This glossary gives you a description of the terminology used in SOLID documentation.
A BLOb is a large block of binary information such as a picture, video clip, sound excerpt, or a formatted text document. BLObs can be saved to and retrieved from SOLID Server.
Checkpoints are used to store a consistent state of the database quickly onto the disk. After a system crash, the database will start recovering transactions from the latest checkpoint. The more frequently checkpoints are made, the fewer transactions need to be recovered from the log file.
Client/server computing divides a large piece of software into modules that need not all be executed within the same memory space nor on the same processor. The calling module becomes the client that requests services, and the called module becomes the server that provides services. Client and server processes exchange information by sending messages through a computer network. They may run on different hardware and software platforms as appropriate for their special functions.
Two basic client/server architecture types are called two-tier and three-tier application architectures.
A communication protocol is a set of rules and conventions used in the communication between servers and clients. The server and client have to use the same communication protocol in order to establish a connection.
The database administrator is a person responsible for tasks such as:
- managing users, tables, and indices
- backing up data
- allocating disk space for the database files
A DBMS is a system that stores information in and retrieves information from a database. A DBMS typically consists of a database server, administration utilities, an application interface, and development tools.
Database procedures allow programmers to split the application logic between the client and the server. These procedures are stored in the database, and they accept parameters in the activation call from the client application. This arrangement is beneficial especially in the case of heavy updates that first require extensive queries and that can be initiated with a small amount of parameter information. In these cases, the network traffic is significantly reduced, and much better performance can be achieved.
In SOLID Server, the execution plan for a stored procedure is stored in a system table with the procedure; thus it need not be recalculated each time the SQL statement is executed.
Event alerts
Events are objects with a name and parameters. Event alerts are used to signal an event in the database. The signal is sent from an application using the POST EVENT command. The signal is received by one or more client applications waiting for the event. The use of event alerts removes resource consuming database polling from applications.
This file holds a log of all committed operations executed by the database server. If a system crash occurs, the database server uses this log to recover all data inserted or modified after the latest checkpoint.
The network name of a server consists of a communication protocol and a server name. This combination identifies the server in the network.
SOLID Clients support Logical Data Source Names. These names can be used to give a database a descriptive name. This name is mapped to a network name using either parameter settings in the clients solid.ini file or in Windows operating systems registry settings. This feature is available on all supported platforms from version 2.2 forward.
ODBC is a programming interface standard for SQL database programs. SOLID Server offers a native ODBC programming interface.
SOLID Server is an RDBMS, which stores and retrieves information that is organized into two-dimensional tables. This name derives from the relational theory that formalizes the data manipulation requests as set operations and allows mathematical analysis of these sets. RDBMSs typically support the SQL language for data manipulation requests.
SAG CLI is a programming interface standard that defines the functions that are used to submit dynamic SQL clauses to a database server for execution. The ODBC interface is also based on SAG CLI. The SOLID SQL API conforms to the SAG CLI standard.
All tables are contained in a higher level construct called schema. It is a place where tables and related objects are gathered together under one qualifying name. For each schema there are zero or more tables, and for each table, there is exactly one schema to which it belongs. The relationship between a schema and its tables is similar to that of an operating system directory and the files contained within that directory.
Table schemas allow several logical databases to reside in the same physical database. A typical use could be to have a similar table structure for each customer in the database of an accounting firm. All the data would still be stored in a single physical database, which allows sharing the common parameter information.
The default directory for storing SOLID DBMS database files. This is either the server programs working directory or alternatively the directory set by the SOLIDDIR environment variable.
SQL is a standardized query language designed for handling database requests and administration. The SQL syntax used in SOLID Server is based on the ANSI X3.135-1989 Level 2 standard including important ANSI X3.135-1992 (SQL2) extensions. For a more formal definition of the syntax, refer to Appendix D SOLID SQL Syntax of SOLID Server Administrator's Guide.
Compared to the two-tier architecture the three-tier architecture has an additional layer or layers of application servers. This allows splitting the application logic between client processes to a specialized application server process handling the resources management, other I/O, or calculation intensive tasks.
Instead of sending small SQL statements the client application sends whole procedures for the application server to be processed. This reduces the number of messages thus minimizing the network load. The application logic is often more easily managed because several applications use centrally maintained procedures.
Generally, the two-tier architecture refers to a client/server system, where a client application containing all the business logic is running on a workstation and a database server is taking care of data management.
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