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Department of marginal improvements: teach tupconvert.c to avoid doing a

physical conversion when there are dropped columns in the same places inthe input and output tupdescs. This avoids possible performance loss fromthe recent patch to improve dropped-column handling, in some cases wherethe old code would have worked.

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+33

-11

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src/backend/access/common
- tupconvert.c

1 file changed

+33

-11

lines changed

`‎src/backend/access/common/tupconvert.c`

Lines changed: 33 additions & 11 deletions

Original file line number	Diff line number	Diff line change
`@@ -14,7 +14,7 @@`
`14`	`14`	`*`
`15`	`15`	`*`
`16`	`16`	`* IDENTIFICATION`
`17`		`- * $PostgreSQL: pgsql/src/backend/access/common/tupconvert.c,v 1.1 2009/08/06 20:44:31 tgl Exp $`
	`17`	`+ * $PostgreSQL: pgsql/src/backend/access/common/tupconvert.c,v 1.2 2009/08/17 20:34:31 tgl Exp $`
`18`	`18`	`*`
`19`	`19`	`*-------------------------------------------------------------------------`
`20`	`20`	`*/`
`@@ -146,11 +146,22 @@ convert_tuples_by_position(TupleDesc indesc,`
`146`	`146`	`{`
`147`	`147`	`for (i=0;i<n;i++)`
`148`	`148`	`{`
`149`		`-if (attrMap[i]!= (i+1))`
`150`		`-{`
`151`		`-same= false;`
`152`		`-break;`
`153`		`-}`
	`149`	`+if (attrMap[i]== (i+1))`
	`150`	`+continue;`
	`151`	`+`
	`152`	`+/*`
	`153`	`+ * If it's a dropped column and the corresponding input`
	`154`	`+ * column is also dropped, we needn't convert. However,`
	`155`	`+ * attlen and attalign must agree.`
	`156`	`+ */`
	`157`	`+if (attrMap[i]==0&&`
	`158`	`+indesc->attrs[i]->attisdropped&&`
	`159`	`+indesc->attrs[i]->attlen==outdesc->attrs[i]->attlen&&`
	`160`	`+indesc->attrs[i]->attalign==outdesc->attrs[i]->attalign)`
	`161`	`+continue;`
	`162`	`+`
	`163`	`+same= false;`
	`164`	`+break;`
`154`	`165`	`}`
`155`	`166`	`}`
`156`	`167`	`else`
`@@ -255,11 +266,22 @@ convert_tuples_by_name(TupleDesc indesc,`
`255`	`266`	`same= true;`
`256`	`267`	`for (i=0;i<n;i++)`
`257`	`268`	`{`
`258`		`-if (attrMap[i]!= (i+1))`
`259`		`-{`
`260`		`-same= false;`
`261`		`-break;`
`262`		`-}`
	`269`	`+if (attrMap[i]== (i+1))`
	`270`	`+continue;`
	`271`	`+`
	`272`	`+/*`
	`273`	`+ * If it's a dropped column and the corresponding input`
	`274`	`+ * column is also dropped, we needn't convert. However,`
	`275`	`+ * attlen and attalign must agree.`
	`276`	`+ */`
	`277`	`+if (attrMap[i]==0&&`
	`278`	`+indesc->attrs[i]->attisdropped&&`
	`279`	`+indesc->attrs[i]->attlen==outdesc->attrs[i]->attlen&&`
	`280`	`+indesc->attrs[i]->attalign==outdesc->attrs[i]->attalign)`
	`281`	`+continue;`
	`282`	`+`
	`283`	`+same= false;`
	`284`	`+break;`
`263`	`285`	`}`
`264`	`286`	`}`
`265`	`287`	`else`

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`‎src/backend/access/common/tupconvert.c`

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