @@ func (j *Job) Update(ctx context.Context, txn *kv.Txn, updateFn UpdateFn) error
 }
 
 func (j *Job) update(ctx context.Context, txn *kv.Txn, useReadLock bool, updateFn UpdateFn) error {
+	ctx, sp := tracing.ChildSpan(ctx, "update-job")
+	defer sp.Finish()
+
 	var payload *jobspb.Payload
 	var progress *jobspb.Progress
 	var status Status
@@ -150,7 +154,7 @@ func (j *Job) update(ctx context.Context, txn *kv.Txn, useReadLock bool, updateF
 		var err error
 		var row tree.Datums
 		row, err = j.registry.ex.QueryRowEx(
-			ctx, "log-job", txn,
+			ctx, "select-job", txn,
 			sessiondata.InternalExecutorOverride{User: username.RootUserName()},
 			getSelectStmtForJobUpdate(j.session != nil, useReadLock), j.ID(),
 		)