IBM 000-8697 Bedienungsanleitung PDF herunterladen (Seite 436)

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4-64 IBM Informix OnLine Database Server Administrator’s Guide

Using tbunload and tbload

tbunload

The tbunload utility can unload data more quickly than either dbexport or

theUNLOADcommandbecauseitcopiesthedatainbinaryandinpage-sized

units. However, this places some constraints on its use:

■ tbunload writes data to tape only.

■ Youmustloadthetape written by tbunload onto a machinewiththe

same page size as the original machine.

■ You must loadthedataon thetbunload tape intoadatabase or table

managed by OnLine.

■ When you unload a complete database, ownership of all database

objects (suchas tables,indexes, andviews) cannotbe modiﬁed until

after the database is unloaded.

■ tbunload unloads page images. If you load the pages to another

machinethatstoresnumericdatatypesdifferentlythanyourcurrent

machine (for example, with the most signiﬁcant byte last instead of

ﬁrst), the contents of the data page could be misinterpreted.

■ tbunload does not carry over access privileges or synonyms that

were deﬁned on the original tables.

tbload

The tbload utility performs faster than the dbimport, dbload, or LOAD

options. In exchange for this higher performance, the following ﬁve

constraints exist:

■ tbload can only create a new database or table; you must drop or

renameanexistingdatabaseor table of thesamenamebeforetbload

is run. (tbloadpromptsyou to rename blobspaces duringexecution,

if desired.)

■ tbload locks the database or table exclusively during the load.

■ When you load a complete database, the user executing tbload

becomes the owner of the database.

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