<p>MySQL throws ER_NEED_REPREPARE when a prepared statement becomes invalid after underlying table metadata changes.</p>
<p>MySQL Error 1615: ER_NEED_REPREPARE occurs when a prepared statement is executed after its referenced table has changed. Reprepare the statement, flush the statement cache, or increase table_definition_cache to resolve the issue.</p>
Prepared statement needs to be re-prepared
MySQL raises ER_NEED_REPREPARE with SQLSTATE HY000 when it detects that a prepared statement references metadata that has changed since the statement was compiled. The server invalidates the cached execution plan and forces the client to prepare the statement again before it can run.
The error usually surfaces in long-running applications, connection pools, or stored procedures that reuse prepared statements. It signals that the database schema was altered, a table was recreated, or internal caches were purged.
Table definition changes such as ALTER TABLE, DROP INDEX, or column type modifications invalidate existing prepared statements. MySQL demands a fresh prepare phase to rebuild an accurate execution plan.
Insufficient table_definition_cache or table_open_cache settings can trigger automatic eviction of cached metadata. When the statement tries to use an evicted definition, ER_NEED_REPREPARE fires.
In replication or clustered setups, metadata divergence between servers may force reprepare events during failover or read-after-write routing.
Client-side fix: catch the error, close the old prepared statement, and issue a new PREPARE. Most MySQL connectors expose a reconnect or auto-reprepare option.
Server-side fix: boost table_definition_cache and table_open_cache so table metadata remains resident. This lowers the chance of eviction and reprepare requirements.
Operational fix: schedule schema migrations during maintenance windows and restart applications so new prepares occur cleanly.
High-throughput web services often reuse pooled connections. Add error handling that retries the query after repreparing to maintain uptime.
Stored procedures that call PREPARE inside loops may fail after a DDL change. Refresh the procedure or drop and recreate it to incorporate the new schema.
Adopt strict versioned migrations to minimize hot schema changes. Coordinate DDL with application restarts to avoid stale prepares.
Monitor Prepared_stmt_count and Open_table_definitions metrics. If counts approach cache limits, raise the corresponding variables before saturation leads to reprepare events.
Using Galaxy, developers can version SQL in Collections, ensuring teammates reuse updated queries after schema changes, reducing ER_NEED_REPREPARE incidents.
ALTER TABLE, ADD/DROP INDEX, or column modifications invalidate cached metadata.
Low table_definition_cache forces MySQL to purge definitions, breaking prepared statements.
Recreating a table assigns a new object ID, making previous prepares unusable.
Metadata mismatch across nodes forces statements to reprepare when routing shifts.
Occurs during transaction conflicts - unrelated to metadata but often surfaces with high concurrency.
Thrown when a query references a missing table, sometimes after incorrect schema changes.
Network or timeout issues can drop pooled connections, leading to stale prepared statements.
No. The error only concerns statement metadata. Your data remains intact.
It reduces frequency but cannot eliminate errors caused by intentional schema changes.
Galaxy versions queries, highlights schema diffs, and encourages revalidation, lowering the risk of stale prepared statements.
Usually not. Repreparing statements or flushing caches fixes the issue without a server restart.
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