Error
Error Code:
692
SAP S/4HANA Error 692: Deprecated SQL Plan Stability
Description
This error indicates that the system is attempting to use a deprecated SQL plan stability feature, but the corresponding stored plan table is empty. It typically occurs after system upgrades or migrations where older plan stability mechanisms are no longer supported or configured.
Error Message
ERR_SQL_PLAN_STABILITY_TABLE_EMPTY_DEPRECATED
Known Causes
4 known causesDeprecated Feature Usage
The system is attempting to utilize an SQL plan stability feature that has been deprecated in the current SAP S/4HANA version.
Incomplete Upgrade or Migration
During an upgrade or migration, older plan stability configurations or tables might not have been properly removed or transitioned to new mechanisms.
Missing or Empty Plan Table
Even if the feature were supported, the specific table intended to store stable SQL plans is found to be empty, preventing its use.
Incorrect System Configuration
The current system configuration might still refer to or attempt to invoke deprecated plan stability features, leading to this error.
Solutions
3 solutions available1. Re-enable SQL Plan Stability easy
Temporarily re-enable SQL Plan Stability to allow the system to generate new plans.
1
Access the SAP HANA Studio or SAP HANA Cockpit.
2
Navigate to the SQL Plan Stability configuration. This is typically found under the System Configuration or Administration section.
3
Locate the setting for SQL Plan Stability and enable it. The specific parameter might be related to 'SQL_PLAN_STABILITY' or 'PLAN_STABILITY'.
4
Apply the changes and restart the SAP HANA database instance.
5
After the restart, allow the system to generate new SQL plans. This may involve running typical application transactions. Monitor the system for a period.
6
Once the error subsides and new plans are generated, you can consider disabling SQL Plan Stability again if it was previously disabled for performance reasons, or leave it enabled if it's a strategic decision.
2. Clear and Regenerate SQL Plan Cache medium
Manually clear the SQL plan cache and allow it to rebuild.
1
Connect to the SAP HANA database using a user with sufficient privileges (e.g., SYSTEM).
2
Execute the following SQL statement to clear the SQL plan cache. This will force the database to re-evaluate and generate plans for previously executed statements.
ALTER SYSTEM CLEAR SQL PLAN CACHE;3
Wait for the cache to be cleared. This operation is typically fast.
4
Run typical application transactions or specific queries that are known to trigger this error. This will prompt the database to generate new SQL plans for these statements.
5
Monitor the system for the recurrence of Error 692. If the error is resolved, the cache has been successfully regenerated.
3. Review and Optimize Problematic SQL Statements advanced
Identify and optimize the SQL statements causing the empty plan stability table.
1
Identify the SQL statements associated with Error 692. This might require analyzing system logs, tracing tools (like SQL Trace or XS Advanced Traces), or using SAP HANA's performance monitoring views.
2
Use SAP HANA's explain plan functionality to analyze the execution plan of these identified SQL statements.
EXPLAIN <your_sql_statement>;3
Look for potential performance bottlenecks, inefficient joins, missing indexes, or outdated statistics within the explain plan.
4
Consider rewriting the SQL statements for better performance. This might involve:
- Using more specific `WHERE` clauses.
- Optimizing join conditions.
- Avoiding `SELECT *`.
- Using appropriate table functions or procedures.
- Ensuring statistics are up-to-date.
- Using more specific `WHERE` clauses.
- Optimizing join conditions.
- Avoiding `SELECT *`.
- Using appropriate table functions or procedures.
- Ensuring statistics are up-to-date.
5
After optimizing the SQL statements, re-execute them and monitor if the SQL Plan Stability table is populated correctly for these statements. This might require clearing the cache and re-enabling stability temporarily as a testing step.