Skip to main content

analyze_histogram

  • June 20, 2017
  • 3 replies
  • 19 views

sreeblr
Forum|alt.badge.img+2

After loading a table with significant volume >50 % the recommendation as per vertica manuals is to run analyze_statistics which take 10 pct sample. Is this enough or should we run analyze_histogram. What should be ideal sample percent (1-100) ? Also does vertica automatically run analyze_statistics after purge /delete or on any other trigger?

3 replies

sreeblr
Forum|alt.badge.img+2
  • Author
  • Participating Frequently
  • June 20, 2017

when running analyze_histogram on table with millions of rows getting error "Analyze Statistics operation is already in progress on projection" .Did vertica trigger analyze_statistics after the table was purged which caused issue when we executed analyze_histogram ?


TomM
Forum|alt.badge.img
  • Participating Frequently
  • June 20, 2017

Pretty sure the only way analyze_statistics gets run is if YOU run it. Not sure what that message you're getting is.


Moshe
Forum|alt.badge.img
  • Participating Frequently
  • June 21, 2017

ANALYZE_STATISTICS is an alias of the function ANALYZE_HISTOGRAM, which is no longer documented.
Some customers use daily partition, because they don't delete data to avoid delete vectors. They do ETL work in staging and then swap partition.
Analyze_histogram might take long time to complete if there are many columns and many partitions. Analyze stats runs faster on fewer partitions because of fewer files, fewer FS interactions etc. (See Jira VER-54532)