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Commit6dfe64e

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Teach ruleutils to drill down into RECORD-type Vars in the same way
that the parser now can, so that it can reverse-list cases involvingFieldSelect from a RECORD Var.
1 parent83b72ee commit6dfe64e

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1 file changed

+188
-32
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1 file changed

+188
-32
lines changed

‎src/backend/utils/adt/ruleutils.c

Lines changed: 188 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*back to source text
44
*
55
* IDENTIFICATION
6-
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.197 2005/05/30 01:57:27 tgl Exp $
6+
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.198 2005/05/31 03:03:59 tgl Exp $
77
*
88
* This software is copyrighted by Jan Wieck - Hamburg.
99
*
@@ -55,6 +55,7 @@
5555
#include"catalog/pg_shadow.h"
5656
#include"catalog/pg_trigger.h"
5757
#include"executor/spi.h"
58+
#include"funcapi.h"
5859
#include"lib/stringinfo.h"
5960
#include"miscadmin.h"
6061
#include"nodes/makefuncs.h"
@@ -2421,30 +2422,18 @@ get_utility_query_def(Query *query, deparse_context *context)
24212422

24222423

24232424
/*
2424-
* Get theschemaname, refname and attname for a (possibly nonlocal) Var.
2425+
* Get theRTE referenced by a (possibly nonlocal) Var.
24252426
*
24262427
* In some cases (currently only when recursing into an unnamed join)
24272428
* the Var's varlevelsup has to be interpreted with respect to a context
24282429
* above the current one; levelsup indicates the offset.
2429-
*
2430-
* schemaname is usually returned as NULL.It will be non-null only if
2431-
* use of the unqualified refname would find the wrong RTE.
2432-
*
2433-
* refname will be returned as NULL if the Var references an unnamed join.
2434-
* In this case the Var *must* be displayed without any qualification.
2435-
*
2436-
* attname will be returned as NULL if the Var represents a whole tuple
2437-
* of the relation. (Typically we'd want to display the Var as "foo.*",
2438-
* but it's convenient to return NULL to make it easier for callers to
2439-
* distinguish this case.)
24402430
*/
2441-
staticvoid
2442-
get_names_for_var(Var*var,intlevelsup,deparse_context*context,
2443-
char**schemaname,char**refname,char**attname)
2431+
staticRangeTblEntry*
2432+
get_rte_for_var(Var*var,intlevelsup,deparse_context*context)
24442433
{
2434+
RangeTblEntry*rte;
24452435
intnetlevelsup;
24462436
deparse_namespace*dpns;
2447-
RangeTblEntry*rte;
24482437

24492438
/* Find appropriate nesting depth */
24502439
netlevelsup=var->varlevelsup+levelsup;
@@ -2465,6 +2454,36 @@ get_names_for_var(Var *var, int levelsup, deparse_context *context,
24652454
rte=NULL;
24662455
if (rte==NULL)
24672456
elog(ERROR,"bogus varno: %d",var->varno);
2457+
returnrte;
2458+
}
2459+
2460+
2461+
/*
2462+
* Get the schemaname, refname and attname for a (possibly nonlocal) Var.
2463+
*
2464+
* In some cases (currently only when recursing into an unnamed join)
2465+
* the Var's varlevelsup has to be interpreted with respect to a context
2466+
* above the current one; levelsup indicates the offset.
2467+
*
2468+
* schemaname is usually returned as NULL.It will be non-null only if
2469+
* use of the unqualified refname would find the wrong RTE.
2470+
*
2471+
* refname will be returned as NULL if the Var references an unnamed join.
2472+
* In this case the Var *must* be displayed without any qualification.
2473+
*
2474+
* attname will be returned as NULL if the Var represents a whole tuple
2475+
* of the relation. (Typically we'd want to display the Var as "foo.*",
2476+
* but it's convenient to return NULL to make it easier for callers to
2477+
* distinguish this case.)
2478+
*/
2479+
staticvoid
2480+
get_names_for_var(Var*var,intlevelsup,deparse_context*context,
2481+
char**schemaname,char**refname,char**attname)
2482+
{
2483+
RangeTblEntry*rte;
2484+
2485+
/* Find appropriate RTE */
2486+
rte=get_rte_for_var(var,levelsup,context);
24682487

24692488
/* Emit results */
24702489
*schemaname=NULL;/* default assumptions */
@@ -2505,7 +2524,8 @@ get_names_for_var(Var *var, int levelsup, deparse_context *context,
25052524
var->varattno-1);
25062525
if (IsA(aliasvar,Var))
25072526
{
2508-
get_names_for_var(aliasvar,netlevelsup,context,
2527+
get_names_for_var(aliasvar,
2528+
var->varlevelsup+levelsup,context,
25092529
schemaname,refname,attname);
25102530
return;
25112531
}
@@ -2521,6 +2541,127 @@ get_names_for_var(Var *var, int levelsup, deparse_context *context,
25212541
*attname=get_rte_attribute_name(rte,var->varattno);
25222542
}
25232543

2544+
2545+
/*
2546+
* Get the name of a field of a Var of type RECORD.
2547+
*
2548+
* Since no actual table or view column is allowed to have type RECORD, such
2549+
* a Var must refer to a JOIN or FUNCTION RTE or to a subquery output. We
2550+
* drill down to find the ultimate defining expression and attempt to infer
2551+
* the field name from it. We ereport if we can't determine the name.
2552+
*
2553+
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
2554+
*
2555+
* Note: this has essentially the same logic as the parser's
2556+
* expandRecordVariable() function, but we are dealing with a different
2557+
* representation of the input context, and we only need one field name not
2558+
* a TupleDesc.
2559+
*/
2560+
staticconstchar*
2561+
get_name_for_var_field(Var*var,intfieldno,
2562+
intlevelsup,deparse_context*context)
2563+
{
2564+
RangeTblEntry*rte;
2565+
AttrNumberattnum;
2566+
TupleDesctupleDesc;
2567+
Node*expr;
2568+
2569+
/* Check my caller didn't mess up */
2570+
Assert(IsA(var,Var));
2571+
Assert(var->vartype==RECORDOID);
2572+
2573+
/* Find appropriate RTE */
2574+
rte=get_rte_for_var(var,levelsup,context);
2575+
2576+
attnum=var->varattno;
2577+
2578+
if (attnum==InvalidAttrNumber)
2579+
{
2580+
/* Var is whole-row reference to RTE, so select the right field */
2581+
returnget_rte_attribute_name(rte,fieldno);
2582+
}
2583+
2584+
expr= (Node*)var;/* default if we can't drill down */
2585+
2586+
switch (rte->rtekind)
2587+
{
2588+
caseRTE_RELATION:
2589+
caseRTE_SPECIAL:
2590+
/*
2591+
* This case should not occur: a column of a table shouldn't have
2592+
* type RECORD. Fall through and fail (most likely) at the
2593+
* bottom.
2594+
*/
2595+
break;
2596+
caseRTE_SUBQUERY:
2597+
{
2598+
/* Subselect-in-FROM: examine sub-select's output expr */
2599+
TargetEntry*ste=get_tle_by_resno(rte->subquery->targetList,
2600+
attnum);
2601+
2602+
if (ste==NULL||ste->resjunk)
2603+
elog(ERROR,"subquery %s does not have attribute %d",
2604+
rte->eref->aliasname,attnum);
2605+
expr= (Node*)ste->expr;
2606+
if (IsA(expr,Var))
2607+
{
2608+
/*
2609+
* Recurse into the sub-select to see what its Var refers
2610+
* to. We have to build an additional level of namespace
2611+
* to keep in step with varlevelsup in the subselect.
2612+
*/
2613+
deparse_namespacemydpns;
2614+
constchar*result;
2615+
2616+
mydpns.rtable=rte->subquery->rtable;
2617+
mydpns.outer_varno=mydpns.inner_varno=0;
2618+
mydpns.outer_rte=mydpns.inner_rte=NULL;
2619+
2620+
context->namespaces=lcons(&mydpns,context->namespaces);
2621+
2622+
result=get_name_for_var_field((Var*)expr,fieldno,
2623+
0,context);
2624+
2625+
context->namespaces=list_delete_first(context->namespaces);
2626+
2627+
returnresult;
2628+
}
2629+
/* else fall through to inspect the expression */
2630+
}
2631+
break;
2632+
caseRTE_JOIN:
2633+
/* Join RTE --- recursively inspect the alias variable */
2634+
Assert(attnum>0&&attnum <=list_length(rte->joinaliasvars));
2635+
expr= (Node*)list_nth(rte->joinaliasvars,attnum-1);
2636+
if (IsA(expr,Var))
2637+
returnget_name_for_var_field((Var*)expr,fieldno,
2638+
var->varlevelsup+levelsup,
2639+
context);
2640+
/* else fall through to inspect the expression */
2641+
break;
2642+
caseRTE_FUNCTION:
2643+
/*
2644+
* We couldn't get here unless a function is declared with one
2645+
* of its result columns as RECORD, which is not allowed.
2646+
*/
2647+
break;
2648+
}
2649+
2650+
/*
2651+
* We now have an expression we can't expand any more, so see if
2652+
* get_expr_result_type() can do anything with it. If not, pass
2653+
* to lookup_rowtype_tupdesc() which will probably fail, but will
2654+
* give an appropriate error message while failing.
2655+
*/
2656+
if (get_expr_result_type(expr,NULL,&tupleDesc)!=TYPEFUNC_COMPOSITE)
2657+
tupleDesc=lookup_rowtype_tupdesc(exprType(expr),exprTypmod(expr));
2658+
2659+
/* Got the tupdesc, so we can extract the field name */
2660+
Assert(fieldno >=1&&fieldno <=tupleDesc->natts);
2661+
returnNameStr(tupleDesc->attrs[fieldno-1]->attname);
2662+
}
2663+
2664+
25242665
/*
25252666
* find_rte_by_refname- look up an RTE by refname in a deparse context
25262667
*
@@ -3109,33 +3250,48 @@ get_rule_expr(Node *node, deparse_context *context,
31093250
caseT_FieldSelect:
31103251
{
31113252
FieldSelect*fselect= (FieldSelect*)node;
3112-
OidargType=exprType((Node*)fselect->arg);
3113-
Oidtyprelid;
3114-
char*fieldname;
3253+
Node*arg= (Node*)fselect->arg;
3254+
intfno=fselect->fieldnum;
3255+
constchar*fieldname;
31153256
boolneed_parens;
31163257

3117-
/* lookup arg type and get the field name */
3118-
typrelid=get_typ_typrelid(argType);
3119-
if (!OidIsValid(typrelid))
3120-
elog(ERROR,"argument type %s of FieldSelect is not a tuple type",
3121-
format_type_be(argType));
3122-
fieldname=get_relid_attribute_name(typrelid,
3123-
fselect->fieldnum);
3124-
31253258
/*
31263259
* Parenthesize the argument unless it's an ArrayRef or
31273260
* another FieldSelect. Note in particular that it would
31283261
* be WRONG to not parenthesize a Var argument; simplicity
31293262
* is not the issue here, having the right number of names
31303263
* is.
31313264
*/
3132-
need_parens= !IsA(fselect->arg,ArrayRef)&&
3133-
!IsA(fselect->arg,FieldSelect);
3265+
need_parens= !IsA(arg,ArrayRef)&& !IsA(arg,FieldSelect);
31343266
if (need_parens)
31353267
appendStringInfoChar(buf,'(');
3136-
get_rule_expr((Node*)fselect->arg,context, true);
3268+
get_rule_expr(arg,context, true);
31373269
if (need_parens)
31383270
appendStringInfoChar(buf,')');
3271+
3272+
/*
3273+
* If it's a Var of type RECORD, we have to find what the Var
3274+
* refers to; otherwise we can use get_expr_result_type.
3275+
* If that fails, we try lookup_rowtype_tupdesc, which will
3276+
* probably fail too, but will ereport an acceptable message.
3277+
*/
3278+
if (IsA(arg,Var)&&
3279+
((Var*)arg)->vartype==RECORDOID)
3280+
fieldname=get_name_for_var_field((Var*)arg,fno,
3281+
0,context);
3282+
else
3283+
{
3284+
TupleDesctupdesc;
3285+
3286+
if (get_expr_result_type(arg,NULL,&tupdesc)!=TYPEFUNC_COMPOSITE)
3287+
tupdesc=lookup_rowtype_tupdesc(exprType(arg),
3288+
exprTypmod(arg));
3289+
Assert(tupdesc);
3290+
/* Got the tupdesc, so we can extract the field name */
3291+
Assert(fno >=1&&fno <=tupdesc->natts);
3292+
fieldname=NameStr(tupdesc->attrs[fno-1]->attname);
3293+
}
3294+
31393295
appendStringInfo(buf,".%s",quote_identifier(fieldname));
31403296
}
31413297
break;

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