UniStore: Use epoch with microsecond resolution as RV (#92638)

* Use epoch with microsecond resolution as RV

* fix backend tests

* Add solution for when the clock goes back

* Add solution for when the clock goes back

* generate mocks

* go lint

* remove comment

* Use Greatest instead of max in msyql and postgres

* update tests

* Update pkg/storage/unified/sql/sqltemplate/dialect_sqlite.go

Co-authored-by: Diego Augusto Molina <diegoaugustomolina@gmail.com>

* cast to bigint

* add additional round trip

* increment the RV using 2 sql round trips instead of 3

* cleanup comments

* cast unix timestamp to integer

* fix postgres query

* remove old increment test data

* remove greatest

* cast unix_timestamp to signed

* Use statement_timestamp instead of clock_timestamp

---------

Co-authored-by: Diego Augusto Molina <diegoaugustomolina@gmail.com>

pkg/storage/unified/sql/queries.go

@@ -41,7 +41,7 @@ var (
 
 	// sqlResourceLabelsInsert = mustTemplate("resource_labels_insert.sql")
 	sqlResourceVersionGet    = mustTemplate("resource_version_get.sql")
-	sqlResourceVersionInc    = mustTemplate("resource_version_inc.sql")
+	sqlResourceVersionUpdate = mustTemplate("resource_version_update.sql")
 	sqlResourceVersionInsert = mustTemplate("resource_version_insert.sql")
 	sqlResourceVersionList   = mustTemplate("resource_version_list.sql")
 )
@@ -191,8 +191,13 @@ func (r sqlResourceUpdateRVRequest) Validate() error {
 }
 
 // resource_version table requests.
-type resourceVersion struct {
+type resourceVersionResponse struct {
 	ResourceVersion int64
+	CurrentEpoch    int64
+}
+
+func (r *resourceVersionResponse) Results() (*resourceVersionResponse, error) {
+	return r, nil
 }
 
 type groupResourceVersion struct {
@@ -200,20 +205,32 @@ type groupResourceVersion struct {
 	ResourceVersion int64
 }
 
-func (r *resourceVersion) Results() (*resourceVersion, error) {
-	return r, nil
+type sqlResourceVersionUpsertRequest struct {
+	sqltemplate.SQLTemplate
+	Group, Resource string
+	ResourceVersion int64
 }
 
-type sqlResourceVersionRequest struct {
+func (r sqlResourceVersionUpsertRequest) Validate() error {
+	return nil // TODO
+}
+
+type sqlResourceVersionGetRequest struct {
 	sqltemplate.SQLTemplate
 	Group, Resource string
 	ReadOnly        bool
-	*resourceVersion
+	Response        *resourceVersionResponse
 }
 
-func (r sqlResourceVersionRequest) Validate() error {
+func (r sqlResourceVersionGetRequest) Validate() error {
 	return nil // TODO
 }
+func (r sqlResourceVersionGetRequest) Results() (*resourceVersionResponse, error) {
+	return &resourceVersionResponse{
+		ResourceVersion: r.Response.ResourceVersion,
+		CurrentEpoch:    r.Response.CurrentEpoch,
+	}, nil
+}
 
 type sqlResourceVersionListRequest struct {
 	sqltemplate.SQLTemplate