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Re-implement division for numeric values using the traditional "schoolbook"

algorithm. This is a good deal slower than our old roundoff-error-pronecode for long inputs, so we keep the old code for use in the transcendentalfunctions, where everything is approximate anyway. Also create auser-accessible function div(numeric, numeric) to provide access to theexact result of trunc(x/y) --- since the regular numeric / operator willround off its result, simply computing that expression in SQL doesn'treliably give the desired answer. This fixes bug #3387 and various relatedcorner cases, and improves the usefulness of PG for high-precision integerarithmetic.

1 parentb6f0ad4 commita0fad97Copy full SHA for a0fad97

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7 files changed

+470

-32

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doc/src/sgml
- func.sgml
src
- backend/utils/adt
  - numeric.c
- include
  - catalog
    - catversion.h
    - pg_proc.h
  - utils
    - builtins.h
- test/regress
  - expected
    - numeric.out
  - sql
    - numeric.sql

7 files changed

+470

-32

lines changed

`‎doc/src/sgml/func.sgml‎`

Lines changed: 13 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.426 2008/04/0416:57:21 momjian Exp $ -->`
	`1`	`+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.427 2008/04/0418:45:36 tgl Exp $ -->`
`2`	`2`
`3`	`3`	`<chapter id="functions">`
`4`	`4`	`<title>Functions and Operators</title>`
`@@ -617,6 +617,9 @@`
`617`	`617`	`<indexterm>`
`618`	`618`	`<primary>degrees</primary>`
`619`	`619`	`</indexterm>`
	`620`	`+ <indexterm>`
	`621`	`+ <primary>div</primary>`
	`622`	`+ </indexterm>`
`620`	`623`	`<indexterm>`
`621`	`624`	`<primary>exp</primary>`
`622`	`625`	`</indexterm>`
`@@ -717,6 +720,15 @@`
`717`	`720`	`<entry><literal>28.6478897565412</literal></entry>`
`718`	`721`	`</row>`
`719`	`722`
	`723`	`+ <row>`
	`724`	`+ <entry><literal><function>div</function>(<parameter>y</parameter> <type>numeric</>,`
	`725`	`+ <parameter>x</parameter> <type>numeric</>)</literal></entry>`
	`726`	`+ <entry><type>numeric</></entry>`
	`727`	`+ <entry>integer quotient of <parameter>y</parameter>/<parameter>x</parameter></entry>`
	`728`	`+ <entry><literal>div(9,4)</literal></entry>`
	`729`	`+ <entry><literal>2</literal></entry>`
	`730`	`+ </row>`
	`731`	`+`
`720`	`732`	`<row>`
`721`	`733`	`<entry><literal><function>exp</function>(<type>dp</type> or <type>numeric</type>)</literal></entry>`
`722`	`734`	`<entry>(same as input)</entry>`

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Commita0fad97

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7 files changed

7 files changed

`‎doc/src/sgml/func.sgml‎`

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