Re: Most-common value docs in PG 12
Bruce Momjian <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.devel.documentation |
|---|---|
| Message-ID | <[email protected]> |
On Wed, Aug 28, 2019 at 08:25:41PM +0200, Tomas Vondra wrote: > On Wed, Aug 28, 2019 at 12:22:38PM -0400, Bruce Momjian wrote: > > If this is so, why don't we show the CREATE STATISTICS example as > > city/state, and not state/city? > > Yes, we deduplicate the attributes and store them sorted by attnum. I'm > not sure it makes sense to change the example to match this order, which > is mostly an implementation detail, though. It might be better to point > out the order may not exactly match CREATE STATISTICS, and point users to > what e.g. "\d" shows (because that will show the order as stored in the > system catalog). OK, how is this patch? I didn't mention psql since I think everyone expects psql to show all information about tables and indexes. -- Bruce Momjian <[email protected]> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
mcv.diff
(text/x-diff, 1.8 KB)
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 8e165832b3..a645127e69 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -1172,7 +1172,7 @@ WHERE tablename = 'road';
<para>
Here is an example of collecting functional-dependency statistics:
<programlisting>
-CREATE STATISTICS stts (dependencies) ON zip, city FROM zipcodes;
+CREATE STATISTICS stts (dependencies) ON city, zip FROM zipcodes;
ANALYZE zipcodes;
@@ -1262,7 +1262,7 @@ SELECT * FROM zipcodes WHERE city = 'San Francisco' AND zip = '90210';
Continuing the previous example, the n-distinct counts in a
table of ZIP codes might look like the following:
<programlisting>
-CREATE STATISTICS stts2 (ndistinct) ON zip, state, city FROM zipcodes;
+CREATE STATISTICS stts2 (ndistinct) ON city, state, zip FROM zipcodes;
ANALYZE zipcodes;
@@ -1317,7 +1317,7 @@ nd | {"1, 2": 33178, "1, 5": 33178, "2, 5": 27435, "1, 2, 5": 33178}
a function is required for inspection of MCV contents):
<programlisting>
-CREATE STATISTICS stts3 (mcv) ON state, city FROM zipcodes;
+CREATE STATISTICS stts3 (mcv) ON city, state FROM zipcodes;
ANALYZE zipcodes;
diff --git a/doc/src/sgml/ref/create_statistics.sgml b/doc/src/sgml/ref/create_statistics.sgml
index ec23a154d6..5b583aacb4 100644
--- a/doc/src/sgml/ref/create_statistics.sgml
+++ b/doc/src/sgml/ref/create_statistics.sgml
@@ -98,7 +98,8 @@ CREATE STATISTICS [ IF NOT EXISTS ] <replaceable class="parameter">statistics_na
<listitem>
<para>
The name of a table column to be covered by the computed statistics.
- At least two column names must be given.
+ At least two column names must be given; the order of the column names
+ is insignificant.
</para>
</listitem>
</varlistentry>