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oncheck reporting data pages more or less full than indicated in the bitmap

Troubleshooting


Problem

Starting with version 11.70.xC7W2 or 12.10.xC2 and with MAX_FILL_DATA_PAGES set to on, data pages of tables with variable row size potentially can hold more rows. On pre-existing data oncheck would report large numbers of inconsistencies between bitmap recorded and calculated mode (fullness). The release notes require a "repair" after migrating to such version.

Symptom

oncheck -cD on many tables reporting many errors of following type:

TBLspace data check for <db_name>:<owner>.<table_name>
WARNING: data page <page_num> in tablespace <partnum> appears to be
         more or less full than is indicated in the bitmap.
         Bitmap mode: 0xc, Calculated mode: 0x4.
WARNING: The bitmap mode for page <page_num> has been reset from 0xc to 0x4.

The second warning only appears when oncheck was ran with the -y auto-repair option.

Note that system catalog as well as user tables can be affected by this if they contain variable length (varchar, nvarchar, lvarchar) columns or if they are compressed.

[{"Product":{"code":"SSGU8G","label":"Informix Servers"},"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Component":"--","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF016","label":"Linux"},{"code":"PF022","label":"OS X"},{"code":"PF027","label":"Solaris"},{"code":"PF033","label":"Windows"}],"Version":"11.7;12.1","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

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Document Information

Modified date:
16 June 2018

UID

swg21675845

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