Patent Publication Number: US-10776374-B2

Title: Self-monitoring time series database system based on monitored rate of change

Description:
COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND 
     The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. 
     Time series data is a sequence of data points, typically consisting of successive measurements made over a time interval. Examples of time series data are ocean tides, counts of sunspots, and the daily closing value of the Dow Jones Industrial Average. Time series data is frequently plotted via line charts. Many domains of applied science and engineering that involve temporal measurements use time series data. Time series data analysis includes methods for analyzing time series data in order to extract meaningful statistics and other characteristics of the data. Time series data forecasting is the use of a model to predict future values based on previously observed values. A time series database is a computer system that is optimized for handling time series data. In some fields, time series data is called a profile, a curve, or a trace. Despite the disparate names, many of the same mathematical operations, queries, or database transactions are useful for analyzing each of these time series data types. The implementation of a computerized database system that can correctly, reliably, and efficiently implement these operations must be specialized for time series data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following drawings like reference numbers are used to refer to like elements. Although the following figures depict various examples, the one or more implementations are not limited to the examples depicted in the figures. 
         FIG. 1A  and  FIG. 1B  depict an operational flow diagram illustrating a high level overview of a method for a self-monitoring time series database system based on monitored rate of change, in an embodiment; 
         FIG. 2  illustrates a block diagram of an example of an environment wherein an on-demand database service might be used; and 
         FIG. 3  illustrates a block diagram of an embodiment of elements of  FIG. 2  and various possible interconnections between these elements. 
     
    
    
     DETAILED DESCRIPTION 
     General Overview 
     Systems and methods are provided for a self-monitoring time series database system based on monitored rate of change. As used herein, the term multi-tenant database system refers to those systems in which various elements of hardware and software of the database system may be shared by one or more customers. For example, a given application server may simultaneously process requests for a great number of customers, and a given database table may store rows for a potentially much greater number of customers. As used herein, the term query plan refers to a set of steps used to access information in a database system. Next, methods and mechanisms for a self-monitoring time series database system based on monitored rate of change will be described with reference to example embodiments. The following detailed description will first describe a method for a self-monitoring time series database system based on monitored rate of change. 
     In accordance with embodiments described herein, there are provided methods and systems for a self-monitoring time series database system based on monitored rate of change. One skilled in the art will understand that a time series database system is a computer system that is optimized for handling time series data, but may be able to handle other data as well. A time series database system receives an alert trigger condition associated with multiple time series data points corresponding to multiple subsystems of the time series database system. The time series database system aggregates the multiple time series data points associated with a first time into a first internal time series data point that is internal to the time series database system. The time series database system aggregates the multiple time series data points associated with a second time into a second internal time series data point that is internal to the time series database system if the first internal time series data point does not meet the alert trigger condition. The time series database system calculates a projected internal time series data point based on the first internal time series data point and the second internal time series data point if the second internal time series data point does not meet the alert trigger condition. The time series database system outputs a projected alert notification associated with the projected internal time series data point and the alert trigger condition if the projected internal time series data point meets the alert trigger condition. 
     For example, a system administrator for a time series database system submits an alert trigger condition of 1,500 web service API calls per minute for the time series database system, and the time series database system identifies 5 time series data points that indicate web service API calls for 5 subsystems of the time series database system. The time series database system aggregates the 5 time series data points, which indicate a total of 1,200 web service API calls for the 5 subsystems at 11:02 A.M., into a first internal time series data point in the time series database system. The first internal time series data point indicating 1,200 web service API calls at 11:02 A.M. does not meet the alert trigger condition of 1,500 web service API calls per minute. Therefore, the time series database system aggregates the 5 time series data points, which indicate a total of 1,300 web service API calls for the 5 subsystems at 11:03 A.M., into a second internal time series data point. 
     Furthermore, the second internal time series data point indicating 1,300 web service API calls at 11:03 A.M. does not meet the alert trigger condition of 1,500 web service API calls per minute. Therefore, the time series database system calculates a projected internal time series data point of 1,500 web service API calls per minute at 11:05 A.M. based on 1,200 web service API calls per minute at 11:02 A.M. and 1,300 web service API calls per minute at 11:03 A.M. The time series database system outputs an alert email to inform a system administrator that the web service API calls for the 5 subsystems is projected to meet the alert trigger condition of 1,500 web service API calls per minute at 11:05 A.M. In contrast to other monitoring systems that monitor the health and state of time series database systems based on data that reflects a single point in time, the self-monitoring time series database system of the present disclosure monitors the health and state of time series database systems based on projecting time series data that reflects multiple points in time. 
     While one or more implementations and techniques are described with reference to an embodiment in which a self-monitoring time series database system based on monitoring rate of change is implemented in a system having an application server providing a front end for an on-demand database service capable of supporting multiple tenants, the one or more implementations and techniques are not limited to multi-tenant databases nor deployment on application servers. Embodiments may be practiced using other database architectures, i.e., ORACLE®, DB2® by IBM and the like without departing from the scope of the embodiments claimed. 
     Any of the embodiments described herein may be used alone or together with one another in any combination. The one or more implementations encompassed within this specification may also include embodiments that are only partially mentioned or alluded to or are not mentioned or alluded to at all in this brief summary or in the abstract. Although various embodiments may have been motivated by various deficiencies with the prior art, which may be discussed or alluded to in one or more places in the specification, the embodiments do not necessarily address any of these deficiencies. In other words, different embodiments may address different deficiencies that may be discussed in the specification. Some embodiments may only partially address some deficiencies or just one deficiency that may be discussed in the specification, and some embodiments may not address any of these deficiencies. 
       FIG. 1A  and  FIG. 1B  depict an operational flow diagram illustrating a high level overview of a method  100  for a self-monitoring time series database system based on monitoring rate of change. A time series database system receives an alert trigger condition associated with multiple time series data points corresponding to multiple subsystems of the time series database system, block  102 . For example and without limitation, this can include a system administrator for a time series database system submitting an alert trigger condition of 1,500 web service API calls per minute for the time series database system. This may also include the time series database system identifying 5 time series data points that indicate web service API calls for 5 subsystems of the time series database system. 
     Although this example describes the time series database system identifying the multiple time series data points that are associated with the alert trigger condition, a system administrator may identify the multiple time series data points that are associated with the alert trigger condition when submitting the alert trigger condition. While this example describes the time series database system receiving and processing a single alert trigger condition associated with multiple time series data points corresponding to multiple subsystems of the time series database system, the time series database system may receive and process any number of alert trigger conditions. Even though this example describes the time series database system receiving an alert trigger condition from a system administrator, the time series database may also receive an alert trigger condition from a configuration file. 
     For example, upon startup, the time series database system initially receives an alert trigger condition of 2,000 web service API calls per minute from a configuration file that was pre-configured prior to startup of the time series database system. Continuing this example, after months of operation, the time series database system receives an alert trigger condition of 1,500 web service API calls per minute from a system administrator who decided that the alert trigger condition of 2,000 web service API calls per minute was set too high for responding to the corresponding alert notification in a timely manner. 
     After receiving the alert trigger condition associated with multiple time series data points, the time series database system aggregates the multiple time series data points associated with a first time into a first internal time series data point that is internal to the time series database system, block  104 . By way of example and without limitation, this can include the time series database system: 1) creating a global counter, 2) aggregating the 5 time series data points that indicate 1,200 web service API calls for the 5 subsystems at 11:02 A.M., into the global counter, 3) disabling subsystem aggregation to the global counter, 4) copying the aggregated value of 1,200 in the global counter to a temporary data structure, 5) resetting the global counter to zero, enabling subsystem aggregation to the global counter, and 6) persisting the aggregated value of 1,200 in the temporary data structure into a first internal time series data point in the time series database system. 
     Although this example describes the time series database system aggregating a single internal time series data point from multiple corresponding time series data points, the time series database system may aggregate any number of internal time series data points from their multiple corresponding time series data points. While this example describes the time series database system copying the aggregated value in the global counter to a temporary data structure, and then persisting the aggregated value in the temporary data structure to an internal time series data point, the time series database system may also copy the aggregated value in the global counter to an internal time series data point. 
     After aggregating the multiple time series data points associated with the first time into the first internal time series data point, the time series database system evaluates whether the first internal time series data point meets the alert trigger condition, block  106 . In embodiments, this can include the time series database system evaluating whether the first internal time series data point aggregating the 5 time series data points that indicate a total of 1,200 web service API calls for the 5 subsystems at 11:02 A.M. meets the alert trigger condition of 1,500 web service API calls per minute for the time series database system. Although this example describes an alert trigger condition based on an internal time series data point meeting an alert threshold only once, the alert trigger condition may be met when an internal time series data point meets an alert threshold for any time period, such as 5 consecutive minutes, or when an internal time series data point meets an alert threshold any number of times in any time period, such as by meeting an alert threshold at least 7 times in any time period of 13 consecutive minutes. Even though this example describes the time series database system evaluating an internal time series data point on a minute-to-minute basis, the periodic evaluation period may be of any time duration, such as seconds or hours. While this example describes the time series database system evaluating whether a single internal time series data point meets a single alert trigger condition, the time series database system may evaluate any number of internal time series data points, and the time series database system may evaluate whether each one of these internal time series data points meets any number of alert trigger conditions. 
     The time series database system may evaluate that an internal time series data point meets an alert trigger condition if no data is collected from at least one of the multiple time series data points. For example, the time series database system evaluates that the alert trigger condition of 1,500 web service API calls per minute for the time series database system is met because no data is collected from a time series data point that indicates web service API calls for one of the subsystems. This lack of data collected may also indicate that the subsystem is so overwhelmed with web service API calls that the subsystem cannot record the number of its own web service API calls. 
     If the first internal time series data point meets the alert trigger condition, the method  100  continues to block  108  to output an alert notification. If the first internal time series data point does not meet the alert trigger condition, the method  100  proceeds to block  110  to aggregate the multiple time series data points for the multiple subsystems into a second internal time series data point. 
     If the first internal time series data point meets the alert trigger condition, the time series database system outputs an alert notification associated with the first internal time series data point and the alert trigger condition, block  108 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator that the first internal time series data point indicates that the web service API calls for the 5 subsystems exceeds 1,500 web service API calls per minute for the time series database system, but does not repeat a similar alert email to the system administrator until 5 minutes later even if the web service API calls for the 5 subsystems continue to exceed 1,500 web service API calls per minute for the time series database system. 
     Waiting any specific amount of time to send additional alert notifications is referred to as a cool down period, which enables a system administrator to take action on a previous alert notification without bombarding the system administrator with a seemingly endless supply of alert notifications while the corresponding time series data points continue to meet the corresponding alert trigger condition. Although this example describes the time series database system communicating an alert notification via an email, the time series database system may communicate an alert notification via any combination of communications including emails, text messages, display screen updates, audible alarms, social network posts, tweets, writes to database records, etc. The system may also communicate an alert notification to a computer system, even the time series database system itself, in the form of control feedback, such that the computer system receiving the alert notification can take an action to mitigate an imminent failure. 
     If the first internal time series data point does not meet the alert trigger condition, the time series database system aggregates the multiple time series data points associated with a second time into a second internal time series data point that is internal to the time series database system, block  110 . By way of example and without limitation, this can include the time series database system aggregating the 5 time series data points for the 5 subsystems, which indicate a total of 1,300 web service API calls for the 5 subsystems at 11:03 A.M., into a second internal time series data point. The time series database system may aggregate the second internal time series data point similarly to how the time series database system aggregated the first internal time series data point, as described above. 
     After aggregating the multiple time series data points associated with the second time into the second internal time series data point, the time series database system evaluates whether the second internal time series data point meets the alert trigger condition, block  112 . In embodiments, this can include the time series database system evaluating whether the second internal time series data point indicating 1,300 web service API calls for the 5 subsystems at 11:03 A.M. meets the alert trigger condition of 1,500 web service API calls per minute. If the second internal time series data point meets the alert trigger condition, the method  100  continues to block  114  to output an alert notification. If the second internal time series data point does not meet the alert trigger condition, the method  100  proceeds to block  116  to calculate a projected internal time series data point based on the first internal time series data point and the second internal time series data point. 
     If the second internal time series data point meets the alert trigger condition, the time series database system outputs an alert notification associated with the second internal time series data point and the alert trigger condition, block  114 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator that the second internal time series data point indicates that the web service API calls for the 5 subsystems exceeds 1,500 web service API calls per minute for the time series database system. 
     If the second internal time series data point does not meet the alert trigger condition, the time series database system calculates a projected internal time series data point based on the first internal time series data point and the second internal time series data point block  116 . By way of example and without limitation, this can include the time series database system calculating a projected internal time series data point of 1,500 web service API calls per minute at 11:05 A.M. based on 1,200 web service API calls per minute at 11:02 A.M. and 1,300 web service API calls per minute at 11:03 A.M. 
     Calculating the projected internal time series data point may be based on the first internal time series data point and/or the second internal time series data point meeting a data threshold. For example, since the first internal time series data point&#39;s value of 1,200 web service API calls per minute and the second internal time series data point&#39;s value of 1,300 web service API calls per minute are both above the 50% threshold of the alert trigger condition of 1,500 web service API calls per minute, the time series database system calculates the projected internal time series data point. In another example, if the first internal time series data point&#39;s value of 600 web service API calls per minute and the second internal time series data point&#39;s value of 650 web service API calls per minute are both below the 50% threshold of the alert trigger condition of 1,500 web service API calls per minute, the time series database system does not calculate the projected internal time series data point, thereby avoiding unnecessary calculations. 
     Although this example describes the time series database system calculating the projected internal time series data point based on only two internal time series data points, the time series database system may calculate the projected internal time series data point based on any number of internal time series data points. While this example describes the time series database system calculating the projected internal time series data point based on a liner projection, the time series database system may calculate the projected internal time series data point based on any type of projection, such as exponential, logarithmic, or regression analysis, or combination thereof. Even though this example describes the time series database system calculating the projected internal time series data point based on meeting the alert trigger condition, the time series database system may calculate the projected internal time series data point based on a specified amount of time into the future, and then evaluate whether the projected internal time series data point meets the alert trigger condition within a specified time threshold. 
     After calculating the projected internal time series data point, the time series database system evaluates whether the projected internal time series data point meets the alert trigger condition, block  118 . In embodiments, this can include the time series database system evaluating whether the projected internal time series data point of 1,500 web service API calls per minute at 11:05 A.M. meets the alert trigger condition of 1,500 web service API calls per minute. Evaluating whether the projected internal time series data point meets the alert trigger condition may be based on meeting a time threshold. For example, if the projected internal time series data point is projected to meet the alert trigger condition in 5 minutes, the time series database system processes the projected internal time series data point as having met the alert trigger condition. In another example, if the projected internal time series data point is projected to meet the alert trigger condition in 5 months, the time series database system processes the projected internal time series data point as having not met the alert trigger condition. 
     If the projected internal time series data point meets the alert trigger condition, the method  100  continues to block  120  to output a projected alert notification. If the projected internal time series data point does not meet the alert trigger condition, the method  100  proceeds to block  122  to optionally aggregate time series data points for time series database systems into a distributed network time series data point. 
     If the projected internal time series data point meets the alert trigger condition, the time series database system outputs a projected alert notification associated with the projected internal time series data point and the alert trigger condition, block  120 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator that the web service API calls for the 5 subsystems is projected to be 1,500 web service API calls per minute at 11:05 A.M. Although this example describes the time series database system communicating a projected alert notification via an email, the time series database system may communicate a projected alert notification via any combination of communications including emails, text messages, display screen updates, audible alarms, social network posts, tweets, writes to database records, etc. The system may also communicate an alert notification to a computer system, even the time series database system itself, in the form of control feedback, such that the computer system receiving the alert notification can take an action to mitigate an imminent failure. In contrast to other monitoring systems that monitor the health and state of time series database systems based on data that reflects a single point in time, the self-monitoring time series database system of the present disclosure monitors the health and state of time series database systems based on projecting time series data that reflects multiple points in time. 
     When the time series database system has no more internal time series data points to evaluate against their corresponding alert trigger conditions, the time series database system optionally aggregates the first internal time series data point corresponding to the time series database system with another first time series data point corresponding to another time series database system into a first distributed network time series data point, block  122 . By way of example and without limitation, this can include the time series database system aggregating the first internal time series data point indicating 1,200 web service API calls for the 5 subsystems at 11:02 A.M. with another first time series data point indicating 2,000 web service API calls for another time series database system&#39;s 4 subsystems at 11:02 A.M. into a first distributed network time series data point indicating 3,200 web service API calls at 11:02 A.M. for the distributed network. 
     After aggregating the first time series data points for the time series database systems into the first distributed network time series data point, the time series database system optionally evaluates whether the first distributed network time series data point meets a corresponding alert trigger condition, block  124 . In embodiments, this can include the time series database system evaluating whether the first distributed network time series data point indicating 3,200 web service API calls for the distributed network at 11:02 A.M. meets a corresponding alert trigger condition of 3,500 web service API calls per minute. The alert trigger condition for the distributed network time series data point may be provided by a system administrator or a configuration file, or may be a combination of the alert trigger conditions for each of the time series database system&#39;s corresponding time series data points. Even though this example describes the time series database system evaluating a distributed network time series data point that is based on data communicated from an external time series database system, the two time series database systems can continue to self-monitor their own health and state even if the external communication between the two time series database systems is disrupted. 
     If the first distributed network time series data point meets the corresponding alert trigger condition, the method  100  continues to block  126  to output an alert notification. If the first distributed network time series data point does not meet the corresponding alert trigger condition, the method  100  proceeds to block  128  to aggregate the second time series data points for the time series database systems into a second distributed network time series data point. 
     If the first distributed network time series data point meets the corresponding alert trigger condition, the time series database system optionally outputs an alert notification associated with the first distributed network time series data point and the corresponding alert trigger condition, block  126 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator for the time series database system that the first distributed network time series data point indicates that web service API calls for the distributed network exceeds 3,500 web service API calls per minute at 11:02 A.M. 
     If the first distributed network time series data point does not meet the corresponding alert trigger condition, the time series database system optionally aggregates the second internal time series data point for the time series database system with a second time series data point for the other time series database system into a second distributed network time series data point, block  128 . By way of example and without limitation, this can include the time series database system aggregating the second internal time series data point indicating 1,300 web service API calls for the 5 subsystems at 11:03 A.M. with a second time series data point indicating 2,000 web service API calls for the other time series database system&#39;s 4 subsystems at 11:03 A.M. into a second distributed network time series data point indicating 3,300 web service API calls at 11:03 A.M. for the distributed network. 
     After aggregating the second time series data points for the time series database systems into the second distributed network time series data point, the time series database system optionally evaluates whether the second distributed network time series data point meets a corresponding alert trigger condition, block  130 . In embodiments, this can include the time series database system evaluating whether the second distributed network time series data point indicating 3,300 web service API calls for the distributed network at 11:03 A.M. meets a corresponding alert trigger condition of 3,500 web service API calls per minute. If the second distributed network time series data point meets the corresponding alert trigger condition, the method  100  continues to block  132  to output an alert notification. If the second distributed network time series data point does not meet the corresponding alert trigger condition, the method  100  proceeds to block  134  to calculate a projected distributed network time series data point based on the first distributed network time series data point and the second distributed network time series data point. 
     If the second distributed network time series data point meets the corresponding alert trigger condition, the time series database system optionally outputs an alert notification associated with the second distributed network time series data point and the corresponding alert trigger condition, block  132 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator for the time series database system that the second distributed network time series data point indicates that web service API calls for the distributed network exceeds 3,500 web service API calls per minute at 11:03 A.M. 
     If the second distributed network time series data point does not meet the corresponding alert trigger condition, the time series database system optionally calculates a projected distributed network time series data point based on the first distributed network time series data point and the second distributed network time series data point block  134 . By way of example and without limitation, this can include the time series database system calculating a projected internal time series data point of 3,500 web service API calls per minute at 11:05 A.M. based on 3,200 web service API calls per minute at 11:02 A.M. and 3,300 web service API calls per minute at 11:03 A.M. 
     Calculating the projected distributed network time series data point may be based on the first distributed network time series data point and/or the second distributed network time series data point meeting a data threshold. For example, since the first distributed network time series data point&#39;s value of 3,200 web service API calls per minute and the second distributed network time series data point&#39;s value of 3,300 web service API calls per minute are both above the 50% threshold of the corresponding alert trigger condition of 3,500 web service API calls per minute, the time series database system calculates the projected distributed network time series data point. In another example, if the first distributed network time series data point&#39;s value of 1,600 web service API calls per minute and the second distributed network time series data point&#39;s value of 1,650 web service API calls per minute are both below the 50% threshold of the corresponding alert trigger condition of 3,500 web service API calls per minute, the time series database system does not calculate the projected distributed network time series data point, thereby avoiding unnecessary calculations. 
     Although this example describes the time series database system calculating the projected distributed network time series data point based on only two distributed network time series data points, the time series database system may calculate the projected distributed network time series data point based on any number of distributed network time series data points. While this example describes the time series database system calculating the projected distributed network time series data point based on a liner projection, the time series database system may calculate the projected distributed network time series data point based on any type of projection, such as exponential, logarithmic, or regression analysis, or combination thereof. Even though this example describes the time series database system calculating the projected distributed network time series data point based on meeting the corresponding alert trigger condition, the time series database system may calculate the projected distributed network time series data point based on a specified amount of time into the future, and then evaluate whether the projected distributed network time series data point meets the corresponding alert trigger condition within a specified time threshold. 
     After calculating the projected distributed network time series data point, the time series database system optionally evaluates whether the projected distributed network time series data point meets the corresponding alert trigger condition, block  136 . In embodiments, this can include the time series database system evaluating whether the projected distributed network time series data point of 3,500 web service API calls per minute at 11:05 A.M. meets the corresponding alert trigger condition of 3,500 web service API calls per minute. Evaluating whether the projected distributed network time series data point meets the corresponding alert trigger condition may be based on meeting a time threshold. For example, if the projected distributed network time series data point is projected to meet the corresponding alert trigger condition in 5 minutes, the time series database system processes the projected distributed network time series data point as having met the alert trigger condition. In another example, if the projected distributed network time series data point is projected to meet the corresponding alert trigger condition in 5 months, the time series database system processes the projected distributed network time series data point as having not met the corresponding alert trigger condition. 
     If the projected distributed network time series data point meets the corresponding alert trigger condition, the method  100  continues to block  138  to output a projected alert notification. If the projected distributed network time series data point does not meet the corresponding alert trigger condition, the method  100  terminates. 
     If the projected distributed network time series data point meets the corresponding alert trigger condition, the time series database system optionally outputs a projected alert notification associated with the projected distributed network time series data point and the corresponding alert trigger condition, block  138 . For example and without limitation, this can include the time series database system outputting an alert email to inform a system administrator that the web service API calls for the distributed network is projected to be 3,500 web service API calls per minute at 11:05 A.M. 
     The method  100  may be repeated as desired. Although this disclosure describes the blocks  102 - 138  executing in a particular order, the blocks  102 - 138  may be executed in a different order. In other implementations, each of the blocks  102 - 138  may also be executed in combination with other blocks and/or some blocks may be divided into a different set of blocks. 
     System Overview 
       FIG. 2  illustrates a block diagram of an environment  210  wherein an on-demand database service might be used. The environment  210  may include user systems  212 , a network  214 , a system  216 , a processor system  217 , an application platform  218 , a network interface  220 , a tenant data storage  222 , a system data storage  224 , program code  226 , and a process space  228 . In other embodiments, the environment  210  may not have all of the components listed and/or may have other elements instead of, or in addition to, those listed above. 
     The environment  210  is an environment in which an on-demand database service exists. A user system  212  may be any machine or system that is used by a user to access a database user system. For example, any of the user systems  212  may be a handheld computing device, a mobile phone, a laptop computer, a work station, and/or a network of computing devices. As illustrated in  FIG. 2  (and in more detail in  FIG. 3 ) the user systems  212  might interact via the network  214  with an on-demand database service, which is the system  216 . 
     An on-demand database service, such as the system  216 , is a database system that is made available to outside users that do not need to necessarily be concerned with building and/or maintaining the database system, but instead may be available for their use when the users need the database system (e.g., on the demand of the users). Some on-demand database services may store information from one or more tenants stored into tables of a common database image to form a multi-tenant database system (MTS). Accordingly, the “on-demand database service  216 ” and the “system  216 ” will be used interchangeably herein. A database image may include one or more database objects. A relational database management system (RDMS) or the equivalent may execute storage and retrieval of information against the database object(s). The application platform  218  may be a framework that allows the applications of the system  216  to run, such as the hardware and/or software, e.g., the operating system. In an embodiment, the on-demand database service  216  may include the application platform  218  which enables creation, managing and executing one or more applications developed by the provider of the on-demand database service, users accessing the on-demand database service via user systems  212 , or third party application developers accessing the on-demand database service via the user systems  212 . 
     The users of the user systems  212  may differ in their respective capacities, and the capacity of a particular user system  212  might be entirely determined by permissions (permission levels) for the current user. For example, where a salesperson is using a particular user system  212  to interact with the system  216 , that user system  212  has the capacities allotted to that salesperson. However, while an administrator is using that user system  212  to interact with the system  216 , that user system  212  has the capacities allotted to that administrator. In systems with a hierarchical role model, users at one permission level may have access to applications, data, and database information accessible by a lower permission level user, but may not have access to certain applications, database information, and data accessible by a user at a higher permission level. Thus, different users will have different capabilities with regard to accessing and modifying application and database information, depending on a user&#39;s security or permission level. 
     The network  214  is any network or combination of networks of devices that communicate with one another. For example, the network  214  may be any one or any combination of a LAN (local area network), WAN (wide area network), telephone network, wireless network, point-to-point network, star network, token ring network, hub network, or other appropriate configuration. As the most common type of computer network in current use is a TCP/IP (Transfer Control Protocol and Internet Protocol) network, such as the global internetwork of networks often referred to as the “Internet” with a capital “I,” that network will be used in many of the examples herein. However, it should be understood that the networks that the one or more implementations might use are not so limited, although TCP/IP is a frequently implemented protocol. 
     The user systems  212  might communicate with the system  216  using TCP/IP and, at a higher network level, use other common Internet protocols to communicate, such as HTTP, FTP, AFS, WAP, etc. In an example where HTTP is used, the user systems  212  might include an HTTP client commonly referred to as a “browser” for sending and receiving HTTP messages to and from an HTTP server at the system  216 . Such an HTTP server might be implemented as the sole network interface between the system  216  and the network  214 , but other techniques might be used as well or instead. In some implementations, the interface between the system  216  and the network  214  includes load sharing functionality, such as round-robin HTTP request distributors to balance loads and distribute incoming HTTP requests evenly over a plurality of servers. At least as for the users that are accessing that server, each of the plurality of servers has access to the MTS&#39; data; however, other alternative configurations may be used instead. 
     In one embodiment, the system  216 , shown in  FIG. 2 , implements a web-based customer relationship management (CRM) system. For example, in one embodiment, the system  216  includes application servers configured to implement and execute CRM software applications as well as provide related data, code, forms, webpages and other information to and from the user systems  212  and to store to, and retrieve from, a database system related data, objects, and Webpage content. With a multi-tenant system, data for multiple tenants may be stored in the same physical database object, however, tenant data typically is arranged so that data of one tenant is kept logically separate from that of other tenants so that one tenant does not have access to another tenant&#39;s data, unless such data is expressly shared. In certain embodiments, the system  216  implements applications other than, or in addition to, a CRM application. For example, the system  216  may provide tenant access to multiple hosted (standard and custom) applications, including a CRM application. User (or third party developer) applications, which may or may not include CRM, may be supported by the application platform  218 , which manages creation, storage of the applications into one or more database objects and executing of the applications in a virtual machine in the process space of the system  216 . 
     One arrangement for elements of the system  216  is shown in  FIG. 2 , including the network interface  220 , the application platform  218 , the tenant data storage  222  for tenant data  223 , the system data storage  224  for system data  225  accessible to the system  216  and possibly multiple tenants, the program code  226  for implementing various functions of the system  216 , and the process space  228  for executing MTS system processes and tenant-specific processes, such as running applications as part of an application hosting service. Additional processes that may execute on the system  216  include database indexing processes. 
     Several elements in the system shown in  FIG. 2  include conventional, well-known elements that are explained only briefly here. For example, each of the user systems  212  could include a desktop personal computer, workstation, laptop, PDA, cell phone, or any wireless access protocol (WAP) enabled device or any other computing device capable of interfacing directly or indirectly to the Internet or other network connection. Each of the user systems  212  typically runs an HTTP client, e.g., a browsing program, such as Microsoft&#39;s Internet Explorer browser, Netscape&#39;s Navigator browser, Opera&#39;s browser, or a WAP-enabled browser in the case of a cell phone, PDA or other wireless device, or the like, allowing a user (e.g., subscriber of the multi-tenant database system) of the user systems  212  to access, process and view information, pages and applications available to it from the system  216  over the network  214 . Each of the user systems  212  also typically includes one or more user interface devices, such as a keyboard, a mouse, trackball, touch pad, touch screen, pen or the like, for interacting with a graphical user interface (GUI) provided by the browser on a display (e.g., a monitor screen, LCD display, etc.) in conjunction with pages, forms, applications and other information provided by the system  216  or other systems or servers. For example, the user interface device may be used to access data and applications hosted by the system  216 , and to perform searches on stored data, and otherwise allow a user to interact with various GUI pages that may be presented to a user. As discussed above, embodiments are suitable for use with the Internet, which refers to a specific global internetwork of networks. However, it should be understood that other networks can be used instead of the Internet, such as an intranet, an extranet, a virtual private network (VPN), a non-TCP/IP based network, any LAN or WAN or the like. 
     According to one embodiment, each of the user systems  212  and all of its components are operator configurable using applications, such as a browser, including computer code run using a central processing unit such as an Intel Pentium® processor or the like. Similarly, the system  216  (and additional instances of an MTS, where more than one is present) and all of their components might be operator configurable using application(s) including computer code to run using a central processing unit such as the processor system  217 , which may include an Intel Pentium® processor or the like, and/or multiple processor units. A computer program product embodiment includes a machine-readable storage medium (media) having instructions stored thereon/in which can be used to program a computer to perform any of the processes of the embodiments described herein. Computer code for operating and configuring the system  216  to intercommunicate and to process webpages, applications and other data and media content as described herein are preferably downloaded and stored on a hard disk, but the entire program code, or portions thereof, may also be stored in any other volatile or non-volatile memory medium or device as is well known, such as a ROM or RAM, or provided on any media capable of storing program code, such as any type of rotating media including floppy disks, optical discs, digital versatile disk (DVD), compact disk (CD), microdrive, and magneto-optical disks, and magnetic or optical cards, nanosystems (including molecular memory ICs), or any type of media or device suitable for storing instructions and/or data. Additionally, the entire program code, or portions thereof, may be transmitted and downloaded from a software source over a transmission medium, e.g., over the Internet, or from another server, as is well known, or transmitted over any other conventional network connection as is well known (e.g., extranet, VPN, LAN, etc.) using any communication medium and protocols (e.g., TCP/IP, HTTP, HTTPS, Ethernet, etc.) as are well known. It will also be appreciated that computer code for implementing embodiments can be implemented in any programming language that can be executed on a client system and/or server or server system such as, for example, C, C++, HTML, any other markup language, Java™, JavaScript, ActiveX, any other scripting language, such as VBScript, and many other programming languages as are well known may be used. (Java™ is a trademark of Sun Microsystems, Inc.). 
     According to one embodiment, the system  216  is configured to provide webpages, forms, applications, data and media content to the user (client) systems  212  to support the access by the user systems  212  as tenants of the system  216 . As such, the system  216  provides security mechanisms to keep each tenant&#39;s data separate unless the data is shared. If more than one MTS is used, they may be located in close proximity to one another (e.g., in a server farm located in a single building or campus), or they may be distributed at locations remote from one another (e.g., one or more servers located in city A and one or more servers located in city B). As used herein, each MTS could include one or more logically and/or physically connected servers distributed locally or across one or more geographic locations. Additionally, the term “server” is meant to include a computer system, including processing hardware and process space(s), and an associated storage system and database application (e.g., OODBMS or RDBMS) as is well known in the art. It should also be understood that “server system” and “server” are often used interchangeably herein. Similarly, the database object described herein can be implemented as single databases, a distributed database, a collection of distributed databases, a database with redundant online or offline backups or other redundancies, etc., and might include a distributed database or storage network and associated processing intelligence. 
       FIG. 3  also illustrates the environment  210 . However, in  FIG. 3  elements of the system  216  and various interconnections in an embodiment are further illustrated.  FIG. 3  shows that the each of the user systems  212  may include a processor system  212 A, a memory system  212 B, an input system  212 C, and an output system  212 D.  FIG. 3  shows the network  214  and the system  216 .  FIG. 3  also shows that the system  216  may include the tenant data storage  222 , the tenant data  223 , the system data storage  224 , the system data  225 , a User Interface (UI)  330 , an Application Program Interface (API)  332 , a PL/SOQL  334 , save routines  336 , an application setup mechanism  338 , applications servers  300   1 - 300   N , a system process space  302 , tenant process spaces  304 , a tenant management process space  310 , a tenant storage area  312 , a user storage  314 , and application metadata  316 . In other embodiments, the environment  210  may not have the same elements as those listed above and/or may have other elements instead of, or in addition to, those listed above. 
     The user systems  212 , the network  214 , the system  216 , the tenant data storage  222 , and the system data storage  224  were discussed above in reference to  FIG. 2 . Regarding the user systems  212 , the processor system  212 A may be any combination of one or more processors. The memory system  212 B may be any combination of one or more memory devices, short term, and/or long term memory. The input system  212 C may be any combination of input devices, such as one or more keyboards, mice, trackballs, scanners, cameras, and/or interfaces to networks. The output system  212 D may be any combination of output devices, such as one or more monitors, printers, and/or interfaces to networks. As shown by  FIG. 3 , the system  216  may include the network interface  220  (of  FIG. 2 ) implemented as a set of HTTP application servers  300 , the application platform  218 , the tenant data storage  222 , and the system data storage  224 . Also shown is the system process space  302 , including individual tenant process spaces  304  and the tenant management process space  310 . Each application server  300  may be configured to access tenant data storage  222  and the tenant data  223  therein, and the system data storage  224  and the system data  225  therein to serve requests of the user systems  212 . The tenant data  223  might be divided into individual tenant storage areas  312 , which can be either a physical arrangement and/or a logical arrangement of data. Within each tenant storage area  312 , the user storage  314  and the application metadata  316  might be similarly allocated for each user. For example, a copy of a user&#39;s most recently used (MRU) items might be stored to the user storage  314 . Similarly, a copy of MRU items for an entire organization that is a tenant might be stored to the tenant storage area  312 . The UI  330  provides a user interface and the API  332  provides an application programmer interface to the system  216  resident processes to users and/or developers at the user systems  212 . The tenant data and the system data may be stored in various databases, such as one or more Oracle™ databases. 
     The application platform  218  includes the application setup mechanism  338  that supports application developers&#39; creation and management of applications, which may be saved as metadata into the tenant data storage  222  by the save routines  336  for execution by subscribers as one or more tenant process spaces  304  managed by the tenant management process  310  for example. Invocations to such applications may be coded using the PL/SOQL  334  that provides a programming language style interface extension to the API  332 . A detailed description of some PL/SOQL language embodiments is discussed in commonly owned U.S. Pat. No. 7,730,478 entitled, METHOD AND SYSTEM FOR ALLOWING ACCESS TO DEVELOPED APPLICATIONS VIA A MULTI-TENANT ON-DEMAND DATABASE SERVICE, by Craig Weissman, filed Sep. 21, 2007, which is incorporated in its entirety herein for all purposes. Invocations to applications may be detected by one or more system processes, which manages retrieving the application metadata  316  for the subscriber making the invocation and executing the metadata as an application in a virtual machine. 
     Each application server  300  may be communicably coupled to database systems, e.g., having access to the system data  225  and the tenant data  223 , via a different network connection. For example, one application server  300   1  might be coupled via the network  214  (e.g., the Internet), another application server  300   N-1  might be coupled via a direct network link, and another application server  300   N  might be coupled by yet a different network connection. Transfer Control Protocol and Internet Protocol (TCP/IP) are typical protocols for communicating between application servers  300  and the database system. However, it will be apparent to one skilled in the art that other transport protocols may be used to optimize the system depending on the network interconnect used. 
     In certain embodiments, each application server  300  is configured to handle requests for any user associated with any organization that is a tenant. Because it is desirable to be able to add and remove application servers from the server pool at any time for any reason, there is preferably no server affinity for a user and/or organization to a specific application server  300 . In one embodiment, therefore, an interface system implementing a load balancing function (e.g., an F5 Big-IP load balancer) is communicably coupled between the application servers  300  and the user systems  212  to distribute requests to the application servers  300 . In one embodiment, the load balancer uses a least connections algorithm to route user requests to the application servers  300 . Other examples of load balancing algorithms, such as round robin and observed response time, also can be used. For example, in certain embodiments, three consecutive requests from the same user could hit three different application servers  300 , and three requests from different users could hit the same application server  300 . In this manner, the system  216  is multi-tenant, wherein the system  216  handles storage of, and access to, different objects, data and applications across disparate users and organizations. 
     As an example of storage, one tenant might be a company that employs a sales force where each salesperson uses the system  216  to manage their sales process. Thus, a user might maintain contact data, leads data, customer follow-up data, performance data, goals and progress data, etc., all applicable to that user&#39;s personal sales process (e.g., in the tenant data storage  222 ). In an example of a MTS arrangement, since all of the data and the applications to access, view, modify, report, transmit, calculate, etc., can be maintained and accessed by a user system having nothing more than network access, the user can manage his or her sales efforts and cycles from any of many different user systems. For example, if a salesperson is visiting a customer and the customer has Internet access in their lobby, the salesperson can obtain critical updates as to that customer while waiting for the customer to arrive in the lobby. 
     While each user&#39;s data might be separate from other users&#39; data regardless of the employers of each user, some data might be organization-wide data shared or accessible by a plurality of users or all of the users for a given organization that is a tenant. Thus, there might be some data structures managed by the system  216  that are allocated at the tenant level while other data structures might be managed at the user level. Because an MTS might support multiple tenants including possible competitors, the MTS should have security protocols that keep data, applications, and application use separate. Also, because many tenants may opt for access to an MTS rather than maintain their own system, redundancy, up-time, and backup are additional functions that may be implemented in the MTS. In addition to user-specific data and tenant specific data, the system  216  might also maintain system level data usable by multiple tenants or other data. Such system level data might include industry reports, news, postings, and the like that are sharable among tenants. 
     In certain embodiments, the user systems  212  (which may be client systems) communicate with the application servers  300  to request and update system-level and tenant-level data from the system  216  that may require sending one or more queries to the tenant data storage  222  and/or the system data storage  224 . The system  216  (e.g., an application server  300  in the system  216 ) automatically generates one or more SQL statements (e.g., one or more SQL queries) that are designed to access the desired information. The system data storage  224  may generate query plans to access the requested data from the database. 
     Each database can generally be viewed as a collection of objects, such as a set of logical tables, containing data fitted into predefined categories. A “table” is one representation of a data object, and may be used herein to simplify the conceptual description of objects and custom objects. It should be understood that “table” and “object” may be used interchangeably herein. Each table generally contains one or more data categories logically arranged as columns or fields in a viewable schema. Each row or record of a table contains an instance of data for each category defined by the fields. For example, a CRM database may include a table that describes a customer with fields for basic contact information such as name, address, phone number, fax number, etc. Another table might describe a purchase order, including fields for information such as customer, product, sale price, date, etc. In some multi-tenant database systems, standard entity tables might be provided for use by all tenants. For CRM database applications, such standard entities might include tables for Account, Contact, Lead, and Opportunity data, each containing pre-defined fields. It should be understood that the word “entity” may also be used interchangeably herein with “object” and “table”. 
     In some multi-tenant database systems, tenants may be allowed to create and store custom objects, or they may be allowed to customize standard entities or objects, for example by creating custom fields for standard objects, including custom index fields. U.S. Pat. No. 7,779,039, filed Apr. 2, 2004, entitled “Custom Entities and Fields in a Multi-Tenant Database System”, which is hereby incorporated herein by reference, teaches systems and methods for creating custom objects as well as customizing standard objects in a multi-tenant database system. In certain embodiments, for example, all custom entity data rows are stored in a single multi-tenant physical table, which may contain multiple logical tables per organization. It is transparent to customers that their multiple “tables” are in fact stored in one large table or that their data may be stored in the same table as the data of other customers. 
     While one or more implementations have been described by way of example and in terms of the specific embodiments, it is to be understood that one or more implementations are not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.