SQL Query Issues

Q: JDBC Connection Failure Error

When executing queries, users may encounter the following error:

[HY000][1105] Can not connect to jdbc due to error: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Recommended troubleshooting steps:

1. Add autoReconnect=true parameter to the JDBC URL and set wait_timeout to 24 hours for observation
2. For catalog-related issues, verify MySQL connection details and driver version compatibility
3. Enable testOnBorrow configuration for connection validation

Q: Empty Missed Versions Error

Error message: [E-230]missed_versions is empty

Solution: Increase the tablet_rowset_stale_sweep_time_sec parameter in BE configuration and restart the BE node. This parameter extends the retention period for merged versions, preventing necessary versions from being cleaned up during frequent write operations.

Data Operations

Q: Timezone Handling in Doris

Doris uses the server's timezone configuration (default UTC+8). For timestamp storage:

• Use BIGINT type for Unix timestamp storage
• DATETIME type is available for date-time values
• Native timestamp type support was added in Release 2.1

Q: Partition and Bucket Modifications

Changing partition or bucket configuration for existing tables:

• Historical data remains unaffected by bucket count changes
• New partitions will use the updated bucket configuration
• Partition and bucket fields cannot be modified after table creation
• Structural changes require table recreation and data migration

Q: Stream Load Profile Information

To access profile information for Stream Load operations:

curl -H "enable_profile: true" -X PUT http://host:port/api/db/table/_stream_load

When enabled, profile data is logged to be.INFO for performance analysis.

Q: Data Insertion Result Mismatch

When insetred data count doesn't match expectations:

• Check for duplicate key aggregation in target table
• Verify strict mode setting: SET enable_insert_strict = true;
• Test with temporary table creation: CREATE TABLE temp_table AS SELECT ...

System Maintenance

Q: Disk Failure Recovery

Handling BE node disk failures:

# For multi-replica clusters (≥2 replicas, 2 BEs):
1. Remove failed disk from system
2. Update BE configuration to exclude failed storage path
3. Restart BE node - automatic data repair will occur

# For single-replica clusters:
1. Remove failed disk
2. Identify affected tables and recreate with data refresh

Production environments should maintain ≥3 replicas across 3 BE nodes for high availability.

Q: Windows Platform Support

Apache Doris does not currently support Windows systems. Use virtualization or WSL2 for development and testing on Windows platforms.

Development and Compilation

Q: Maven Plugin Dependency Error

Compilation error: Failed to parse plugin descriptor for net.sourceforge.czt.dev:cup-maven-plugin:1.6-cdh

Solutions:

1. Temporarily change Maven mirror to Cloudera repository: ``` cloudera-mirror <mirrorOf>central</mirrorOf> Cloudera Repository https://repository.cloudera.com/repository/libs-release-local/

2. Manually download required JAR files from Cloudera repository and place in local Maven repository