Systems and methods for a distributed database to transition between centralized transaction management and global clock transaction management with little to no downtime

A method for an online transaction system to transition from operating under a first mode where a plurality of transactions nodes identify sequential transactions with sequential identification numbers obtained from a global transaction server (GTS) to a second mode where the plurality of transaction nodes identify consecutive transactions with timestamps based on global clock servers (GCSs) coupled to the transaction nodes, the method comprising:

• at a transaction node of the plurality of transaction nodes:
• receiving a command to operate under a transition mode;
• when in the transition mode,
• obtaining, for a transaction conducted at the transaction node, a timestamp (ts) and a timestamp error bound (eb), the ts and the eb being based on the GCSs;
• providing ts and eb to the GTS operating under the transition mode;
• receiving from the GTS a modified timestamp (ts_reply) and a modified error bound (eb′);
• timestamping the transaction with ts_reply;
• and
• waiting for a time interval of eb′ prior to providing any further timestamp and timestamp error bound to the GTS.

A method for an online transaction system to transition from operating under a first mode where transaction nodes identify consecutive transactions with timestamps based on global clock servers (GCSs) coupled to the transaction nodes, to operating under a second mode where the transactions nodes identify sequential transactions with sequential identification numbers obtained from a global transaction server (GTS), the method comprising:

• at the GTS:
• receiving a command to switch from operating under the first mode to operating under a transition mode;
• when the GTS is operating under the transition mode:
• for a transaction initiated after the GTS switched to operating under the transition mode:
• receiving a transaction timestamp (ts) and an error bound (eb) of the timestamp from a transaction node, the ts and the eb being based on the GCSs, the GTS having associated thereto:
• an identification number of a last transaction conducted by the GTS,
• timestamps previously received (previous_tss) at the GTS, and
• error bounds of the timestamps previously received (previous_ebs) at the GTS;
• obtaining a modified timestamp (ts_reply) by determining a maximum value between the ts, the previous_tss, and the identification number of the last transaction incremented by a pre-determined increment value;
• determining a modified error bound (eb′) by adding the eb to a difference between ts_reply and ts;
• and
• providing the ts_reply and the eb′ to the transaction node that provided the ts and the eb to the GTS to cause the transaction node to timestamp the transaction with ts_reply, and to wait for a duration of eb′ before requesting any further timestamp.

A method for an online transaction system to transition from operating under a first mode where transaction nodes identify consecutive transactions with timestamps based on global clock servers (GCSs) coupled to the transaction nodes, to operating under a second mode where the transactions nodes identify sequential transactions with sequential identification numbers obtained from a global transaction server (GTS), the method comprising:

• at a controller coupled to the transaction nodes and to the GTS:
• instructing the transaction nodes and the GTS to operate under a transition mode;
• and
• after the controller receives confirmation that each transaction node is operating under the transition mode, instructing the transaction nodes to operate under the second mode.

A method for an online transaction system to transition from operating under a first mode where transaction nodes identify consecutive transactions with timestamps based on global clock servers (GCSs) coupled to the transaction nodes, to operating under a second mode where the transactions nodes identify sequential transactions with sequential identification numbers obtained from a global transaction server (GTS), the method comprising:

• at a transaction node of the transaction nodes:
• receiving a command to operate under a transition mode;
• when in the transition mode,
• obtaining, for a transaction conducted at the transaction node, a timestamp (ts) and a timestamp error bound (eb), the ts and the eb being based on the GCSs;
• providing ts and eb to the GTS operating under the transition mode;
• receiving from the GTS a modified timestamp (ts_reply) and a modified error bound (eb′);
• and
• timestamping the transaction with ts_reply.

A method for an online transaction system to transition from operating under a first mode where transactions nodes identify sequential transactions with sequential identification numbers obtained from a global transaction server (GTS) to a second mode where the transaction nodes identify consecutive transactions with timestamps based on a global clock servers (GCSs) coupled to the transaction nodes, the method comprising:

• at the GTS:
• receiving a command to switch from operating under the first mode to operating under a transition mode;
• when the GTS is operating under the transition mode:
• for a transaction initiated after the GTS switched to operating under the transition mode:
• receiving a transaction timestamp (ts) and an error bound (eb) of the timestamp from a particular transaction node, the ts and the eb being based on the GCSs, the GTS having associated thereto:
• an identification number of a last transaction conducted by the GTS,
• timestamps previously received (previous_tss) at the GTS, and
• error bounds of the timestamps previously received (previous_ebs) at the GTS;
• obtaining a modified timestamp (ts_reply) by determining a maximum value between the ts, the previous_tss, and the identification number of the last transaction incremented by a pre-determined increment value;
• determining a modified error bound (eb′) by adding the eb to a difference between ts_reply and ts;
• and
• providing the ts_reply and the eb′ to the particular transaction node to cause the transaction node to timestamp the transaction with ts_reply, and to wait for a duration of eb′ before requesting any further timestamp.