SQL/MP Glossary

Glossary
Compaq NonStop™ SQL/MP Glossary—429832-001
Glossary-26
SCI (SQL compiler interface)
SCI (SQL compiler interface). .The NonStop SQL/MP interface to the host-language
compilers.
search condition. A predicate or compound predicate that defines the criteria for selecting
data or for including data in a table or view.
security string. The 4-character string of security codes that determines whether a user has
read, write, execute, or purge authority for an object.
select list. A list that specifies columns or expressions to include in the result of a query or
the columns in which to insert or update data.
selection. See projection
and restriction.
selectivity. A number, from 0 to 100, that denotes the estimated percentage of rows in a table
or an index that satisfy a search condition.
server. A process that receives, acts upon, and replies to messages from requesters. In
NonStop SQL/MP, a server can be a host language SQL application. Contrast with
requester
.
session. A particular execution of SQLCI from the time SQLCI is invoked to the time it is
terminated.
session attribute. One of a set of attributes consisting of environmental parameters,
DEFINEs, and options whose values describe the current session.
set operation. The ability to select and either update or delete a set of rows in a single SQL
operation.
set operator. A UNION or join operator.
shadow label. A file label that exists temporarily after an object has been dropped until the
transaction is committed or rolled back and the disk process removes the label, until
volume recovery is performed in the case of a node failure, or until file recovery is
performed in the case of a media failure.
shared lock. A lock exclusion mode that allows any number of processes to read the same
data but prevents any process from writing to the locked unit or reading it with intent to
rewrite. Contrast with exclusive lock
.
shorthand view. A view that can be derived from one or more tables or views by joining
tables or views, by projecting columns, by restricting rows, or by a combination of
these. A shorthand view can be read but not updated or secured. Contrast with protection
view.
similarity check. A check that the SQL executor and SQL compiler can make for an SQL
object in an execution plan to determine whether an invalid plan is operable. The
similarity check is faster than recompilation and reduces downtime for a program. See
also operable execution plan
and inoperable execution plan.