Glossary

This glossary describes Sybase Replication Agent terms used in this book.

Adaptive Server

The brand name for Sybase relational database management system (RDBMS) software products.

  • Adaptive Server Enterprise manages multiple, large relational databases for high-volume online transaction processing (OLTP) systems and client applications.

  • Adaptive Server IQ manages multiple, large relational databases with special indexing algorithms to support high-speed, high-volume business intelligence, decision support, and reporting client applications.

  • Adaptive Server Anywhere manages relational databases with a small DBMS footprint, which is ideal for embedded applications and mobile device applications.

See also DBMS and RDBMS.

atomic materialization

A materialization method that copies subscription data from a primary database to a standby database in a single, atomic operation. No changes to primary data are allowed until the subscription data is captured at the primary database. See also bulk materialization and nonatomic materialization.

BCP utility

A bulk copy transfer utility that provides the ability to load multiple rows of data into a table in a target database. See also bulk copy.

bulk copy

An Open Client interface for the high-speed transfer of data between a database table and program variables. It provides an alternative to using SQL insert and select commands to transfer data.

bulk materialization

A materialization method whereby subscription data in a standby database is initialized outside of the replication system. You can use bulk materialization for subscriptions to table replication definitions or function replication definitions. See also atomic materialization and nonatomic materialization.

client

In client/server systems, the part of the system that sends requests to servers and processes the results of those requests. See also client application.

client application

Software that is responsible for the user interface, including menus, data entry screens, and report formats. See also client.

commit

An instruction to the DBMS to make permanent the changes requested in a transaction. See also transaction. Contrast with rollback.

data client

A client application that provides access to data by connecting to a data server. See also client, client application, and data server.

data distribution

A method of locating (or placing) discrete parts of a single set of data in multiple systems or at multiple sites. Data distribution is distinct from data replication, although a data replication system can be used to implement or support data distribution. Contrast with data replication.

data replication

The process of copying data to remote locations, and then keeping the replicated data synchronized with the primary data. Data replication is distinct from data distribution. Replicated data is stored copies of data at one or more remote sites throughout a system, and it is not necessarily distributed data. Contrast with data distribution. See also disk replication and transaction replication.

data server

A server that provides the functionality necessary to maintain the physical representation of a table in a database. Data servers are usually database servers, but they can also be any data repository with the interface and functionality a data client requires. See also client, client application, and data client.

database

A collection of data with a specific structure (or schema) for accepting, storing, and providing data for users. See also data server, DBMS, and RDBMS.

database connection

A connection that allows Replication Server to manage the database and distribute transactions to the database. Each database in a replication system can have only one database connection in Replication Server. See also Replication Server and route.

datatype

A keyword that identifies the characteristics of stored information on a computer. Some common datatypes are: char, int, smallint, date, time, numeric, and float. Different data servers support different datatypes.

DBMS

An abbreviation for database management system, a computer-based system for defining, creating, manipulating, controlling, managing, and using databases. The DBMS can include the user interface for using the database, or it can be a stand-alone data server system. Compare with RDBMS.

disaster recovery

A method or process used to restore the critical business functions interrupted by a catastrophic event. A disaster recovery (or business continuity) plan defines the resources and procedures required for an organization to recover from a disaster, based on specified recovery objectives.

ERSSD

An abbreviation for embedded Replication Server System Database, which manages replication system information for a Replication Server. See also Replication Server.

failback

A procedure that restores the normal user and client access to a primary database, after a failover procedure switched access from the primary database to a standby database.See also failover.

failover

A procedure that switches user and client access from a primary database to a standby database, particularly in the event of a failure that interrupts operations at the primary database, or access to the primary database. Failover is an important fault-tolerance feature for systems that require high availability. See also failback.

function

A Replication Server object that represents a data server operation such as insert, delete, or begin transaction. Replication Server distributes operations to standby databases as functions. See also function string.

function string

A string that Replication Server uses to map a function and its parameters to a data server API. Function strings allow Replication Server to support heterogeneous replication, in which the primary and standby databases are different types, with different SQL extensions and different command features. See also function.

gateway

Connectivity software that allows two or more computer systems with different network architectures to communicate.

inbound queue

A stable queue managed by Replication Server to spool messages received from a Sybase Replication Agent. See also outbound queue and stable queue.

interfaces file

A file containing information that Sybase Open Client and Open Server applications need to establish connections to other Open Client and Open Server applications. See also Open Client and Open Server.

isql

An interactive SQL client application that can connect and communicate with any Sybase Open Server application, including Adaptive Server, Sybase Replication Agent, and Replication Server. See also Open Client and Open Server.

Java

An object-oriented programming language developed by Sun Microsystems. A platform-independent, “write once, run anywhere” programming language.

Java VM

The Java Virtual Machine. The Java VM (or JVM) is the part of the Java Runtime Environment (JRE) that is responsible for interpreting Java byte codes. See also Java and JRE.

JDBC

An abbreviation for Java Database Connectivity. JDBC is the standard communication protocol for connectivity between Java clients and data servers. See also data server and Java.

JRE

An abbreviation for Java Runtime Environment. The JRE consists of the Java Virtual Machine (Java VM or JVM), the Java Core Classes, and supporting files. The JRE must be installed on a machine to run Java applications, such as the Sybase Replication Agent. See also Java VM.

LAN

An abbreviation for “local area network,” a computer network located on the user’s premises that covers a limited geographical area (usually a single site). Communication within a local area network is not subject to external regulations; however, communication across the LAN boundary can be subject to some form of regulation. Contrast with WAN.

latency

In transaction replication, the time it takes to replicate a transaction from a primary database to a standby database. Specifically, latency is the time elapsed between committing an original transaction in the primary database and committing the replicated transaction in the standby database.

In disk replication, latency is the time elapsed between a disk write operation that changes a block or page on a primary device and the disk write operation that changes the replicated block or page on a mirror (or standby) device.

See also disk replication and transaction replication.

LOB

An abbreviation for large object, a type of data element that is associated with a column that contains extremely large quantities of data.

Log Reader

An internal component of the Sybase Replication Agent that interacts with the primary database and mirror log devices to capture transactions for replication. See also Log Transfer Interface and Log Transfer Manager.

Log Transfer Interface

An internal component of the Sybase Replication Agent that interacts with Replication Server to forward transactions for distribution to a standby database. See also Log Reader and Log Transfer Manager.

Log Transfer Manager

An internal component of the Sybase Replication Agent that interacts with the other Sybase Replication Agent internal components to control and coordinate Sybase Replication Agent operations. See also Log Reader and Log Transfer Interface.

Maintenance User

A special user login name in the standby database that Replication Server uses to apply replicated transactions to the database. See also Replication Server.

materialization

The process of copying the data from a primary database to a standby database, initializing the standby database so that the Sybase Replication Agent system can begin replicating transactions. See also atomic materialization, bulk materialization, and non-atomic materialization.

nonatomic materialization

A materialization method that copies subscription data without a lock on the primary database. Changes to primary data are allowed during data transfer, which may cause temporary inconsistencies between the primary and standby databases. Contrast with atomic materialization. See also bulk materialization.

ODBC

An abbreviation for Open Database Connectivity, an industry standard communication protocol for clients connecting to data servers. See also JDBC.

Open Client

A Sybase product that provides customer applications, third-party products, and other Sybase products with the interfaces needed to communicate with Open Server applications. See also Open Server.

Open Client application

An application that uses Sybase Open Client libraries to implement Open Client communication protocols. See also Open Client and Open Server.

Open Server

A Sybase product that provides the tools and interfaces required to create a custom server. See also Open Client.

Open Server application

A server application that uses Sybase Open Server libraries to implement Open Server communication protocols. See also Open Client and Open Server.

outbound queue

A stable queue managed by Replication Server to spool messages to a standby database. See also inbound queue and stable queue.

primary data

The version of a set of data that is the source used for replication. Primary data is stored and managed by the primary database. See also Sybase Replication Agent, primary database, and Replication Server.

primary database

The database that contains the data to be replicated to another database (the standby database) through a replication system. The primary database is the database that is the source of replicated data in a replication system. Sometimes called the active database. Contrast with standby database. See also primary data.

primary key

The column or columns whose data uniquely identify each row in a table.

primary site

The location or facility at which primary data servers and primary databases are deployed to support normal business operations. Sometimes called the active site or main site. See also primary database and standby site.

primary table

A table used as a source for replication. Primary tables are defined in the primary database schema. See also primary data and primary database.

primary transaction

A transaction that is committed in the primary database and recorded in the primary database transaction log. See also primary database, replicated transaction, and transaction log.

quiesce

To cause a system to go into a state in which further data changes are not allowed. See also quiescent.

quiescent

In a replication system, a state in which all updates have been propagated to their destinations. Some Sybase Replication Agent and Replication Server commands require that you first quiesce the replication system.

In a database, a state in which all data updates are suspended so that transactions cannot change any data and the data and log devices are stable.

This term is interchangeable with quiesced and in quiesce. See also quiesce.

RASD

An abbreviation for Replication Agent System Database. Information in the RASD is used by the primary database to recognize database structure or schema objects in the transaction log.

RCL

An abbreviation for Replication Command Language, the command language used to manage Replication Server.

RDBMS

An abbreviation for relational database management system, an application that manages and controls relational databases. Compare with DBMS. See also relational database.

relational database

A collection of data in which data is viewed as being stored in tables, which consist of columns (data items) and rows (units of information). Relational databases can be accessed by SQL requests. See also SQL.

replicated data

A set of data that is replicated from a primary database to a standby database by a replication system. See also primary database, replication system, and standby database.

replicated transaction

A primary transaction that is replicated from a primary database to a standby database by a transaction replication system. See also primary database, primary transaction, standby database, and transaction replication.

Replication Agent

An application that reads a primary database transaction log to acquire information about data-changing transactions in the primary database, processes the log information, and then sends it to a Replication Server for distribution to a standby database. See also primary database and Replication Server.

replication definition

A description of a table or stored procedure in a primary database, for which subscriptions can be created. The replication definition, maintained by Replication Server, includes information about the columns to be replicated and the location of the primary table or stored procedure. See also Replication Server and subscription.

Replication Server

The Sybase software product that provides the infrastructure for a robust transaction replication system. See also Replication Agent.

RSSD

An abbreviation for Replication Server System Database, which manages replication system information for a Replication Server. See also Replication Server.

replication system

A data processing system that replicates data from one location to another. Data can be replicated between separate systems at a single site, or from one or more local systems to one or more remote systems. See also disk replication and transaction replication.

rollback

An instruction to a database to back out of the changes requested in a unit of work (called a transaction). Contrast with commit. See also transaction.

SQL

An abbreviation for Structured Query Language, a non-procedural programming language used to process data in a relational database. ANSI SQL is an industry standard. See also transaction.

stable queue

A disk device-based, store-and-forward queue managed by Replication Server. Messages written into the stable queue remain there until they can be delivered to the appropriate process or standby database. Replication Server provides a stable queue for both incoming messages (the inbound queue) and outgoing messages (the outbound queue). See also database connection, Replication Server, and route.

standby data

The data managed by a standby database, which is the destination (or target) of a replication system. See also data replication and standby database.

standby database

A database that contains data replicated from another database (the primary database) through a replication system. The standby database is the database that receives replicated data in a replication system. Sometimes called the replicate database. Contrast with primary database. See also standby data.

standby site

The location or facility at which standby data servers and standby databases are deployed to support disaster recovery, and normal business operations during scheduled downtime at the primary site. Sometimes called the alternate site or replicate site. Contrast with primary site. See also standby database.

subscription

A request for Replication Server to maintain a replicated copy of a table, or a set of rows from a table, in a standby database at a specified location. See also replication definition and Replication Server.

table

In a relational DBMS, a two-dimensional array of data or a named data object that contains a specific number of unordered rows composed of a group of columns that are specific for the table. See also database.

transaction

A unit of work in a database that can include zero, one, or many operations (including insert, update, and delete operations), and that is either applied or rejected as a whole. Each SQL statement that modifies data can be treated as a separate transaction, if the database is so configured. See also SQL.

transaction log

Generally, the log of transactions that affect the data managed by a data server. Sybase Replication Agent reads the transaction log to identify and acquire the transactions to be replicated from the primary database. See also Sybase Replication Agent, primary database, and Replication Server.

transaction replication

A data replication method that copies data-changing operations from a primary database transaction log to a standby database. See also data replication and disk replication.

transactional consistency

A condition in which all transactions in the primary database are applied in the standby database, in the same order that they were applied in the primary database.

WAN

An abbreviation for “wide area network,” a system of local-area networks (LANs) connected together with data communication lines. Contrast with LAN.