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From: Josh Kupershmidt <[email protected]>
To: pgsql-docs <[email protected]>
Subject: Outdated note about unique indexes
Date: Wed, 8 Jul 2015 17:56:09 -0400
Message-ID: <CAK3UJRE4wGWMjGOfUZcTAOn_k43ETi-jh6FsLF7XX3=Qmkdt3A@mail.gmail.com> (raw)
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Hi,

I noticed that the note on a page about unique indexes

http://www.postgresql.org/docs/current/static/indexes-unique.html

says "The preferred way to add a unique constraint to a table is ALTER
TABLE ... ADD CONSTRAINT. The use of indexes to enforce unique constraints
could be considered an implementation detail that should not be accessed
directly... ".

That note has been there forever, in particular since before we supported
CONCURRENTLY, which is pretty darn important in many uses nowadays. Since
it seems like some users have taken this suggestion seriously, e.g. on
stackoverflow[1], how about we remove this outdated suggestion? There is
already a previous mention a few sections earlier[2] suggesting the use of
CONCURRENTLY, so I don't think we really need to reiterate that suggestion
here.

Josh

[1]
http://stackoverflow.com/questions/23542794/postgres-unique-constraint-vs-index
[2] http://www.postgresql.org/docs/current/interactive/indexes-intro.html

diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml
index 309fd12..2d131c9 100644
--- a/doc/src/sgml/indices.sgml
+++ b/doc/src/sgml/indices.sgml
@@ -655,11 +655,7 @@ CREATE UNIQUE INDEX <replaceable>name</replaceable> ON <replaceable>table</repla
 
   <note>
    <para>
-    The preferred way to add a unique constraint to a table is
-    <literal>ALTER TABLE ... ADD CONSTRAINT</literal>.  The use of
-    indexes to enforce unique constraints could be considered an
-    implementation detail that should not be accessed directly.
-    One should, however, be aware that there's no need to manually
+    There's no need to manually
     create indexes on unique columns; doing so would just duplicate
     the automatically-created index.
    </para>


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Attachments:

  [text/plain] indices_constraint_suggestion.diff (769B, 3-indices_constraint_suggestion.diff)
  download | inline diff:
diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml
index 309fd12..2d131c9 100644
--- a/doc/src/sgml/indices.sgml
+++ b/doc/src/sgml/indices.sgml
@@ -655,11 +655,7 @@ CREATE UNIQUE INDEX <replaceable>name</replaceable> ON <replaceable>table</repla
 
   <note>
    <para>
-    The preferred way to add a unique constraint to a table is
-    <literal>ALTER TABLE ... ADD CONSTRAINT</literal>.  The use of
-    indexes to enforce unique constraints could be considered an
-    implementation detail that should not be accessed directly.
-    One should, however, be aware that there's no need to manually
+    There's no need to manually
     create indexes on unique columns; doing so would just duplicate
     the automatically-created index.
    </para>

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