Db2 12 z/OS DBA key terms

A single running instance of Db2 for z/OS, identified by a four-character SSID, with its own catalog, directory, log, and address spaces such as DBM1, MSTR, and DIST.

The Db2 subsystem address space that manages startup and shutdown, log processing, and attachment coordination; it also owns critical functions such as command processing and restart logic.

The Db2 address space that contains most database services, including buffer pools, EDM pools, and the RDS, and where SQL statement execution and data manager activity take place.

The Internal Resource Lock Manager address space that provides locking services for Db2, including lock escalation, deadlock detection, and lock suspension, and can be shared across data sharing members.

The Db2 subsystem's internal catalog of objects and their definitions, containing SYSIBM.SYSCOPY, SYSIBM.SYSUTILX, and other directory tables; it is not user-accessible via normal SQL.

The Db2 database that holds the user-visible catalog tables, such as SYSIBM.SYSTABLES, SYSIBM.SYSCOLUMNS, and SYSIBM.SYSINDEXES, which describe database objects and privileges.

A set of Db2 subsystems on different z/OS images that access the same databases concurrently, coordinating through a coupling facility for locks, buffers, and shared communication.

A z/OS component that provides shared memory structures used by Db2 data sharing, including lock structures, group buffer pools, and shared communications areas for member coordination.

A coupling facility structure that caches pages shared among data sharing members, allowing pages to be read and written without forcing immediate disk I/O to the shared database.

The Db2 mechanism that tracks which objects are in use and waits for current users to release them before allowing disruptive operations such as DROP, ALTER, or REORG to proceed.

A memory area in the DBM1 address space that caches table space and index pages to reduce disk I/O; its size and thresholds strongly affect application performance.

The environment descriptor management pool in DBM1 that holds skeletons and plans for cached dynamic and static SQL statements, influencing prepare and execution efficiency.

A Db2 facility that stores prepared dynamic SQL statements so repeated executions can reuse access paths, reducing prepare cost and CPU consumption for similar statements.

The Db2 process that validates SQL and produces an application plan or package containing access paths and authorization information used at execution time.

A compiled collection of SQL statements stored in the catalog, produced by binding a DBRM, and referenced by a plan or by collection and package name at execution.

The Db2 feature that lets a DBA capture and reuse a previously bound access path, reducing performance regressions when statistics or the optimizer change.

The Db2 utility that collects table, column, and index statistics in the catalog, giving the optimizer the data it needs to choose efficient access paths.

A Db2 utility that reorganizes table space or index data to remove fragmentation and restore clustering, and can run online while limiting outages.

A Db2 REORG execution mode that allows concurrent read and write access during most of the reorganization, using shadow data sets and a final short switch phase.

A Db2 utility that produces image copies of table spaces or data sets, either full or incremental, which are used for recovery and for satisfying object recovery requirements.

A Db2 utility that restores a table space or index from image copies and then applies log records to bring it to a consistent point in time.

A physical snapshot of a table space or index data set produced by COPY or a vendor tool, registered in SYSIBM.SYSCOPY and used as the base for recovery.

A Db2 directory table that records image copies, log ranges, and other recovery information needed by RECOVER and by Db2 to determine whether objects are recoverable.

Restoring a Db2 object to a specific timestamp or log point rather than to the current state, typically by applying log records only up to the chosen point.

The set of Db2 log data sets currently being written and retained online, containing recent changes needed for restart and rollback before being archived.

Copies of Db2 active log data sets moved to offload storage, retained for recovery to earlier points and for log-based replication or change capture.

A recorded point in Db2 processing that captures subsystem state and log position, used during restart to determine where processing must resume.

The process by which Db2 resumes an interrupted utility from its last checkpoint, using information in SYSIBM.SYSUTILX to avoid redoing completed work.

A Db2 directory table that tracks utility execution state and restart information, allowing Db2 to identify and restart utilities that were interrupted.

A SQL query against Db2 catalog tables that reveals object definitions, statistics, privileges, and dependencies, commonly used for impact analysis and administration.

A Db2 constraint that ensures values in a foreign key column match a primary or unique key value in a parent table, enforced by Db2 during data changes.

A rule attached to a table that limits allowed column values, verified by Db2 on insert and update operations and used to keep data within business rules.

A Db2 storage unit that contains one or more tables and maps them to physical data sets, with types such as partitioned, segmented, and universal.

A table space divided into partitions by ranges of a partitioning key, enabling partition-level utilities, queries, and availability management.

A program registered in Db2 and invoked by SQL CALL, running in a stored procedure address space or WLM environment to reduce network traffic and centralize logic.

A z/OS workload manager address space configuration used to execute Db2 stored procedures and user-defined functions under defined service and resource controls.

SQL statements that give or remove Db2 privileges on objects or administrative authorities, recorded in the catalog and enforced at bind and execution time.

A named collection of Db2 privileges that can be granted to users or groups, simplifying administration and allowing privileges to be managed centrally.

A Db2 rule that allows a middle-tier server to establish a connection on behalf of an end user with specific privileges, based on defined trust attributes.

A Db2 trace that records authorization and privilege-related activity, such as failed access attempts, for security monitoring and compliance review.

An identifier for a specific Db2 trace record type, used when starting traces and interpreting performance or audit data collected by Db2 instrumentation.

A Db2 trace that reports resource consumption by application, such as CPU, elapsed time, and lock waits, used for chargeback and performance tuning.