database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-28 23:42:10 +03:00
Code Activity

Spell-check and markup police

Browse Source
This commit is contained in:
Peter Eisentraut
2002-01-20 22:19:57 +00:00
parent 75f0ba9fe3
commit bf43bed848
59 changed files with 748 additions and 749 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
doc/src/sgml/perform.sgml
View File

@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.15 2001/11/28 20:49:10 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.16 2002/01/20 22:19:56 petere Exp $
-->
<chapter id="performance-tips">
@ -403,7 +403,7 @@ regression=#
</para>
<table>
<title>pg_stats Columns</title>
<title><structname>pg_stats</structname> Columns</title>
<tgroup cols=3>
<thead>
@ -416,31 +416,31 @@ regression=#
<tbody>
<row>
<entry>tablename</entry>
<entry><literal>tablename</literal></entry>
<entry><type>name</type></entry>
<entry>Name of table containing column</entry>
</row>
<row>
<entry>attname</entry>
<entry><literal>attname</literal></entry>
<entry><type>name</type></entry>
<entry>Column described by this row</entry>
</row>
<row>
<entry>null_frac</entry>
<entry><literal>null_frac</literal></entry>
<entry><type>real</type></entry>
<entry>Fraction of column's entries that are NULL</entry>
</row>
<row>
<entry>avg_width</entry>
<entry><literal>avg_width</literal></entry>
<entry><type>integer</type></entry>
<entry>Average width in bytes of column's entries</entry>
</row>
<row>
<entry>n_distinct</entry>
<entry><literal>n_distinct</literal></entry>
<entry><type>real</type></entry>
<entry>If greater than zero, the estimated number of distinct values
in the column. If less than zero, the negative of the number of
@ -454,14 +454,14 @@ regression=#
</row>
<row>
<entry>most_common_vals</entry>
<entry><literal>most_common_vals</literal></entry>
<entry><type>text[]</type></entry>
<entry>A list of the most common values in the column. (Omitted if
no values seem to be more common than any others.)</entry>
</row>
<row>
<entry>most_common_freqs</entry>
<entry><literal>most_common_freqs</literal></entry>
<entry><type>real[]</type></entry>
<entry>A list of the frequencies of the most common values,
ie, number of occurrences of each divided by total number of rows.
@ -474,7 +474,7 @@ regression=#
<entry>A list of values that divide the column's values into
groups of approximately equal population. The
<structfield>most_common_vals</>, if present, are omitted from the
histogram calculation. (Omitted if column datatype does not have a
histogram calculation. (Omitted if column data type does not have a
<literal>&lt;</> operator, or if the <structfield>most_common_vals</>
list accounts for the entire population.)
</entry>
@ -485,9 +485,9 @@ regression=#
<entry><type>real</type></entry>
<entry>Statistical correlation between physical row ordering and
logical ordering of the column values. This ranges from -1 to +1.
When the value is near -1 or +1, an indexscan on the column will
When the value is near -1 or +1, an index scan on the column will
be estimated to be cheaper than when it is near zero, due to reduction
of random access to the disk. (Omitted if column datatype does
of random access to the disk. (Omitted if column data type does
not have a <literal>&lt;</> operator.)
</entry>
</row>