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Commit1c497fa

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Avoid coercing a whole-row variable that is already coerced.
Marginal efficiency and beautification hack. I'm not sure whetherthis case ever arises currently, but the pending patch for updatetuple routing will cause it to arise.Amit KhandekarDiscussion:http://postgr.es/m/CAJ3gD9cazfppe7-wwUbabPcQ4_0SubkiPFD1+0r5_DkVNWo5yg@mail.gmail.com
1 parent60f7c0a commit1c497fa

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1 file changed

+42
-11
lines changed

1 file changed

+42
-11
lines changed

‎src/backend/rewrite/rewriteManip.c

Lines changed: 42 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1224,6 +1224,7 @@ typedef struct
12241224
/* Target type when converting whole-row vars */
12251225
Oidto_rowtype;
12261226
bool*found_whole_row;/* output flag */
1227+
boolcoerced_var;/* var is under ConvertRowTypeExpr */
12271228
}map_variable_attnos_context;
12281229

12291230
staticNode*
@@ -1267,29 +1268,58 @@ map_variable_attnos_mutator(Node *node,
12671268
/* Don't convert unless necessary. */
12681269
if (context->to_rowtype!=var->vartype)
12691270
{
1270-
ConvertRowtypeExpr*r;
1271-
12721271
/* Var itself is converted to the requested type. */
12731272
newvar->vartype=context->to_rowtype;
12741273

12751274
/*
1276-
*And a conversion node on top to convert back to the
1277-
*original type.
1275+
*If this var is already under a ConvertRowtypeExpr,
1276+
*we don't have to add another one.
12781277
*/
1279-
r=makeNode(ConvertRowtypeExpr);
1280-
r->arg= (Expr*)newvar;
1281-
r->resulttype=var->vartype;
1282-
r->convertformat=COERCE_IMPLICIT_CAST;
1283-
r->location=-1;
1284-
1285-
return (Node*)r;
1278+
if (!context->coerced_var)
1279+
{
1280+
ConvertRowtypeExpr*r;
1281+
1282+
/*
1283+
* And a conversion node on top to convert back to
1284+
* the original type.
1285+
*/
1286+
r=makeNode(ConvertRowtypeExpr);
1287+
r->arg= (Expr*)newvar;
1288+
r->resulttype=var->vartype;
1289+
r->convertformat=COERCE_IMPLICIT_CAST;
1290+
r->location=-1;
1291+
1292+
return (Node*)r;
1293+
}
12861294
}
12871295
}
12881296
}
12891297
return (Node*)newvar;
12901298
}
12911299
/* otherwise fall through to copy the var normally */
12921300
}
1301+
elseif (IsA(node,ConvertRowtypeExpr))
1302+
{
1303+
ConvertRowtypeExpr*r= (ConvertRowtypeExpr*)node;
1304+
1305+
/*
1306+
* If this is coercing a var (which is typical), convert only the var,
1307+
* as against adding another ConvertRowtypeExpr over it.
1308+
*/
1309+
if (IsA(r->arg,Var))
1310+
{
1311+
ConvertRowtypeExpr*newnode;
1312+
1313+
newnode= (ConvertRowtypeExpr*)palloc(sizeof(ConvertRowtypeExpr));
1314+
*newnode=*r;
1315+
context->coerced_var= true;
1316+
newnode->arg= (Expr*)map_variable_attnos_mutator((Node*)r->arg,context);
1317+
context->coerced_var= false;
1318+
1319+
return (Node*)newnode;
1320+
}
1321+
/* Else fall through the expression tree mutator */
1322+
}
12931323
elseif (IsA(node,Query))
12941324
{
12951325
/* Recurse into RTE subquery or not-yet-planned sublink subquery */
@@ -1321,6 +1351,7 @@ map_variable_attnos(Node *node,
13211351
context.map_length=map_length;
13221352
context.to_rowtype=to_rowtype;
13231353
context.found_whole_row=found_whole_row;
1354+
context.coerced_var= false;
13241355

13251356
*found_whole_row= false;
13261357

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