Is it ok to Run ANALYZE TABLE COMPUTE DELTA STATISTICS While data is loading into a Delta Table?

[Sainath368]

Hi all,

I have a doubt regarding the best practices for running  ANALYZE TABLE table_name COMPUTE DELTA STATISTICS on a Delta table. Is it recommended to execute this command while data is being loaded into the table, or should it be run afterward? Additionally, does running this command during an active data load create any performance issues? I’m looking for insights on the optimal timing and its impact on query performance, data skipping efficiency, and potential resource contention. Any guidance would be greatly appreciated!

[nikhilj0421]

ANALYZE TABLE is a read-only operation. It reads the data to compute statistics but does not modify the data. Running ANALYZE TABLE COMPUTE DELTA STATISTICS while data is still being loaded into a Delta table is generally not recommended. The ANALYZE TABLE command is designed to gather statistics from the Delta log for optimized query performance, but doing this during ongoing data writes could lead to inconsistencies in the collected statistics.

Query Performance	- Statistics updates improve query planning accuracy for future queries. - Outdated statistics may lead to suboptimal query plans until ANALYZE completes.
Resource Contention	- Concurrent ANALYZE and writes compete for cluster resources (CPU, I/O, memory). - Heavy write workloads may experience latency spikes if ANALYZE scans large datasets.
Data Skipping Efficiency	- Statistics reflect data up to the snapshot when ANALYZE starts. - Newly loaded data remains unindexed until the next ANALYZE run.

[nayan_wylde]

It is recommended to run ANALYZE TABLE table_name COMPUTE DELTA STATISTICS after the data has been loaded into the Delta table, rather than while the data is being loaded.

1. Data consistency: Running the command after the data has been loaded ensures that the statistics are collected on a consistent view of the data, which is essential for accurate query optimization.
2. Statistics accuracy: If the command is run while the data is being loaded, the statistics may not reflect the final state of the data, which can lead to suboptimal query plans.
3. Performance: Running the command after the data has been loaded allows the statistics collection process to run without interfering with the data loading process, which can improve overall performance.