<p>MySQL raises ER_INDEX_CORRUPT (code 1712) when it detects a damaged index file that prevents reliable query execution.</p>
<p>MySQL Error 1712 (ER_INDEX_CORRUPT) means the server found a corrupted index on a table and has blocked access to avoid wrong results. Run CHECK TABLE, then rebuild or drop and recreate the damaged index with OPTIMIZE TABLE or ALTER TABLE to restore normal operation.</p>
Index %s is corrupted
MySQL throws Error 1712 with condition name ER_INDEX_CORRUPT when it finds that an index file associated with a table is damaged or out of sync with the underlying data. The server blocks operations that rely on the index until the corruption is fixed to prevent inaccurate query results or crashes.
The error can appear during SELECT, INSERT, UPDATE, or an ALTER TABLE command. It may also surface in replication when the replica reads a corrupted index on a relay table. Prompt repair avoids data loss and service disruption.
Hardware faults, abrupt server shutdowns, or full disks can leave index pages partially written, producing checksum mismatches that MySQL flags as corruption.
Using unsupported storage engines or mixing MySQL versions that handle index formats differently can create incompatibilities that MySQL treats as corruption.
Frequent ALTER TABLE or heavy concurrent writes without adequate buffer pool size increase the risk of index fragmentation and corruption, especially on older MyISAM tables.
First, back up the affected table with mysqldump or by copying the raw .ibd/.frm files while the server is offline. A backup preserves data if repair attempts fail.
Next, run CHECK TABLE your_table EXTENDED to confirm corruption scope. If the output recommends repair, execute either OPTIMIZE TABLE your_table or ALTER TABLE your_table ENGINE=InnoDB to rebuild all indexes.
If only one secondary index is corrupt, drop and recreate it: ALTER TABLE your_table DROP INDEX idx_name; ALTER TABLE your_table ADD INDEX idx_name(column_list); This rebuilds metadata without touching primary data pages.
Corruption detected on a MyISAM table: use REPAIR TABLE your_table QUICK or REPAIR TABLE your_table USE_FRM.
Replication stops with ER_INDEX_CORRUPT: stop replication, repair the table on the replica, then start replication with START SLAVE; ensure GTID consistency.
Clustered index corruption in InnoDB: export the table with mysqldump, drop it, recreate the schema, and reimport. This forces a fresh primary index build.
Store data on reliable SSDs protected by RAID 10 and battery-backed caching to minimize partial writes.
Always shut down MySQL with mysqladmin shutdown or systemctl stop mysqld to flush pages gracefully.
Enable innodb_checksum_algorithm=crc32 and innodb_flush_method=O_DIRECT to reduce corruption risk and detect issues early.
Schedule regular OPTIMIZE TABLE or pt-online-schema-change maintenance windows to keep indexes defragmented without blocking traffic.
Error 126 (HY000): Index file is crashed - similar corruption in MyISAM, fixed with REPAIR TABLE.
Error 1034 (HY000): Incorrect key file for table - often appears together, suggesting disk issues; resolve with REPAIR or ALTER.
Error 1577 (HY000): Cannot find index file - missing .ibd or .MYI file; restore from backup or rebuild table.
Power loss or full disk interrupts a write, leaving index pages partially updated and corrupted.
kill -9 on mysqld bypasses flush operations, producing inconsistent index metadata.
Bad sectors on HDDs or SSDs silently flip bits, damaging index checksum values.
Upgrading replicas before primaries can load tables with newer index formats that older servers misread as corruption.
Third party storage engine plugins that mishandle internal page structure can corrupt indexes under heavy load.
Occurs mainly on MyISAM tables and points to a damaged .MYI file; fix with REPAIR TABLE.
MySQL cannot open or read the key file, often due to corruption or permissions; opt for REPAIR or restore backup.
The index file is missing from disk; recreate the table or restore the lost .ibd/.MYI file from backup.
Spatial index corruption can trigger this error; rebuilding the spatial index usually resolves it.
No. REPAIR TABLE only applies to MyISAM. For InnoDB use OPTIMIZE TABLE or ALTER TABLE to rebuild indexes.
No. Indexes only accelerate queries. Dropping an index does not remove table rows.
Duration depends on table size and hardware. Expect temporary disk usage roughly equal to table size.
Galaxy encourages versioned, reviewed SQL and safe shutdown workflows, reducing risky ad-hoc schema changes that often lead to corruption.
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