diff options
Diffstat (limited to 'src/backend/parser/parse_agg.c')
| -rw-r--r-- | src/backend/parser/parse_agg.c | 84 |
1 files changed, 74 insertions, 10 deletions
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c index e776f695000..a244d0398ce 100644 --- a/src/backend/parser/parse_agg.c +++ b/src/backend/parser/parse_agg.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.4 1997/12/22 05:42:19 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.5 1998/01/04 04:31:14 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -18,14 +18,17 @@ #include "postgres.h" #include "access/heapam.h" #include "catalog/pg_aggregate.h" +#include "catalog/pg_type.h" #include "nodes/nodeFuncs.h" #include "nodes/primnodes.h" #include "nodes/relation.h" #include "optimizer/clauses.h" #include "parser/parse_agg.h" +#include "parser/parse_expr.h" #include "parser/parse_node.h" #include "parser/parse_target.h" #include "utils/syscache.h" +#include "utils/lsyscache.h" static bool contain_agg_clause(Node *clause); static bool exprIsAggOrGroupCol(Node *expr, List *groupClause); @@ -276,7 +279,8 @@ parseCheckAggregates(ParseState *pstate, Query *qry) Aggreg * -ParseAgg(char *aggname, Oid basetype, Node *target) +ParseAgg(ParseState *pstate, char *aggname, Oid basetype, + List *target, int precedence) { Oid fintype; Oid vartype; @@ -284,7 +288,8 @@ ParseAgg(char *aggname, Oid basetype, Node *target) Form_pg_aggregate aggform; Aggreg *aggreg; HeapTuple theAggTuple; - + bool usenulls = false; + theAggTuple = SearchSysCacheTuple(AGGNAME, PointerGetDatum(aggname), ObjectIdGetDatum(basetype), 0, 0); @@ -293,21 +298,78 @@ ParseAgg(char *aggname, Oid basetype, Node *target) elog(WARN, "aggregate %s does not exist", aggname); } + /* + * We do a major hack for count(*) here. + * + * Count(*) poses several problems. First, we need a field that is + * guaranteed to be in the range table, and unique. Using a constant + * causes the optimizer to properly remove the aggragate from any + * elements of the query. + * Using just 'oid', which can not be null, in the parser fails on: + * + * select count(*) from tab1, tab2 -- oid is not unique + * select count(*) from viewtable -- views don't have real oids + * + * So, for an aggregate with parameter '*', we use the first valid + * range table entry, and pick the first column from the table. + * We set a flag to count nulls, because we could have nulls in + * that column. + */ + + if (nodeTag(lfirst(target)) == T_Const) + { + Const *con = (Const *)lfirst(target); + + if (con->consttype == UNKNOWNOID && VARSIZE(con->constvalue) == VARHDRSZ) + { + Attr *attr = makeNode(Attr); + List *rtable, *rlist; + RangeTblEntry *first_valid_rte; + + Assert(lnext(target) == NULL); + + if (pstate->p_is_rule) + rtable = lnext(lnext(pstate->p_rtable)); + else + rtable = pstate->p_rtable; + + first_valid_rte = NULL; + foreach(rlist, rtable) + { + RangeTblEntry *rte = lfirst(rlist); + + /* only entries on outer(non-function?) scope */ + if (!rte->inFromCl && rte != pstate->p_target_rangetblentry) + continue; + + first_valid_rte =rte; + break; + } + if (first_valid_rte == NULL) + elog(WARN, "Can't find column to do aggregate(*) on."); + + attr->relname = first_valid_rte->refname; + attr->attrs = lcons(makeString( + get_attname(first_valid_rte->relid,1)),NIL); + + lfirst(target) = transformExpr(pstate, (Node *) attr, precedence); + usenulls = true; + } + } + aggform = (Form_pg_aggregate) GETSTRUCT(theAggTuple); fintype = aggform->aggfinaltype; xfn1 = aggform->aggtransfn1; - if (nodeTag(target) != T_Var && nodeTag(target) != T_Expr) - elog(WARN, "parser: aggregate can only be applied on an attribute or expression"); - + /* only aggregates with transfn1 need a base type */ if (OidIsValid(xfn1)) { basetype = aggform->aggbasetype; - if (nodeTag(target) == T_Var) - vartype = ((Var *) target)->vartype; + if (nodeTag(lfirst(target)) == T_Var) + vartype = ((Var *) lfirst(target))->vartype; else - vartype = ((Expr *) target)->typeOid; + vartype = ((Expr *) lfirst(target))->typeOid; if (basetype != vartype) { @@ -327,7 +389,9 @@ ParseAgg(char *aggname, Oid basetype, Node *target) aggreg->basetype = aggform->aggbasetype; aggreg->aggtype = fintype; - aggreg->target = target; + aggreg->target = lfirst(target); + if (usenulls) + aggreg->usenulls = true; return aggreg; } |