Automatic prevention of plan regressions

A method comprising:

• in a first user database session, in response to receiving a first database statement:
• generating a first execution plan,
• while executing the first execution plan, recording first performance data that indicates one or more first performance metrics of executing the first execution plan for the first database statement;
• after recording the first performance data, receiving a second database statement, wherein the first execution plan can be used to generate a result for the second database statement;
• in a second user database session, in response to receiving the second database statement:
• generating a second execution plan,
• while executing the second execution plan, recording second performance data that indicates one or more second performance metrics of executing the second execution plan for the second database statement;
• performing a comparison between the first performance data and the second performance data;
• based on the comparison, determining whether to store the second execution plan for future use when processing the second database statement or another database statement for which the second execution plan can be used;
• in response to receiving the second database statement:
• determining a statement identifier for the second database statement;
• based on the statement identifier, identifying a particular bit in a first bit vector;
• determining whether the particular bit is set;
• in response to determining that the particular bit is set, determining whether the second execution plan matches the first execution plan;
• wherein the method is performed by one or more computing devices.

One or more non-transitory storage media storing instructions which, when executed by one or more computing devices, cause:

• in a first user database session, in response to receiving a first database statement:
• generating a first execution plan,
• while executing the first execution plan, recording first performance data that indicates one or more first performance metrics of executing the first execution plan for the first database statement;
• wherein the one or more first performance metrics pertain to one or more of Central Processing Unit time, elapsed time, buffer gets, disk reads, or temporary space usage;
• after recording the first performance data, receiving a second database statement, wherein the first execution plan can be used to generate a result for the second database statement;
• in a second user database session, in response to receiving the second database statement:
• generating a second execution plan,
• while executing the second execution plan, recording second performance data that indicates one or more second performance metrics of executing the second execution plan for the second database statement;
• performing a comparison between the first performance data and the second performance data;
• based on the comparison, determining whether to store the second execution plan for future use when processing the second database statement or another database statement for which the second execution plan can be used.