I have 2 tables with a 200,000 rows of data 3 character/string columns ID,
Question and Response. The query below compares the data between the 2 tables
based on ID and Question and if the Response does not match between the left
table and the right table it identifies the ID's where there is a mismatch.
Running the query in SQL Server 2008 using the ISNULL function take a few
milliseconds. Running the same query in Postgresql takes over 70 seconds. The 2
queries are below:
SQL Server 2008 R2 Queryselect t1.id from table1 t1 inner join table2 t2 on
t1.id = t2.id and t1.question = t2.question and isnull(t1.response,'ISNULL') <>
isnull(t2.response,'ISNULL')
Postgres 9.1 Queryselect t1.id from table1 t1 inner join table2 t2 on t1.id =
t2.id and t1.question = t2.question and coalesce(t1.response,'ISNULL') <>
coalesce(t2.response,'ISNULL')
What gives?
