Analyze_histogram and statistics in Vertica 6.1
Hi there, I just had some questions on how vertica generates statistics. I was under the impression Vertica automatically does not do this, and I would need to run analyze_histogram manually after a big load/partition drop, etc. But when I was looking at the system table v_monitor.projection_columns, I see the column "statistics_updated_timestamp" being updated. And I don't think it's any of the processes we have in-place but Vertica itself doing it. Am I wrong on this? Is Vertica updating statistics after a load or something? Or I misinterpreting the information somehow (or confusing myself). Also - I had a question on the usage of ANALYZE_HISTOGRAM if I do SELECT ANALYZE_HISTOGRAM('table_name',100) -- will it analyze statistics on each individual column by reading 100% of the data (or whatever row limit there is). What is the performance difference between analyzing histogram on table level, instead of of running analyze_histogram on each column in a table? Hope to hear from somebody! Thanks in advance.