Here are two new FAQ items. They are on the web site, along with an
expanded TODO list.
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4.22) How do I create a column that will default to the current time?
The tempation is to do:
create table test (x int, modtime timestamp default 'now');
but this makes the column default to the time of table creation, not the
time of row insertion.
Instead do:
CREATE TABLE test (x int, modtime timestamp default now() );
The calling of the function now() prevents the default value from being
computed at table creation time, and delays it until insertion time. We
believe this will not be a problem in post-6.5.* releases.
4.23) Why are my subqueries using IN so slow?
Currently, we join subqueries to outer queries by sequential scanning
the result of the subquery for each row of the outer query. A workaround
is to replace IN with EXISTS. For example, change:
SELECT *
FROM tab
WHERE col1 IN (SELECT col2 FROM TAB2)
to:
SELECT *
FROM tab
WHERE EXISTS (SELECT col2 FROM TAB2 WHERE col1 = col2)
We hope to fix this limitation in a future release.
--
Bruce Momjian | http://www.op.net/~candle
maillist@candle.pha.pa.us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
