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Postgres FD Implementation
Commit d12be5c3 authored by Bruce Momjian's avatar Bruce Momjian
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Add section on testing index scan.

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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sun Jan 12 13:36:11 EST 2003 Last updated: Fri Jan 17 12:15:04 EST 2003
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
...@@ -749,6 +749,10 @@ ...@@ -749,6 +749,10 @@
ORDER BY col [ DESC ] ORDER BY col [ DESC ]
LIMIT 1; LIMIT 1;
If you believe the optimizer is incorrect in choosing a sequential
scan, use SET enable_seqscan TO 'off' and run tests to see if an index
scan is indeed faster.
When using wild-card operators such as LIKE or ~, indexes can only be When using wild-card operators such as LIKE or ~, indexes can only be
used in certain circumstances: used in certain circumstances:
* The beginning of the search string must be anchored to the start * The beginning of the search string must be anchored to the start
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