The issue you're facing is that the Dameng database optimizer chooses different execution plans for the same query in your development and production environments, even though the database version and indexes are identical. Here's a breakdown of the situation and some troubleshooting steps:

Problem: Different execution plans in development and production environments

Possible Causes:

Statistics: Outdated or inaccurate statistics on the tables involved in your query can lead the optimizer to make poor decisions about which indexes to use. Data distribution: If the data distribution is significantly different between development and production environments, the optimizer might choose different access methods. Other configuration settings: There might be subtle differences in configuration settings between environments that affect the optimizer's behaviour.

The issue you're facing is that the Dameng database optimizer is choosing different execution plans for the same query in your development and production environments, even though the database version and indexes are identical. Here's a breakdown of the situation and some troubleshooting steps:

Problem: Different execution plans in development and production environments

Possible Causes:

Statistics: Outdated or inaccurate statistics on the tables involved in your query can lead the optimizer to make poor decisions about which indexes to use. Data distribution: If the data distribution is significantly different between development and production environments, the optimizer might choose different access methods. Other configuration settings: There might be subtle differences in configuration settings between environments that affect the optimizer's behavior.

Troubleshooting Steps:

1. Check Statistics:

Use the EXPLAIN command with the FOR STATISTICS option to see the statistics used by the optimizer.

If the statistics seem outdated (e.g., don't reflect the current data distribution), gather new statistics using ANALYZE or similar commands.

2. Analyze Data Distribution:

Check if the data volume and value distribution are similar in both environments. Significant differences can impact the optimizer's choice.

3. Review Configuration Differences:

Compare configuration settings related to the optimizer and indexing in both environments. Look for subtle differences that might affect behavior.

4.Force Index Usage (Optional):

As a last resort, you can try forcing the use of the desired index with hints in your SQL statement. This is not ideal as it bypasses the optimizer, but it can be helpful for testing purposes.