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Commit 0ff4352

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peterepetere
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Add some real descriptions to the multiargument aggregate functions rather
than just showing the incomprehensible formulas.
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‎doc/src/sgml/func.sgml

Lines changed: 33 additions & 65 deletions
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@@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.344 2006/10/23 18:10:31 petere Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.345 2006/10/23 19:57:37 petere Exp $ -->
22

33
<chapter id="functions">
44
<title>Functions and Operators</title>
@@ -8102,17 +8102,7 @@ SELECT count(*) FROM sometable;
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<entry>
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<type>double precision</type>
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</entry>
8105-
<entry>sqrt((<replaceable class="parameter">N</replaceable> *
8106-
sum(<replaceable class="parameter">X</replaceable>*<replaceable
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class="parameter">Y</replaceable>) - sum(<replaceable
8108-
class="parameter">X</replaceable>) * sum(<replaceable
8109-
class="parameter">Y</replaceable>))^2 / ((<replaceable
8110-
class="parameter">N</replaceable> * sum(<replaceable
8111-
class="parameter">X</replaceable>^2) - sum(<replaceable
8112-
class="parameter">X</replaceable>)^2) * (<replaceable
8113-
class="parameter">N</replaceable> * sum(<replaceable
8114-
class="parameter">Y</replaceable>^2) - sum(<replaceable
8115-
class="parameter">Y</replaceable>)^2)))</entry>
8105+
<entry>correlation coefficient</entry>
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</row>
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81188108
<row>
@@ -8129,12 +8119,7 @@ SELECT count(*) FROM sometable;
81298119
<entry>
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<type>double precision</type>
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</entry>
8132-
<entry>(sum(<replaceable class="parameter">X</replaceable>*<replaceable
8133-
class="parameter">Y</replaceable>) - sum(<replaceable
8134-
class="parameter">X</replaceable>) * sum(<replaceable
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class="parameter">Y</replaceable>) / <replaceable
8136-
class="parameter">N</replaceable>) / <replaceable
8137-
class="parameter">N</replaceable></entry>
8122+
<entry>population covariance</entry>
81388123
</row>
81398124

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<row>
@@ -8151,12 +8136,7 @@ SELECT count(*) FROM sometable;
81518136
<entry>
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<type>double precision</type>
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</entry>
8154-
<entry>(sum(<replaceable class="parameter">X</replaceable>*<replaceable
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class="parameter">Y</replaceable>) - sum(<replaceable
8156-
class="parameter">X</replaceable>) * sum(<replaceable
8157-
class="parameter">Y</replaceable>) / <replaceable
8158-
class="parameter">N</replaceable>) / (<replaceable
8159-
class="parameter">N</replaceable> - 1)</entry>
8139+
<entry>sample covariance</entry>
81608140
</row>
81618141

81628142
<row>
@@ -8169,8 +8149,8 @@ SELECT count(*) FROM sometable;
81698149
<entry>
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<type>double precision</type>
81718151
</entry>
8172-
<entry>sum(<replaceable class="parameter">X</replaceable>) /
8173-
<replaceable class="parameter">N</replaceable></entry>
8152+
<entry>average of the independent variable
8153+
(<literal>sum(<replaceable class="parameter">X</replaceable>)/<replaceable class="parameter">N</replaceable></literal>)</entry>
81748154
</row>
81758155

81768156
<row>
@@ -8183,8 +8163,8 @@ SELECT count(*) FROM sometable;
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<entry>
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<type>double precision</type>
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</entry>
8186-
<entry>sum(<replaceable class="parameter">Y</replaceable>) /
8187-
<replaceable class="parameter">N</replaceable></entry>
8166+
<entry>average of the dependent variable
8167+
(<literal>sum(<replaceable class="parameter">Y</replaceable>)/<replaceable class="parameter">N</replaceable></literal>)</entry>
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</row>
81898169

81908170
<row>
@@ -8197,7 +8177,7 @@ SELECT count(*) FROM sometable;
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<entry>
81988178
<type>bigint</type>
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</entry>
8200-
<entry>number of input rows in which both expressions are non-null</entry>
8180+
<entry>number of input rows in which both expressions are nonnull</entry>
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</row>
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<row>
@@ -8213,14 +8193,10 @@ SELECT count(*) FROM sometable;
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<entry>
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<type>double precision</type>
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</entry>
8216-
<entry>(sum(<replaceable class="parameter">Y</replaceable>) *
8217-
sum(<replaceable class="parameter">X</replaceable>^2) - sum(<replaceable
8218-
class="parameter">X</replaceable>) * sum(<replaceable
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class="parameter">X</replaceable>*<replaceable
8220-
class="parameter">Y</replaceable>)) / (<replaceable
8221-
class="parameter">N</replaceable> * sum(<replaceable
8222-
class="parameter">X</replaceable>^2) - sum(<replaceable
8223-
class="parameter">X</replaceable>)^2)</entry>
8196+
<entry>y-intercept of the least-squares-fit linear equation
8197+
determined by the (<replaceable
8198+
class="parameter">X</replaceable>, <replaceable
8199+
class="parameter">Y</replaceable>) pairs</entry>
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</row>
82258201

82268202
<row>
@@ -8233,17 +8209,7 @@ SELECT count(*) FROM sometable;
82338209
<entry>
82348210
<type>double precision</type>
82358211
</entry>
8236-
<entry>(<replaceable class="parameter">N</replaceable> *
8237-
sum(<replaceable class="parameter">X</replaceable>*<replaceable
8238-
class="parameter">Y</replaceable>) - sum(<replaceable
8239-
class="parameter">X</replaceable>) * sum(<replaceable
8240-
class="parameter">Y</replaceable>))^2 / ((<replaceable
8241-
class="parameter">N</replaceable> * sum(<replaceable
8242-
class="parameter">X</replaceable>^2) - sum(<replaceable
8243-
class="parameter">X</replaceable>)^2) * (<replaceable
8244-
class="parameter">N</replaceable> * sum(<replaceable
8245-
class="parameter">Y</replaceable>^2) - sum(<replaceable
8246-
class="parameter">Y</replaceable>)^2))</entry>
8212+
<entry>square of the correlation coefficient</entry>
82478213
</row>
82488214

82498215
<row>
@@ -8259,14 +8225,9 @@ SELECT count(*) FROM sometable;
82598225
<entry>
82608226
<type>double precision</type>
82618227
</entry>
8262-
<entry>(<replaceable class="parameter">N</replaceable> *
8263-
sum(<replaceable class="parameter">X</replaceable>*<replaceable
8264-
class="parameter">Y</replaceable>) - sum(<replaceable
8265-
class="parameter">X</replaceable>) * sum(<replaceable
8266-
class="parameter">Y</replaceable>)) / (<replaceable
8267-
class="parameter">N</replaceable> * sum(<replaceable
8268-
class="parameter">X</replaceable>^2) - sum(<replaceable
8269-
class="parameter">X</replaceable>)^2)</entry>
8228+
<entry>slope of the least-squares-fit linear equation determined
8229+
by the (<replaceable class="parameter">X</replaceable>,
8230+
<replaceable class="parameter">Y</replaceable>) pairs</entry>
82708231
</row>
82718232

82728233
<row>
@@ -8279,9 +8240,11 @@ SELECT count(*) FROM sometable;
82798240
<entry>
82808241
<type>double precision</type>
82818242
</entry>
8282-
<entry>sum(<replaceable class="parameter">X</replaceable>^2) -
8283-
sum(<replaceable class="parameter">X</replaceable>)^2 / <replaceable
8284-
class="parameter">N</replaceable></entry>
8243+
<entry><literal>sum(<replaceable
8244+
class="parameter">X</replaceable>^2) - sum(<replaceable
8245+
class="parameter">X</replaceable>)^2/<replaceable
8246+
class="parameter">N</replaceable></literal> (<quote>sum of
8247+
squares</quote> of the independent variable)</entry>
82858248
</row>
82868249

82878250
<row>
@@ -8294,11 +8257,14 @@ SELECT count(*) FROM sometable;
82948257
<entry>
82958258
<type>double precision</type>
82968259
</entry>
8297-
<entry>sum(<replaceable class="parameter">X</replaceable>*<replaceable
8260+
<entry><literal>sum(<replaceable
8261+
class="parameter">X</replaceable>*<replaceable
82988262
class="parameter">Y</replaceable>) - sum(<replaceable
82998263
class="parameter">X</replaceable>) * sum(<replaceable
8300-
class="parameter">Y</replaceable>) / <replaceable
8301-
class="parameter">N</replaceable></entry>
8264+
class="parameter">Y</replaceable>)/<replaceable
8265+
class="parameter">N</replaceable></literal> (<quote>sum of
8266+
products</quote> of independent times dependent
8267+
variable)</entry>
83028268
</row>
83038269

83048270
<row>
@@ -8311,9 +8277,11 @@ SELECT count(*) FROM sometable;
83118277
<entry>
83128278
<type>double precision</type>
83138279
</entry>
8314-
<entry>sum(<replaceable class="parameter">Y</replaceable>^2) -
8315-
sum(<replaceable class="parameter">Y</replaceable>)^2 / <replaceable
8316-
class="parameter">N</replaceable></entry>
8280+
<entry><literal>sum(<replaceable
8281+
class="parameter">Y</replaceable>^2) - sum(<replaceable
8282+
class="parameter">Y</replaceable>)^2/<replaceable
8283+
class="parameter">N</replaceable></literal> (<quote>sum of
8284+
squares</quote> of the dependent variable)</entry>
83178285
</row>
83188286

83198287
<row>

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