Relative performance question:
I have 2 UPDATE queires in a function.
table_a: 117,000 records
table_b: 117,000 records
table_c: 1.5 million records
#1 updates table_a, field_2 from table_b, field_1 based on a joining field_3.
Around 110,000 updates
#2 updates table_a, field_5 from table_c, field_2 joining on field_3.
Around 110,000 updates.
#1 takes 5-7 minutes; #2 takes about 15 seconds. The only difference I can
discern is that table_a, field_2 is indexed and table_a, field_5 is not.
Is it reasonable that updating the index would actually make the query take
20x longer? If not, I'll post actual table defs and query statements.
--
Josh Berkus
josh@agliodbs.com
Aglio Database Solutions
San Francisco