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Clarify documentation about "peer" rows in window functions

Peer rows are matching rows when ORDER BY is specified.Report by arnaud.mouronval@gmail.com, David G Johnston

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Lines changed: 2 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -13050,7 +13050,8 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;`
`13050`	`13050`	`<firstterm>Window functions</firstterm> provide the ability to perform`
`13051`	`13051`	`calculations across sets of rows that are related to the current query`
`13052`	`13052`	`row. See <xref linkend="tutorial-window"> for an introduction to this`
`13053`		`- feature.`
	`13053`	`+ feature, and <xref linkend="syntax-window-functions"> for syntax`
	`13054`	`+ details.`
`13054`	`13055`	`</para>`
`13055`	`13056`
`13056`	`13057`	`<para>`

Lines changed: 4 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -792,8 +792,9 @@ UNBOUNDED FOLLOWING`
`792`	`792`	`The default framing option is <literal>RANGE UNBOUNDED PRECEDING</>,`
`793`	`793`	`which is the same as <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND`
`794`	`794`	`CURRENT ROW</>; it sets the frame to be all rows from the partition start`
`795`		`- up through the current row's last peer in the <literal>ORDER BY</>`
`796`		`- ordering (which means all rows if there is no <literal>ORDER BY</>).`
	`795`	`+ up through the current row's last peer (a row that <literal>ORDER`
	`796`	`+ BY</> considers equivalent to the current row, or all rows if there`
	`797`	`+ is no <literal>ORDER BY</>).`
`797`	`798`	`In general, <literal>UNBOUNDED PRECEDING</> means that the frame`
`798`	`799`	`starts with the first row of the partition, and similarly`
`799`	`800`	`<literal>UNBOUNDED FOLLOWING</> means that the frame ends with the last`
`@@ -817,7 +818,7 @@ UNBOUNDED FOLLOWING`
`817`	`818`	`results if the <literal>ORDER BY</> ordering does not order the rows`
`818`	`819`	`uniquely. The <literal>RANGE</> options are designed to ensure that`
`819`	`820`	`rows that are peers in the <literal>ORDER BY</> ordering are treated`
`820`		`- alike;any twopeer rows will bebothinor both not inthe frame.`
	`821`	`+ alike;allpeer rows will be in the same frame.`
`821`	`822`	`</para>`
`822`	`823`
`823`	`824`	`<para>`

Lines changed: 2 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -1877,7 +1877,7 @@ UNBOUNDED FOLLOWING`
`1877`	`1877`	`first <firstterm>peer</> row (a row that <literal>ORDER BY</> considers`
`1878`	`1878`	`equivalent to the current row), while a <replaceable>frame_end</> of`
`1879`	`1879`	`<literal>CURRENT ROW</> means the frame ends with the last equivalent`
`1880`		`- peer. In <literal>ROWS</> mode, <literal>CURRENT ROW</> simply means`
	`1880`	`+<literal>ORDER BY</>peer. In <literal>ROWS</> mode, <literal>CURRENT ROW</> simply means`
`1881`	`1881`	`the current row.`
`1882`	`1882`	`</para>`
`1883`	`1883`
`@@ -1897,7 +1897,7 @@ UNBOUNDED FOLLOWING`
`1897`	`1897`	`which is the same as <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND`
`1898`	`1898`	`CURRENT ROW</>. With <literal>ORDER BY</>, this sets the frame to be`
`1899`	`1899`	`all rows from the partition start up through the current row's last`
`1900`		`- peer. Without <literal>ORDER BY</>, all rows of the partition are`
	`1900`	`+<literal>ORDER BY</>peer. Without <literal>ORDER BY</>, all rows of the partition are`
`1901`	`1901`	`included in the window frame, since all rows become peers of the current`
`1902`	`1902`	`row.`
`1903`	`1903`	`</para>`

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