|
|
|
@ -1,7 +1,7 @@ |
|
|
|
|
|
|
|
|
|
Frequently Asked Questions (FAQ) for PostgreSQL |
|
|
|
|
|
|
|
|
|
Last updated: Sun Jun 23 17:16:13 EDT 2002 |
|
|
|
|
Last updated: Mon Jun 24 21:45:50 EDT 2002 |
|
|
|
|
|
|
|
|
|
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) |
|
|
|
|
|
|
|
|
@ -743,13 +743,14 @@ |
|
|
|
|
using an index with ORDER BY and LIMIT: |
|
|
|
|
SELECT col |
|
|
|
|
FROM tab |
|
|
|
|
ORDER BY col |
|
|
|
|
ORDER BY col [ DESC ] |
|
|
|
|
LIMIT 1 |
|
|
|
|
|
|
|
|
|
When using wild-card operators such as LIKE or ~, indexes can only be |
|
|
|
|
used if the beginning of the search is anchored to the start of the |
|
|
|
|
string. Therefore, to use indexes, LIKE patterns must not start with |
|
|
|
|
%, and ~(regular expression) patterns must start with ^. |
|
|
|
|
used if the default C local is used during initdb and the beginning of |
|
|
|
|
the search is anchored to the start of the string. Therefore, to use |
|
|
|
|
indexes, LIKE patterns must not start with %, and ~(regular |
|
|
|
|
expression) patterns must start with ^. |
|
|
|
|
|
|
|
|
|
4.9) How do I see how the query optimizer is evaluating my query? |
|
|
|
|
|
|
|
|
|