Download Informix Guide to SQL: Reference

Tech Review Draft Tech Review Draft Tech Review Draft Tech Review Draft Tech Review Draft Tech Review Draft Tech Review Draft Tech
project
A group of related components used by the HPL. See component.
projection
Taking a subset from the columns of a single table. Projection is implemented
through the select list in the SELECT clause of a SELECT statement and returns
some of the columns and all the rows in a table. See selection and join.
promotable lock
A lock that can be changed from a shared lock to an exclusive lock. See update
lock.
protocol
A set of rules that govern communication among computers. These rules
govern format, timing, sequencing, and error control.
query
A request to the database to retrieve data that meets certain criteria, usually
with the SELECT statement. When used with the High Performance Loader,
selects records to unload from a Dynamic Server database. See component.
query
optimization
information
statements
The SQL statements that are used to optimize queries. These statements
include SET EXPLAIN, SET OPTIMIZATION, and UPDATE STATISTICS.
query unnesting
An execution strategy for nested SQL subqueries whereby Dynamic Server
with AD and XP Options rewrites such subqueries to use modified joins
rather than iteration mechanisms. The sqexplain.out file reflects the query
plan that has been selected after subquery unnesting has occurred.
range rule
A user-defined algorithm that you use to define the boundaries of each fragment in a table using SQL relational and logical operators. Expressions in a
range rule can use the following restricted set of operators: >, <, >=, <=, and
the logical operator AND.
raw table
A nonlogged permanent table that uses light appends.
raw device
See unbuffered disk I/O.
raw disk
See unbuffered disk I/O.
Read Committed
An ANSI level of isolation available through Informix Dynamic Server and
set with the SET TRANSACTION statement in which a user can view only rows
that are currently committed at the moment of the query request; that is, a
user cannot view rows that were changed as a part of a currently uncommitted transaction. It is the default level of isolation under Dynamic Server for
databases that are not ANSI COMPLIANT. See isolation.
28
Informix Guide to SQL: Reference