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Refactor parser's generation of Var nodes.

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Instead of passing around a pointer to the RangeTblEntry that
provides the desired column, pass a pointer to the associated
ParseNamespaceItem.  The RTE is trivially reachable from the nsitem,
and having the ParseNamespaceItem allows access to additional
information.  As proof of concept for that, add the rangetable index
to ParseNamespaceItem, and use that to get rid of RTERangeTablePosn
searches.

(I have in mind to teach the parser to generate some different
representation for Vars that are nullable by outer joins, and
keeping the necessary information in ParseNamespaceItems seems
like a reasonable approach to that.  But whether that ever
happens or not, this seems like good cleanup.)

Also refactor the code around scanRTEForColumn so that the
"fuzzy match" stuff does not leak out of parse_relation.c.

Discussion: https://postgr.es/m/26144.1576858373@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2019-12-26 11:16:42 -05:00
parent 044b319cd7
commit b541e9accb
9 changed files with 335 additions and 292 deletions
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8
src/include/parser/parse_node.h
View File

@@ -134,6 +134,8 @@ typedef Node *(*CoerceParamHook) (ParseState *pstate, Param *param,
*
* p_target_rangetblentry: target relation's entry in the rtable list.
*
* p_target_rtindex: target relation's index in the rtable list.
*
* p_is_insert: true to process assignment expressions like INSERT, false
* to process them like UPDATE. (Note this can change intra-statement, for
* cases like INSERT ON CONFLICT UPDATE.)
@@ -185,7 +187,8 @@ struct ParseState
List *p_future_ctes; /* common table exprs not yet in namespace */
CommonTableExpr *p_parent_cte; /* this query's containing CTE */
Relation p_target_relation; /* INSERT/UPDATE/DELETE target rel */
RangeTblEntry *p_target_rangetblentry; /* target rel's RTE */
RangeTblEntry *p_target_rangetblentry; /* target rel's RTE, or NULL */
int p_target_rtindex; /* target rel's RT index, or 0 */
bool p_is_insert; /* process assignment like INSERT not UPDATE */
List *p_windowdefs; /* raw representations of window clauses */
ParseExprKind p_expr_kind; /* what kind of expression we're parsing */
@@ -249,6 +252,7 @@ struct ParseState
typedef struct ParseNamespaceItem
{
RangeTblEntry *p_rte; /* The relation's rangetable entry */
int p_rtindex; /* The relation's index in the rangetable */
bool p_rel_visible; /* Relation name is visible? */
bool p_cols_visible; /* Column names visible as unqualified refs? */
bool p_lateral_only; /* Is only visible to LATERAL expressions? */
@@ -272,8 +276,6 @@ extern void setup_parser_errposition_callback(ParseCallbackState *pcbstate,
ParseState *pstate, int location);
extern void cancel_parser_errposition_callback(ParseCallbackState *pcbstate);
extern Var *make_var(ParseState *pstate, RangeTblEntry *rte, int attrno,
int location);
extern Oid transformContainerType(Oid *containerType, int32 *containerTypmod);
extern SubscriptingRef *transformContainerSubscripts(ParseState *pstate,

43
src/include/parser/parse_relation.h
View File

@@ -17,45 +17,28 @@
#include "parser/parse_node.h"
/*
* Support for fuzzily matching column.
*
* This is for building diagnostic messages, where non-exact matching
* attributes are suggested to the user. The struct's fields may be facets of
* a particular RTE, or of an entire range table, depending on context.
*/
typedef struct
{
int distance; /* Weighted distance (lowest so far) */
RangeTblEntry *rfirst; /* RTE of first */
AttrNumber first; /* Closest attribute so far */
RangeTblEntry *rsecond; /* RTE of second */
AttrNumber second; /* Second closest attribute so far */
} FuzzyAttrMatchState;
extern RangeTblEntry *refnameRangeTblEntry(ParseState *pstate,
const char *schemaname,
const char *refname,
int location,
int *sublevels_up);
extern ParseNamespaceItem *refnameNamespaceItem(ParseState *pstate,
const char *schemaname,
const char *refname,
int location,
int *sublevels_up);
extern CommonTableExpr *scanNameSpaceForCTE(ParseState *pstate,
const char *refname,
Index *ctelevelsup);
extern bool scanNameSpaceForENR(ParseState *pstate, const char *refname);
extern void checkNameSpaceConflicts(ParseState *pstate, List *namespace1,
List *namespace2);
extern int RTERangeTablePosn(ParseState *pstate,
RangeTblEntry *rte,
int *sublevels_up);
extern ParseNamespaceItem *GetNSItemByRangeTablePosn(ParseState *pstate,
int varno,
int sublevels_up);
extern RangeTblEntry *GetRTEByRangeTablePosn(ParseState *pstate,
int varno,
int sublevels_up);
extern CommonTableExpr *GetCTEForRTE(ParseState *pstate, RangeTblEntry *rte,
int rtelevelsup);
extern Node *scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte,
const char *colname, int location,
int fuzzy_rte_penalty, FuzzyAttrMatchState *fuzzystate);
extern Node *scanNSItemForColumn(ParseState *pstate, ParseNamespaceItem *nsitem,
int sublevels_up, const char *colname,
int location);
extern Node *colNameToVar(ParseState *pstate, const char *colname, bool localonly,
int location);
extern void markVarForSelectPriv(ParseState *pstate, Var *var,
@@ -122,8 +105,8 @@ extern void errorMissingColumn(ParseState *pstate,
extern void expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
int location, bool include_dropped,
List **colnames, List **colvars);
extern List *expandRelAttrs(ParseState *pstate, RangeTblEntry *rte,
int rtindex, int sublevels_up, int location);
extern List *expandNSItemAttrs(ParseState *pstate, ParseNamespaceItem *nsitem,
int sublevels_up, int location);
extern int attnameAttNum(Relation rd, const char *attname, bool sysColOK);
extern const NameData *attnumAttName(Relation rd, int attid);
extern Oid attnumTypeId(Relation rd, int attid);