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Teradata RDBMS forUNIX SQL Reference - NCR

NCR Teradata RDBMS forUNIX SQL Reference - NCR, 1997. - 913 p.
Download (direct link): teradataforunix1997.pdf
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The following performance enhancements are available:

• Parallel Query Processing

DB2 can now split the query processing on more than one central processor within a CPC to improve query performance.

• DB2 Catalog Operations

Teradata RDBMS for UNIX SQL Reference C-13
Comparing Teradata SQL and DB2

DB2 Version 4.0 Changes

New indexes on the DB2 catalog improve performance os some operations. User’s own indexes can be created on catalog tables and values of PCTFREE and FREEPAGE can be changed on existing catalog tables. REORG utility can be run on most table spaces in the catalog and directory to reclaim unused space.

• Utility Performance

The following utilities have been enhanced or improved:

• COPY, LOAD, and REORG

• RUNSTATS

• More utility buffers by default

• The work data set can be eliminated for RECOVER INDEX

• DB2 can limit table space scan to a subset of partitions

• Some SQL queries are processed faster

• Monitoring the DB2 database I/Os has improved with addition of DB2 I/O information in SMF type 30 records.

The following features are supported in DB2, Version 4:

User Productivity ^

• Operations

• Multiple-character command prefixes remove the restriction of a single character recognition character. Up to 8 characters can be prefixed.

• DFSMS concurrent copy can be invoked from the DB2 COPY utility, and these copies can be used for backup and recovery.

• Logical page list replaces the write error range for transient I/O errors and replaces the DEFERRED status in restarts. If a page cannot be read or written, it is added to this logical page list, leaving the rest of the data available.

• Compressed Log Data. Log data of table spaces compressed by DB2 can be read.

• Done-level page sets detection increases usability, reliability of backup operations done outside DB2, such as DSN1COPY.

• CANCEL thread is a new command enabling user to cancel all threads in the same way as done with DDF threads using CANCEL DDF THREAD command.

• Other improvements allow:

• Restart RECOVER INDEX at the beginning of a phase

• Create four merged copies of a table space‘

• Use copies created at either the local or recovery site for RECOVER TABLESPACE operations

• Prevent Accidental dropping of a table by using new SQL syntax.

C-14

Teradata RDBMS for UNIX SQL Reference
Comparing Teradata SQL and DB2

DB2 Version 4.0 Changes

• Application Programming

• Outer joins

• Table check constraints

• User-defined defaults

• Other enhancements :

• The AS clause allowing results columns to be named and used, e.g., in the ORDER BY clause

• Nested table expressions

• A short way to define single-column keys.

• Removal of restrictions that do not allow cursor-controlled updates of the primary key, and cursor controlled deletions of self-referencing constraints.

• To conform with Standards, a stand-alone SQLSTATE host variable declared and used in an application program now exists. Also there are new SQLSTATE values which conform to ANSI/ISO SQL Standard, 1992.

• CURRENT RULES register specifies which SQL statements are executed in accordance with usual DB2 rules or within the ANSI/ISO SQL standard of 1992.

• UNIQUE WHERE NOT NULL clause on CREATE INDEX for type 2 index specifies that the uniqueness constraint does not apply to the key value if any column of the key is null.

• Syntax extensions to enable greater compatibility and conformance to ANSI/ISO SQL standard of 1992.

• DBCS support for C and PL/I programs

• Support for the C decimal data type

• Extension of the DECIMAL function to allow a character string as the first argument

• Authorization

• A new bind option, DYNAMICRULES, allows the specification for dynamic SQL that a plan or package owner’s authority should be used to access DB2 resources, i.e., users only need a single authorization ID for applications using both static and dynamic SQL.

• Holder of DBMAINT authority can terminate utility jobs.

• Authorities for creating new packages, or new versions of existing packages are less restrictive.

Teradata RDBMS for UNIX SQL Reference

C-15
Comparing Teradata SQL and DB2

DB2 Extensions Not Supported in Teradata SQL

DB2 Extensions Not Supported in Teradata SQL

Introduction

This section describes DB2 features and functions that are not supported by Teradata SQL. These features and functions can be considered as DB2 extensions.

MultiSorting Nulls

Teradata SQL sorts nulls after all other data in a column. DB2 sorts nulls before any other data in a column.

Syntax Differences

The following is a list of DB2 commands not offered in Teradata SQL, and differences between DB2 and Teradata SQL, listed alphabetically:

ALTER INDEX

Named indexes are now supported in Teradata SQL. The procedure for renaming named indexes differs.

ALTER STOGROUP

ALTER TABLE

This is not supported in Teradata SQL.
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