Checking R-Tree Indexes with the oncheck Utility

The oncheck utility is a database server utility that checks and displays information about database server disk structures. You can use all the default options of the oncheck utility to check R-tree indexes.

For R-tree indexes, you can use the default oncheck options to check that the bounding boxes for each item on a given page are contained in the master bounding box for the page. You can also check for possible incomplete splits, which can be detected by the oncheck utility by comparing some internal information between pages. You can also use the oncheck utility to check that the bounding box of a parent entry on a given page matches the bounding box of the child page. Finally, you can check that all leaf pages that have a right sibling contain a right-pointing link that points to the correct leaf page.

When you check an R-tree index with the default options of the oncheck utility, the database server takes a shared lock on the index fragment currently being checked.

The following oncheck options check and display information for an R-tree index.

Option

Purpose

-ci, -cI

Performs standard index checking with minimal output

Both options display the same output.

-pT

Performs some index checking and displays only index summary information

-pk, -pK

Performs index checking of each page in the index

Primarily displays internal page information about the root and branch pages, although it also displays minimal information about the leaf pages.

Both options display the same output.

-pl, -pL

Similar to -pk and -pK except that it displays additional information about leaf pages

Both options display the same output.

-u parameter

Depending on the parameter you specify, restricts the checking of an R-tree index to specified levels and pages or performs a cleanup of an R-tree index

This option applies to R-tree indexes only. You cannot use this option to check other types of indexes.

For information about the exact syntax of oncheck options, refer to the IBM Informix: Administrator's Guide for your database server.