IBM 000-8697 Uživatelský manuál stáhnout pdf (Strana 130)

100

101

2-36 IBM Informix OnLine Database Server Administrator’s Guide

Shared Memory and Process Communication

Shared memory refers to the use of the same memory segments by more than

one OnLine user process, enabling interprocess communication. Figure 2-4

onpage 2-37showshowmultipleuserprocessescancommunicatebywayof

shared memory.

Interprocess communication via shared memory has the following advan-

tagesoversystemsinwhichserverprocesseseachmaintaintheirownprivate

copy of data:

■ Disk I/O is reduced because buffers, which are managed as a

common pool, are ﬂushed on a system-wide basis instead of a per-

process basis.

■ Execution time is reduced because only one copy of a data or index

page is maintained in shared memory. Processes do not need to

reread shared-memory buffers to ensure that their data is current.

Often, processes do not need to read a page in from disk if the page

is already in shared memory as a result of an earlier query.

1 2 ... 125 126 127 128 129 130 131 132 133 134 135 ... 701 702

Komentáře k této Příručce

Žádné komentáře

IBM 000-8697 Uživatelský manuál Strana 130

Komentáře k této Příručce

Související produkty a manuály pro Databázový software IBM 000-8697