A computer-executed method comprising: performing a refresh operation on a cloned pluggable database (250, 254), wherein said refresh operation utilizes redo records, recorded for a source pluggable database (220, 222), to incorporate, into the cloned pluggable database (250, 254), changes made to the source pluggable database (220, 222) that are not yet reflected in the cloned pluggable database (250, 254); wherein the source pluggable database (220, 222) is one of a plurality of first pluggable databases (220, 222) contained in a first container database, the first container database allowing computing resources to be shared between the plurality of first pluggable databases (220, 222); wherein the cloned pluggable database (250, 254) is one of a plurality of second pluggable databases (250, 252, 254) contained in a second container database, the second container database allowing computing resources to be shared between the plurality of second pluggable databases (250, 252, 254); while performing the refresh operation on the cloned pluggable database (250, 254), receiving a first query over the cloned pluggable database (250, 254); determining a logical timestamp, LT, for the first query based on a first LT service that is a PDB-specific LT service maintained for the cloned pluggable database (250, 254); wherein the LT for the first query indicates that all changes in the redo entries recorded at or before the LT for the first query have been applied to, and committed in, the cloned pluggable database (250, 254); wherein the first LT service maintained at least for the cloned pluggable database (250, 254) is distinct from a second LT service maintained for the second container database, wherein the second LT service is used to maintain ACID properties for transactions occurring in databases, within the second container database, that are not associated with any PDB-specific LT service; while performing the refresh operation, initiating execution of the first query over the cloned pluggable database (250, 254), wherein execution of the first query involves reading, from the cloned pluggable database (250, 254), particular data that is current as of the LT for the first query; receiving a second query over a second pluggable database contained in the second container database; determining a second LT for the second query based on the second LT service that is maintained for the second container database; and executing the second query over the second pluggable database based, at least in part, on the second LT; wherein the method is performed by one or more computing devices. performing a refresh operation on a cloned pluggable database (250, 254), wherein said refresh operation utilizes redo records, recorded for a source pluggable database (220, 222), to incorporate, into the cloned pluggable database (250, 254), changes made to the source pluggable database (220, 222) that are not yet reflected in the cloned pluggable database (250, 254); wherein the source pluggable database (220, 222) is one of a plurality of first pluggable databases (220, 222) contained in a first container database, the first container database allowing computing resources to be shared between the plurality of first pluggable databases (220, 222); wherein the cloned pluggable database (250, 254) is one of a plurality of second pluggable databases (250, 252, 254) contained in a second container database, the second container database allowing computing resources to be shared between the plurality of second pluggable databases (250, 252, 254); while performing the refresh operation on the cloned pluggable database (250, 254), receiving a first query over the cloned pluggable database (250, 254); determining a logical timestamp, LT, for the first query based on a first LT service that is a PDB-specific LT service maintained for the cloned pluggable database (250, 254); wherein the LT for the first query indicates that all changes in the redo entries recorded at or before the LT for the first query have been applied to, and committed in, the cloned pluggable database (250, 254); wherein the first LT service maintained at least for the cloned pluggable database (250, 254) is distinct from a second LT service maintained for the second container database, wherein the second LT service is used to maintain ACID properties for transactions occurring in databases, within the second container database, that are not associated with any PDB-specific LT service; while performing the refresh operation, initiating execution of the first query over the cloned pluggable database (250, 254), wherein execution of the first query involves reading, from the cloned pluggable database (250, 254), particular data that is current as of the LT for the first query; receiving a second query over a second pluggable database contained in the second container database; determining a second LT for the second query based on the second LT service that is maintained for the second container database; and executing the second query over the second pluggable database based, at least in part, on the second LT; wherein the method is performed by one or more computing devices.