See the glossary in the Adaptive Server documentation for a complete list of Adaptive Server terms.
Adaptive Server – a server in the Sybase client/server architecture that manages
multiple databases and multiple users, keeps track of the actual location of
data on disks, maintains mapping of logical data description to physical
data storage, and maintains data and procedure caches in memory. Sybase
Control Center can manage multiple Adaptive Servers.
alert
– a mechanism for notifying administrators when a managed
resource experiences a status change, or when a performance metric passes a
user-specified threshold.
alert notification
– an indication that an alert has fired. Alert notifications
appear in the Alert Monitor view. If e-mail notification is enabled, alert
notifications are also delivered to the specified e-mail address.
alert storm
– the result of issuing many redundant alerts associated with a
common or root occurrence. See also alert storm suppression.
alert storm suppression
– a Sybase Control Center feature that can be configured to
prevent alert storms by suppressing repeat alert notifications for a
specified period of time.
alert type
– the basis on which an alert fires: state or threshold. State
alerts are triggered by the state of their key performance indicator (for
example, running or stopped), while threshold alerts are triggered when
their KPI’s numerical value passes a specified threshold.
authenticate – when SCC authenticates with a managed resource, it logs in to
the resource with a user ID and password provided by you. SCC must log in to
managed resources in order to gather performance statistics and perform
management tasks. You can choose to have SCC use your current SCC login ID,
or you can provide different credentials.
availability
– indicates whether a resource is accessible and responsive.
blocking – waiting for a lock; a task that needs to acquire a lock on a
row, page, or table must wait, or block, if another process holds an
incompatible lock on its target object.
cache – See data cache, procedure cache, or statement cache.
chart trend period – the period, in minutes, over which data is displayed in
historical charts. Set the chart trend period on the Settings screen of the
Adaptive Server monitor. Contrast with screen refresh interval.
collection
– a named, predefined set of key performance indicators for which
values are collected from monitored servers at the same time. Collections
supply the performance and availability data shown on Sybase Control Center
screens and charts. Use the scheduler to view a list of collections and to
control which collections run, how often they run, and the length of time
for which they run.
collection repeat interval – the period, in seconds, between successive repetitions of a
statistics collection job. The collection repeat interval determines how
often new data on historical monitoring screens is available to be
refreshed. Set the collection repeat interval in the scheduler. See also
screen refresh interval.
data cache –
also called buffer cache and
named cache. An area of memory within Adaptive Server that contains the
images of database pages and the data structures required to manage the
pages. Each cache is given an unique name that is used for configuration
purposes. By default, Adaptive Server has a single cache named “default data
cache.” Caches configured by users are called user-defined caches.
device – in Adaptive Server, any piece of a disk or file in the file
system used to store databases and their component objects.
engine – an instance of the Adaptive Server executable that can
communicate with other Adaptive Server engines in shared memory. An Adaptive
Server running on a uniprocessor machine always has one engine, engine 0. An
Adaptive Server running on a multiprocessor machine can have one or more
engines.
event
– an activity in the system, such as a user logging in, a service
starting or stopping, or a condition changing. Use the alerts feature to
detect and notify you about system events.
extent – a block of 8
Adaptive Server pages. The size of an extent depends on the page size the
server uses. The extent size on a 2K server is 16K; on an 8K it is 64K, and
so on. The smallest amount of space that a table or index can occupy is 1
extent, or 8 pages. Extents are deallocated only when all the pages in an
extent are empty.
heat chart
– a graphical view of resource availability and selected
performance and status metrics for all the registered resources in the
current perspective.
index – a database object that consists of key values from data tables
and pointers to the pages that contain those values. Indexes speed up access
to data rows by pointing Adaptive Server to the location of a table columns
data on disk.
instance – an SCC agent or server run from a shared disk installation. See
also shared-disk mode.
job
– a task performed by the scheduler in Sybase Control
Center.
key performance indicator (KPI)
–
a single metric used to evaluate the status or performance of a
monitored resource. A KPI value can be a state (such as running, error, or
stopped) or a numerical value. KPIs are grouped into collections (and also,
for some product modules, into key performance areas, or KPAs). KPI values
are collected by scheduled collection jobs and appear on monitoring screens
and in the statistics and heat charts. Examples of KPIs are resource state
and CPU usage.
lock – a concurrency control mechanism that protects the integrity of
data and transaction results in a multiuser environment. Adaptive Server
applies table, page, and row locks to:
- Prevent two or more users from changing the same
data at the same time
- Prevent processes from reading data that is in the
process of being changed
managed
resource – see resource.
message row – a row that appears in the right pane of the Administration
Console in place of a slow-responding request, a failed request, or a large
result set. Rows with slow-responding requests are populated as soon as the
data arrives. You can retry failed requests or expand large result
sets—select the row and click the drop-down arrow to see
options.
perspective
– a named tab in Sybase Control Center that displays information
related to a collection of managed resources (such as servers) and a set of
views associated with those resources. The views in a perspective are chosen
by users of the perspective. You can create as many perspectives as you
need, and customize them to monitor and manage your resources. Perspectives
allow you to group resources in ways that make sense in your environment—for
example by location, department, or project.
procedure cache – memory used for stored procedures, batch query plans, triggers,
the statement cache, datachange tracking, query compilation, and other
objects used during query execution.
product module – a
plug-in component of Sybase Control Center that manages and monitors a
particular Sybase product. SCC product modules are available for Adaptive Server, Data Assurance (a Replication Server
option), replication (Replication Server, Replication Agent, and Mirror Replication
Agent), Sybase Event Stream Processor, and Sybase IQ.
query plan – the ordered set of steps required to carry out a SQL query,
complete with the access methods chosen for each table. Query plans are
chosen by the Adaptive Server optimizer.
repository
– a database in Sybase Control Center that stores information
related to managed resources, along with user preference data, operational
data, and performance statistics.
resource
–
a server,
agent, or other entity that can be monitored or administered by Sybase
Control Center. Resources SCC can manage include Adaptive Server, Data Assurance Server,
Replication Server, Replication Agent, Mirror Replication Agent, Sybase Event Stream
Processor, Sybase IQ, and certain subcomponents.
SCC-enabled login account
– a user account that has been granted privileges in Sybase
Control Center by mapping appropriate Sybase Control Center roles. (Roles
are typically mapped to a group to which the account belongs rather than to
the account itself.) The user account and group can be native to Sybase
Control Center or created in the operating system or the LDAP directory
service to which Sybase Control Center authentication is delegated. You must
use an SCC-enabled account to log in to Sybase Control Center.
SCC agent – a remote command and control agent for Sybase Control Center
that runs on a managed server. The SCC agent is installed automatically as
part of the Sybase server.
schedule – the definition of a task (such as the collection of a set of
statistics) and the time interval at which Sybase Control Center executes
the task.
screen refresh interval – the period in seconds between refreshes of screens in the
Adaptive Server component of Sybase Control Center. Refreshing a screen
redraws it with the most recent available data. Set the screen refresh
interval on the Settings screen of the Adaptive Server monitor. See also
collection repeat interval.
segment – space allocated on one or more database devices. Segments can
be used to control the placement of tables and indexes on specific database
devices.
semaphore – a simple internal locking mechanism that prevents a second task
from accessing the data structure currently in use. Adaptive Server uses
semaphores to protect transaction logs, user log caches, and I/O devices. A
semaphore is relevant only in symmetric multiprocessing (SMP)
environments.
shared-disk mode – a feature that enables multiple instances of Sybase Control
Center to execute from a single installation on a shared disk. Instances can
be SCC servers, agents, or a mixture of the two.
singleton
installation – a Sybase Control Center installation that runs a single SCC
agent or server. Contrast with instance; see also shared-disk mode.
statement cache – memory used to store computed query plans. The statement cache
is part of the procedure cache.
transaction – a set of related SQL statements that are treated as a single
unit of work. To ensure consistency, if all the statements in the set cannot
be executed, the changes made by the query are rolled back. The tables
queried during the transaction are locked until a transaction is
completed.
Transact-SQL – the SQL dialect used in Sybase Adaptive Server.
trend period – See chart trend period.
view (Adaptive Server) – a named select statement
that is stored in the database as an object. A view lets you see a subset of
rows or columns from one or more tables. Contrast with view (SCC).
view (SCC)
– a window in a Sybase Control Center perspective that displays
information about one or more managed resources. Some views also let you
interact with managed resources or with SCC itself. For example, the
Perspective Resources view lists all the resources managed by the current
perspective. Other views allow you to configure alerts, view the topology of
a replication environment, and graph performance statistics.
wait event – a condition that causes an Adaptive Server process to pause and
wait for another event. Common wait events are waiting for disk I/O to
complete, waiting on the Adaptive Server scheduler runnable queue for a CPU
to become available, and waiting for another processes lock on a table to be
released.