Abstract:
Methods and systems are described for shared data sets in an on-line services environment. In one embodiment, a method includes, receiving a request for data stored in a shared database from a user, identifying the requesting user, retrieving the requested data from the shared database, determining whether there are user-specific changes for the retrieved data, changing the retrieved data using the user-specific changes, and supplying the requested data to the user.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/4385559 entitled Shared Data Sets in an On-Line Services Environment, by Sharma, filed Feb. 1, 2011 (Attorney Docket No. 0617PROV), the entire contents of which are incorporated herein by reference. 
     
    
     COPYRIGHT NOTICE 
       [0002]    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. 
       FIELD OF THE INVENTION 
       [0003]    The current invention relates generally to maintaining information in databases and, in particular, to providing shared data sets to multiple customers or users. 
       BACKGROUND 
       [0004]    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. 
         [0005]    In conventional database systems, either on-premise databases or cloud-based databases, maintain information for different customers in separate databases. Even in some multi-tenant database systems, separate instances of a database may be used to store customer data. As a result, when two companies want to work together, typically, a copy of a company&#39;s entire data set has to be provided to the other company. This situation occurs even when the companies are using third party services to host their data. 
         [0006]    Current data marketplaces provide data files for individual consumption by users. These marketplaces are typically independent systems, meaning other data systems import or access data from the marketplace. 
       BRIEF SUMMARY 
       [0007]    In accordance with embodiments, there are provided mechanisms and methods for providing shared data sets for multiple users. These mechanisms and methods for providing shared data sets for multiple users can enable embodiments to provide more reliable and faster 
         [0008]    While the present invention is described with reference to an embodiment in which techniques for providing shared data sets for multiple users are implemented in a system having an application server providing a front end for an on-demand database service capable of supporting multiple tenants, the present invention is not limited to multi-tenant databases nor deployment on application servers. Embodiments may be practiced using other database architectures, i.e., ORACLE®, DB2C® by IBM and the like without departing from the scope of the embodiments claimed. 
         [0009]    Any of the above embodiments may be used alone or together with one another in any combination. Inventions 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 of the invention 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 of the invention do not necessarily address any of these deficiencies. In other words, different embodiments of the invention 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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In the following drawings like reference numbers are used to refer to like elements. Although the following figures depict various examples of the invention, the invention is not limited to the examples depicted in the figures. 
           [0011]      FIG. 1  illustrates a block diagram of an example of an environment wherein shared data sets might be used; and 
           [0012]      FIG. 2  illustrates a block diagram of an embodiment of elements of  FIG. 1  and various possible interconnections between these elements. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    General Overview 
         [0014]    Systems and methods are provided for providing shared data sets for multiple users. These systems and methods are particularly valuable in the context of a multi-tenant database. 
         [0015]    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. 
         [0016]    Relational Shared Data Sets 
         [0017]    To simplify the maintenance of shared data and preserve resources, in one embodiment, a system can provide a common shared data set to multiple customer/users. The common shared data set, in one implementation, is a common database hosting multiple users&#39; information. Basically, multiple data sets are hosted in one single, shared data repository. 
         [0018]    To the end user, this common data set looks no different than a system that employs multiple databases, according to one embodiment. The data displayed and available to the users, in this implementation, includes the information that is meant for them individually. To the end user the functionality of the system is no different than if there were multiple databases. However, at the database system layer, the data sets are stored as a shared single database that multiple users/multiple customers access. 
         [0019]    In one implantation, an end user is able to make changes to data in the database without having those changes propagated to every other user of the database. The end user can make the changes to the database without accessing a different database (e.g., does not need to go to different places to make a change). 
         [0020]    Because multiple people have access to the same data (e.g., in one physical repository), there may be instances when a customer overwrites data or data is changed by a certain user or customer. In one implementation, the database system tracks the changes by maintaining a table that lists the changes. This table may be called a delta table. The delta table may also be maintained in some other format. It could be a list, an object, an array, queue or other data structure. 
         [0021]    To illustrate this idea, assume a shared database includes a data set that lists all of the zip codes and their associated streets in the U.S. This data set is accessed by multiple customers. In one instance, a local customer with access to the data set overwrites a local street name because the people living on the street call the street something different. However, this is a change not every customer wants propagated to the data set. In one implementation, the change is not pushed to the entire data set. It is maintained separately in the delta table. When the local customer accesses the local street name, the shared database system checks to see if there are any associated entries in the delta table. In one embodiment, a flag is set on the record in the shared database indicating that a customer has created a delta table entry for the record. Alternatively, a look-up could be performed each time a record is accessed. Alternatively, metadata associated with a customer includes the delta table and is consulted before performing any look-up. 
         [0022]    In this way, customers can use a data set, make changes, and track the changes. The changes may appear to the customer, but the original, unchanged data set still exists so that changes can be reverted or hidden, if necessary. In addition, the unchanged data set is still available to all other customers. 
         [0023]    In the same or different embodiments, the common shared database may be a multi-tenant database system and shared data set. In one implementation, the data sets are provided and managed by third parties. In such a case, the third parties provide and manage overwrites. 
         [0024]    The system, however, still determines what overwrites apply to which provider and to which consumer. In this way, the most updated and applicable version of data is displayed to the user. 
         [0025]    The system of the present invention is shown in  FIGS. 1 and 2  and includes a delta table. The delta table may be incorporated into the Tenant Data Storage  622  shown in the figures or as a separate shared store. 
         [0026]    Marketplace for Shared Data Sets 
         [0027]    In one implementation, a system, like the one described above or some other one, allows a data set provider (e.g. a provider in the data marketplace) to be able to offer access to data sets in its managed database. The underlying database can be relational, mapped, or implemented in some other way. Customers, through the system, can access the information from multiple data sets. 
         [0028]    To facilitate access to the data sets, the system may have built in relationships that allow users to plug a data set bought in the marketplace into a shared data set or other database. Relationships can be built in and tied to the existing data model. The relationships can be standard and applicable to multiple objects. Moreover, the relationships can be based on standard objects or some set of custom objects. In one implementation, the custom objects are created before relationships between data sets are defined. The built-in relationships allow users to exchange data sets and combine data sets into a shared data set. For example, data bought on the marketplace can be plugged into the shared data set or other database. 
         [0029]    To illustrate, assume a user maintains a list of zip codes. In one implementation, the user could also provide multiple child data sets related to zip codes so a consumer could look up the data set by zip code. For example, the user may provide health care provider information based on zip code data, or census information, or restaurant information, etc. 
         [0030]    In this system, data sets are interrelated. In addition, this system can allow users to resolve inconsistencies in data and version history may also be built into the provided data sets. 
         [0031]    This system can be provided using the same hardware as for the relational shared data sets or using different hardware. The additional purchased data may be stored in the delta table for a particular user. Different users may go into the marketplace and buy additional data that is then stored in that user&#39;s delta table. 
         [0032]    Common Objects in a Data Model 
         [0033]    A system can provide a common schema that users can extend. Individual subscribers can customize a database using definitions available on a marketplace. 
         [0034]    For example, in a multi-tenant environment, two service providers may install objects with the same name or that use a common shared data model. Where a common schema is defined, the schema allows multiple applications to be installed and work together. In this way, a customer is not stuck with a particular schema. They can extend it. In one implementation, individual applications can also extend the schema. 
         [0035]    In one embodiment, a system similar to the one described above tracks changes to the metadata (e.g., the data defining a schema). In this way, individual subscribers can have their own view (or a modified view) of an object (like a Purchase Order) based on a common shared infrastructure. These views and other metadata may be provided and/or defined by the marketplace. 
         [0036]    The marketplace and related application interface provide a better user experience. In one example, as described above, two applications have one schema. The applications present the data in very different ways and each extend the schema in different ways 
         [0037]    System Overview 
         [0038]      FIG. 1  illustrates a block diagram of an environment  610  wherein an on-demand database service might be used. Environment  610  may include user systems  612 , network  614 , system  616 , processor system  617 , application platform  618 , network interface  620 , tenant data storage  622 , system data storage  624 , program code  626 , and process space  628 . In other embodiments, environment  610  may not have all of the components listed and/or may have other elements instead of, or in addition to, those listed above. 
         [0039]    Environment  610  is an environment in which an on-demand database service exists. User system  612  may be any machine or system that is used by a user to access a database user system. For example, any of user systems  612  can 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. 1  (and in more detail in  FIG. 2 ) user systems  612  might interact via a network  614  with an on-demand database service, which is system  616 . 
         [0040]    An on-demand database service, such as system  616 , 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, “on-demand database service  616 ” and “system  616 ” 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). Application platform  618  may be a framework that allows the applications of system  616  to run, such as the hardware and/or software, e.g., the operating system. In an embodiment, on-demand database service  616  may include an application platform  618  that 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  612 , or third party application developers accessing the on-demand database service via user systems  612 . 
         [0041]    The users of user systems  612  may differ in their respective capacities, and the capacity of a particular user system  612  might be entirely determined by permissions (permission levels) for the current user. For example, where a salesperson is using a particular user system  612  to interact with system  616 , that user system has the capacities allotted to that salesperson. However, while an administrator is using that user system to interact with system  616 , that user system 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. 
         [0042]    Network  614  is any network or combination of networks of devices that communicate with one another. For example, network  614  can 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 present invention might use are not so limited, although TCP/IP is a frequently implemented protocol. 
         [0043]    User systems  612  might communicate with system  616  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, user system  612  might include an HTTP client commonly referred to as a “browser” for sending and receiving HTTP messages to and from an HTTP server at system  616 . Such an HTTP server might be implemented as the sole network interface between system  616  and network  614 , but other techniques might be used as well or instead. In some implementations, the interface between system  616  and network  614  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. 
         [0044]    In one embodiment, system  616 , shown in  FIG. 1 , implements a web-based customer relationship management (CRM) system. For example, in one embodiment, system  616  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 user systems  612  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, system  616  implements applications other than, or in addition to, a CRM application. For example, system  616  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  618 , 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  616 . 
         [0045]    One arrangement for elements of system  616  is shown in  FIG. 2 , including a network interface  620 , application platform  618 , tenant data storage  622  for tenant data  623 , system data storage  624  for system data  625  accessible to system  616  and possibly multiple tenants, program code  626  for implementing various functions of system  616 , and a process space  628  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 system  616  include database indexing processes. 
         [0046]    Several elements in the system shown in  FIG. 2  include conventional, well-known elements that are explained only briefly here. For example, each user system  612  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. User system  612  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 user system  612  to access, process and view information, pages and applications available to it from system  616  over network  614 . Each user system  612  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 system  616  or other systems or servers. For example, the user interface device can be used to access data and applications hosted by system  616 , 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. 
         [0047]    According to one embodiment, each user system  612  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, system  616  (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 processor system  617 , 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 system  616  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 of the present invention 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.). 
         [0048]    According to one embodiment, each system  616  is configured to provide webpages, forms, applications, data and media content to user (client) systems  612  to support the access by user systems  612  as tenants of system  616 . As such, system  616  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. 
         [0049]      FIG. 2  also illustrates environment  610 . However, in  FIG. 2  elements of system  616  and various interconnections in an embodiment are further illustrated.  FIG. 2  shows that user system  612  may include processor system  612 A, memory system  612 B, input system  612 C, and output system  612 D.  FIG. 2  shows network  614  and system  616 .  FIG. 2  also shows that system  616  may include tenant data storage  622 , tenant data  623 , system data storage  624 , system data  625 , User Interface (UI)  730 , Application Program Interface (API)  732 , PL/SOQL  734 , save routines  736 , application setup mechanism  738 , applications servers  7001 - 700 N, system process space  702 , tenant process spaces  704 , tenant management process space  710 , tenant storage area  712 , user storage  714 , and application metadata  716 . In other embodiments, environment  610  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. 
         [0050]    User system  612 , network  614 , system  616 , tenant data storage  622 , and system data storage  624  were discussed above in  FIG. 2 . Regarding user system  612 , processor system  612 A may be any combination of one or more processors. Memory system  612 B may be any combination of one or more memory devices, short term, and/or long term memory. Input system  612 C may be any combination of input devices, such as one or more keyboards, mice, trackballs, scanners, cameras, and/or interfaces to networks. Output system  612 D may be any combination of output devices, such as one or more monitors, printers, and/or interfaces to networks. As shown by  FIG. 2 , system  616  may include a network interface  620  (of  FIG. 2 ) implemented as a set of HTTP application servers  700 , an application platform  618 , tenant data storage  622 , and system data storage  624 . Also shown is system process space  702 , including individual tenant process spaces  704  and a tenant management process space  710 . Each application server  700  may be configured to tenant data storage  622  and the tenant data  623  therein, and system data storage  624  and the system data  625  therein to serve requests of user systems  612 . The tenant data  623  might be divided into individual tenant storage areas  712 , which can be either a physical arrangement and/or a logical arrangement of data. Within each tenant storage area  712 , user storage  714  and application metadata  716  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 user storage  714 . Similarly, a copy of MRU items for an entire organization that is a tenant might be stored to tenant storage area  712 . A UI  730  provides a user interface and an API  732  provides an application programmer interface to system  616  resident processes to users and/or developers at user systems  612 . The tenant data and the system data may be stored in various databases, such as one or more Oracle™ databases. 
         [0051]    Application platform  618  includes an application setup mechanism  738  that supports application developers&#39; creation and management of applications, which may be saved as metadata into tenant data storage  622  by save routines  736  for execution by subscribers as one or more tenant process spaces  704  managed by tenant management process  710  for example. Invocations to such applications may be coded using PL/SOQL  734  that provides a programming language style interface extension to API  732 . 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 DATABASE ON-DEMAND DATABASE SERVICE issued Jun. 1, 2010 to Craig Weissman, 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 application metadata  716  for the subscriber making the invocation and executing the metadata as an application in a virtual machine. 
         [0052]    Each application server  700  may be communicably coupled to database systems, e.g., having access to system data  625  and tenant data  623 , via a different network connection. For example, one application server  7001  might be coupled via the network  614  (e.g., the Internet), another application server  700 N- 1  might be coupled via a direct network link, and another application server  700 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  700  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. 
         [0053]    In certain embodiments, each application server  700  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  700 . 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  700  and the user systems  612  to distribute requests to the application servers  700 . In one embodiment, the load balancer uses a least connections algorithm to route user requests to the application servers  700 . 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  700 , and three requests from different users could hit the same application server  700 . In this manner, system  616  is multi-tenant, wherein system  616  handles storage of, and access to, different objects, data and applications across disparate users and organizations. 
         [0054]    As an example of storage, one tenant might be a company that employs a sales force where each salesperson uses system  616  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 tenant data storage  622 ). 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. 
         [0055]    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 system  616  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, system  616  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. 
         [0056]    In certain embodiments, user systems  612  (which may be client systems) communicate with application servers  700  to request and update system-level and tenant-level data from system  616  that may require sending one or more queries to tenant data storage  622  and/or system data storage  624 . System  616  (e.g., an application server  700  in system  616 ) automatically generates one or more SQL statements (e.g., one or more SQL queries) that are designed to access the desired information. System data storage  624  may generate query plans to access the requested data from the database. 
         [0057]    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 according to the present invention. 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”. 
         [0058]    While the invention has been described by way of example and in terms of the specific embodiments, it is to be understood that the invention is 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.