"Nick Fankhauser" <[EMAIL PROTECTED]> writes: > This indicates to me that 1 isn't too shabby as an estimate if the whole > name is specified, but I'm not sure how this gets altered in the case of a > "LIKE"
For a pattern like "SANDERS%", the estimate is basically a range estimate for this condition: > ((actor_full_name_uppercase >= 'SANDERS'::character varying) AND > (actor_full_name_uppercase < 'SANDERT'::character varying)) > n_distinct | -0.14701 > Question: What does it mean when n_distinct is negative? It means that the number of distinct values is estimated as a fraction of the table size, rather than an absolute number. In this case 14.7% of the table size, which is a bit off compared to the correct value of 43% (1453371/3386359), but at least it's of the right order of magnitude now ... > -> Index Scan using > actor_full_name_uppercase on actor (cost=0.00..456.88 rows=113 width=42) > (actual time=32.80..3197.28 rows=3501 loops=1) Hmm. Better, but not enough better to force a different plan choice. You might have to resort to brute force, like "set enable_nestloop=false". Just out of curiosity, what do you get if you do that? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])