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Implement width_bucket() for the float8 data type.

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The implementation is somewhat ugly logic-wise, but I don't see an
easy way to make it more concise.

When writing this, I noticed that my previous implementation of
width_bucket() doesn't handle NaN correctly:

    postgres=# select width_bucket('NaN', 1, 5, 5);
     width_bucket
    --------------
                6
    (1 row)

AFAICS SQL:2003 does not define a NaN value, so it doesn't address how
width_bucket() should behave here. The patch changes width_bucket() so
that ereport(ERROR) is raised if NaN is specified for the operand or the
lower or upper bounds to width_bucket(). For float8, NaN is disallowed
for any of the floating-point inputs, and +/- infinity is disallowed
for the histogram bounds (but allowed for the operand).

Update docs and regression tests, bump the catversion.
This commit is contained in:
Neil Conway
2007-01-16 21:41:14 +00:00
parent da07c81fe3
commit cf57ef4e50
8 changed files with 210 additions and 69 deletions
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12
doc/src/sgml/func.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.350 2007/01/12 23:34:54 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.351 2007/01/16 21:41:12 neilc Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
@@ -854,6 +854,16 @@
<entry><literal>width_bucket(5.35, 0.024, 10.06, 5)</literal></entry>
<entry><literal>3</literal></entry>
</row>
<row>
<entry><literal><function>width_bucket</function>(<parameter>op</parameter> <type>dp</type>, <parameter>b1</parameter> <type>dp</type>, <parameter>b2</parameter> <type>dp</type>, <parameter>count</parameter> <type>int</type>)</literal></entry>
<entry><type>int</type></entry>
<entry>return the bucket to which <parameter>operand</> would
be assigned in an equidepth histogram with <parameter>count</>
buckets, in the range <parameter>b1</> to <parameter>b2</></entry>
<entry><literal>width_bucket(5.35, 0.024, 10.06, 5)</literal></entry>
<entry><literal>3</literal></entry>
</row>
</tbody>
</tgroup>
</table>