How to deal with oracle index failure

Index failure will lead to a degradation in query performance, mainly because data updates do not update the index in time. The columns on the index change. The index is marked as unavailable. Index statistics are outdated. Index syntax error. Other factors (such as tablespace corruption or DB instance failure).

Oracle Index Failure Handling

When Oracle index fails, query performance will drop significantly. The main reasons are as follows:

1. Data update does not update the index in time

When the data in the data table is updated, the corresponding index is not updated in time, resulting in inconsistent with the data table, and the index cannot be used during query.

Handling: Use the DDL command to rebuild the index to force Oracle to update the index.

 <code class="sql">ALTER INDEX index_name REBUILD;</code>

2. The columns on the index change

If the column data type or length on the index changes, the index will be invalid.

Processing method: Reconstruct the index to reflect the changes in the column.

 <code class="sql">ALTER INDEX index_name REBUILD;</code>

3. The index is marked as unavailable

If the index is explicitly marked as unavailable after creation or modification, the index will not be used during querying.

How to handle: Use the ALTER INDEX command to enable indexing.

 <code class="sql">ALTER INDEX index_name ENABLE;</code>

4. Index statistics are outdated

Over time, index statistics can become obsolete, causing the optimizer to make incorrect decisions.

Processing: Use the ANALYZE command to update index statistics.

 <code class="sql">ANALYZE TABLE table_name COMPUTE STATISTICS;</code>

5. Index syntax error

If there is a syntax error in the creation statement of the index, the index will be invalid.

Processing method: Check and fix the index creation statement.

 <code class="sql">CREATE INDEX index_name ON table_name (column_name);</code>

6. Other reasons

In some cases, index failure can be caused by other factors, such as tablespace corruption or database instance failure.

How to deal with it: Troubleshoot a situation-specific situation, such as repairing a damaged tablespace or restarting a database instance.

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