Folks,
Neil Conway sent me a patch that sketched out a plan to make quals
visible to functions, and Korry Douglas filled in much of the rest of
what you see attached here. Mistakes are all mine. :)
Random observations:
* It appears I've botched the call to deparse_context_for_plan in
src/backend/executor/execQual.c and/or made some more fundamental
error because when testing with PL/Perl, I only see quals inside the
function when there is just one. Where are the APIs for things like
deparse_context_for_plan() documented?
* This stuff should be available to all the PLs. How might it work in
PL/PgSQL, etc.?
* The patch just appends a WHERE clause on when it finds quals in
contrib/dblink/dblink.c. While this is probably a good place to
start, it might be good to explore some kind of approach that allows
more subtlety.
* In PL/Perl, $_TD->{_quals} gets the qualifiers, but they really
should go in their own variable. I'm thinking that one should be
called $_QUAL.
* More generally, it would be nice to have the quals in some kind of
data structure so the calling code could do smarter things with them
than the current string-mashing the example code does.
Help, comments, brickbats, etc. appreciated :)
Cheers,
David.
--
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Index: contrib/dblink/dblink.c
===================================================================
RCS file: /projects/cvsroot/pgsql/contrib/dblink/dblink.c,v
retrieving revision 1.70
diff -c -c -r1.70 dblink.c
*** contrib/dblink/dblink.c 25 Mar 2008 22:42:41 -0000 1.70
--- contrib/dblink/dblink.c 25 Mar 2008 23:24:42 -0000
***************
*** 752,757 ****
--- 752,758 ----
char *conname = NULL;
remoteConn *rconn = NULL;
bool fail = true; /* default to backward
compatible */
+ ReturnSetInfo *rsi;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
***************
*** 826,831 ****
--- 827,843 ----
elog(ERROR, "wrong number of arguments");
}
+ if (sql && rsi->qual)
+ {
+ char *quals = rsinfo_get_qual_str(rsi);
+ char *qualifiedQuery = palloc(strlen(sql) + strlen("
WHERE ") +
+
strlen(quals) + 1);
+
+ sprintf(qualifiedQuery, "%s WHERE %s", sql, quals);
+
+ sql = qualifiedQuery;
+ }
+
if (!conn)
DBLINK_CONN_NOT_AVAIL;
Index: src/backend/executor/execQual.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/executor/execQual.c,v
retrieving revision 1.228
diff -c -c -r1.228 execQual.c
*** src/backend/executor/execQual.c 25 Mar 2008 22:42:43 -0000 1.228
--- src/backend/executor/execQual.c 25 Mar 2008 23:24:43 -0000
***************
*** 45,50 ****
--- 45,51 ----
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
+ #include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "parser/parse_expr.h"
#include "utils/acl.h"
***************
*** 1415,1420 ****
--- 1416,1440 ----
return result;
}
+ /*
+ *
+ * Get either an empty string or a batch of qualifiers.
+ *
+ */
+ char *
+ rsinfo_get_qual_str(ReturnSetInfo *rsinfo)
+ {
+ Node *qual;
+ List *context;
+
+ if (rsinfo->qual == NIL)
+ return pstrdup("");
+
+ qual = (Node *) make_ands_explicit(rsinfo->qual);
+ context = deparse_context_for_plan(NULL, NULL, rsinfo->rtable);
+
+ return deparse_expression(qual, context, false, false);
+ }
/*
* ExecMakeTableFunctionResult
***************
*** 1426,1431 ****
--- 1446,1452 ----
Tuplestorestate *
ExecMakeTableFunctionResult(ExprState *funcexpr,
ExprContext *econtext,
+ List *qual, List
*rtable,
TupleDesc expectedDesc,
TupleDesc *returnDesc)
{
***************
*** 1458,1463 ****
--- 1479,1486 ----
InitFunctionCallInfoData(fcinfo, NULL, 0, NULL, (Node *) &rsinfo);
rsinfo.type = T_ReturnSetInfo;
rsinfo.econtext = econtext;
+ rsinfo.qual = qual;
+ rsinfo.rtable = rtable;
rsinfo.expectedDesc = expectedDesc;
rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize);
rsinfo.returnMode = SFRM_ValuePerCall;
Index: src/backend/executor/nodeFunctionscan.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/executor/nodeFunctionscan.c,v
retrieving revision 1.46
diff -c -c -r1.46 nodeFunctionscan.c
*** src/backend/executor/nodeFunctionscan.c 29 Feb 2008 02:49:39 -0000
1.46
--- src/backend/executor/nodeFunctionscan.c 25 Mar 2008 23:24:43 -0000
***************
*** 68,73 ****
--- 68,75 ----
node->tuplestorestate = tuplestorestate =
ExecMakeTableFunctionResult(node->funcexpr,
econtext,
+
node->ss.ps.plan->qual,
+
estate->es_range_table,
node->tupdesc,
&funcTupdesc);
Index: src/include/executor/executor.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/executor/executor.h,v
retrieving revision 1.146
diff -c -c -r1.146 executor.h
*** src/include/executor/executor.h 1 Jan 2008 19:45:57 -0000 1.146
--- src/include/executor/executor.h 25 Mar 2008 23:24:43 -0000
***************
*** 171,176 ****
--- 171,177 ----
ExprDoneCond *isDone);
extern Tuplestorestate *ExecMakeTableFunctionResult(ExprState *funcexpr,
ExprContext *econtext,
+ List *qual, List
*rtable,
TupleDesc expectedDesc,
TupleDesc *returnDesc);
extern Datum ExecEvalExprSwitchContext(ExprState *expression, ExprContext
*econtext,
***************
*** 182,187 ****
--- 183,189 ----
extern int ExecCleanTargetListLength(List *targetlist);
extern TupleTableSlot *ExecProject(ProjectionInfo *projInfo,
ExprDoneCond *isDone);
+ extern char *rsinfo_get_qual_str(ReturnSetInfo *rsinfo);
/*
* prototypes from functions in execScan.c
Index: src/include/nodes/execnodes.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/nodes/execnodes.h,v
retrieving revision 1.183
diff -c -c -r1.183 execnodes.h
*** src/include/nodes/execnodes.h 1 Jan 2008 19:45:58 -0000 1.183
--- src/include/nodes/execnodes.h 25 Mar 2008 23:24:44 -0000
***************
*** 168,173 ****
--- 168,175 ----
ExprContext *econtext; /* context function is being called in
*/
TupleDesc expectedDesc; /* tuple descriptor expected by caller
*/
int allowedModes; /* bitmask: return modes caller
can handle */
+ List *qual; /* any quals to be applied to
result */
+ List *rtable;
/* result status from function (but pre-initialized by caller): */
SetFunctionReturnMode returnMode; /* actual return mode */
ExprDoneCond isDone; /* status for ValuePerCall mode */
Index: src/pl/plperl/plperl.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/pl/plperl/plperl.c,v
retrieving revision 1.138
diff -c -c -r1.138 plperl.c
*** src/pl/plperl/plperl.c 25 Mar 2008 22:42:45 -0000 1.138
--- src/pl/plperl/plperl.c 25 Mar 2008 23:24:44 -0000
***************
*** 1048,1060 ****
int i;
int count;
SV *sv;
ENTER;
SAVETMPS;
PUSHMARK(SP);
! XPUSHs(&PL_sv_undef); /* no trigger data */
for (i = 0; i < desc->nargs; i++)
{
--- 1048,1073 ----
int i;
int count;
SV *sv;
+ HV *hv;
ENTER;
SAVETMPS;
PUSHMARK(SP);
! if (fcinfo->resultinfo && ((ReturnSetInfo *)fcinfo->resultinfo)->qual)
! {
! ReturnSetInfo *rsi = (ReturnSetInfo *)fcinfo->resultinfo;
! HV *hv = newHV();
!
! hv_store_string(hv, "_quals",
newSVstring(rsinfo_get_qual_str(rsi)));
!
! XPUSHs(newRV_noinc((SV *)hv));
! }
! else
! {
! XPUSHs(&PL_sv_undef); /* no trigger or qual data */
! }
for (i = 0; i < desc->nargs; i++)
{
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