diff options
Diffstat (limited to 'src/backend/parser/parse_clause.c')
| -rw-r--r-- | src/backend/parser/parse_clause.c | 93 |
1 files changed, 81 insertions, 12 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c index 54c5cb39e8e..54bb867631e 100644 --- a/src/backend/parser/parse_clause.c +++ b/src/backend/parser/parse_clause.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.196 2010/02/07 20:48:10 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.197 2010/02/12 17:33:20 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -72,6 +72,8 @@ static Node *transformFromClauseItem(ParseState *pstate, Node *n, Relids *containedRels); static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype, Var *l_colvar, Var *r_colvar); +static void checkExprIsVarFree(ParseState *pstate, Node *n, + const char *constructName); static TargetEntry *findTargetlistEntrySQL92(ParseState *pstate, Node *node, List **tlist, int clause); static TargetEntry *findTargetlistEntrySQL99(ParseState *pstate, Node *node, @@ -85,6 +87,8 @@ static List *addTargetToGroupList(ParseState *pstate, TargetEntry *tle, List *grouplist, List *targetlist, int location, bool resolveUnknown); static WindowClause *findWindowClause(List *wclist, const char *name); +static Node *transformFrameOffset(ParseState *pstate, int frameOptions, + Node *clause); /* @@ -1177,10 +1181,28 @@ transformLimitClause(ParseState *pstate, Node *clause, qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName); - /* - * LIMIT can't refer to any vars or aggregates of the current query - */ - if (contain_vars_of_level(qual, 0)) + /* LIMIT can't refer to any vars or aggregates of the current query */ + checkExprIsVarFree(pstate, qual, constructName); + + return qual; +} + +/* + * checkExprIsVarFree + * Check that given expr has no Vars of the current query level + * (and no aggregates or window functions, either). + * + * This is used to check expressions that have to have a consistent value + * across all rows of the query, such as a LIMIT. Arguably it should reject + * volatile functions, too, but we don't do that --- whatever value the + * function gives on first execution is what you get. + * + * constructName does not affect the semantics, but is used in error messages + */ +static void +checkExprIsVarFree(ParseState *pstate, Node *n, const char *constructName) +{ + if (contain_vars_of_level(n, 0)) { ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), @@ -1188,10 +1210,10 @@ transformLimitClause(ParseState *pstate, Node *clause, errmsg("argument of %s must not contain variables", constructName), parser_errposition(pstate, - locate_var_of_level(qual, 0)))); + locate_var_of_level(n, 0)))); } if (pstate->p_hasAggs && - checkExprHasAggs(qual)) + checkExprHasAggs(n)) { ereport(ERROR, (errcode(ERRCODE_GROUPING_ERROR), @@ -1199,10 +1221,10 @@ transformLimitClause(ParseState *pstate, Node *clause, errmsg("argument of %s must not contain aggregate functions", constructName), parser_errposition(pstate, - locate_agg_of_level(qual, 0)))); + locate_agg_of_level(n, 0)))); } if (pstate->p_hasWindowFuncs && - checkExprHasWindowFuncs(qual)) + checkExprHasWindowFuncs(n)) { ereport(ERROR, (errcode(ERRCODE_WINDOWING_ERROR), @@ -1210,10 +1232,8 @@ transformLimitClause(ParseState *pstate, Node *clause, errmsg("argument of %s must not contain window functions", constructName), parser_errposition(pstate, - locate_windowfunc(qual)))); + locate_windowfunc(n)))); } - - return qual; } @@ -1664,6 +1684,11 @@ transformWindowDefinitions(ParseState *pstate, windef->refname), parser_errposition(pstate, windef->location))); wc->frameOptions = windef->frameOptions; + /* Process frame offset expressions */ + wc->startOffset = transformFrameOffset(pstate, wc->frameOptions, + windef->startOffset); + wc->endOffset = transformFrameOffset(pstate, wc->frameOptions, + windef->endOffset); wc->winref = winref; result = lappend(result, wc); @@ -2166,3 +2191,47 @@ findWindowClause(List *wclist, const char *name) return NULL; } + +/* + * transformFrameOffset + * Process a window frame offset expression + */ +static Node * +transformFrameOffset(ParseState *pstate, int frameOptions, Node *clause) +{ + const char *constructName = NULL; + Node *node; + + /* Quick exit if no offset expression */ + if (clause == NULL) + return NULL; + + /* Transform the raw expression tree */ + node = transformExpr(pstate, clause); + + if (frameOptions & FRAMEOPTION_ROWS) + { + /* + * Like LIMIT clause, simply coerce to int8 + */ + constructName = "ROWS"; + node = coerce_to_specific_type(pstate, node, INT8OID, constructName); + } + else if (frameOptions & FRAMEOPTION_RANGE) + { + /* + * this needs a lot of thought to decide how to support in the + * context of Postgres' extensible datatype framework + */ + constructName = "RANGE"; + /* error was already thrown by gram.y, this is just a backstop */ + elog(ERROR, "window frame with value offset is not implemented"); + } + else + Assert(false); + + /* Disallow variables and aggregates in frame offsets */ + checkExprIsVarFree(pstate, node, constructName); + + return node; +} |