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Commit34af082

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committed
Represent BETWEEN as a special node type in raw parse trees.
Previously, gram.y itself converted BETWEEN into AND (or AND/OR) nests ofexpression comparisons. This was always as bogus as could be, but fixingit hasn't risen to the top of the to-do list. The present patch invents anA_Expr representation for BETWEEN expressions, and does the expansion tocomparison trees in parse_expr.c which is at least a slightly saner placeto be doing semantic conversions. There should be no change in the post-parse-analysis results.This does nothing for the semantic issues with BETWEEN (dubious connectionto btree-opclass semantics, and multiple evaluation of possibly volatilesubexpressions) ... but it's a necessary preliminary step before we couldfix any of that. The main immediate benefit is that preserving BETWEEN asan identifiable raw-parse-tree construct will enable better error messages.While at it, fix the code so that multiply-referenced subexpressions arephysically duplicated before being passed through transformExpr(). Thisgets rid of one of the principal reasons why transformExpr() hashistorically had to allow already-processed input.
1 parent74811c4 commit34af082

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4 files changed

+144
-36
lines changed

4 files changed

+144
-36
lines changed

‎src/backend/nodes/outfuncs.c

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2512,6 +2512,22 @@ _outAExpr(StringInfo str, const A_Expr *node)
25122512
appendStringInfoString(str," IN ");
25132513
WRITE_NODE_FIELD(name);
25142514
break;
2515+
caseAEXPR_BETWEEN:
2516+
appendStringInfoString(str," BETWEEN ");
2517+
WRITE_NODE_FIELD(name);
2518+
break;
2519+
caseAEXPR_NOT_BETWEEN:
2520+
appendStringInfoString(str," NOT_BETWEEN ");
2521+
WRITE_NODE_FIELD(name);
2522+
break;
2523+
caseAEXPR_BETWEEN_SYM:
2524+
appendStringInfoString(str," BETWEEN_SYM ");
2525+
WRITE_NODE_FIELD(name);
2526+
break;
2527+
caseAEXPR_NOT_BETWEEN_SYM:
2528+
appendStringInfoString(str," NOT_BETWEEN_SYM ");
2529+
WRITE_NODE_FIELD(name);
2530+
break;
25152531
default:
25162532
appendStringInfoString(str," ??");
25172533
break;

‎src/backend/parser/gram.y

Lines changed: 21 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -11178,7 +11178,7 @@ a_expr:c_expr{ $$ = $1; }
1117811178
* below; and all those operators will have the same precedence.
1117911179
*
1118011180
* If you add more explicitly-known operators, be sure to add them
11181-
* also to b_expr and to the MathOp listabove.
11181+
* also to b_expr and to the MathOp listbelow.
1118211182
*/
1118311183
|'+'a_expr%precUMINUS
1118411184
{$$ = (Node *) makeSimpleA_Expr(AEXPR_OP,"+",NULL,$2,@1); }
@@ -11396,51 +11396,37 @@ a_expr:c_expr{ $$ = $1; }
1139611396
{
1139711397
$$ = (Node *) makeSimpleA_Expr(AEXPR_OF,"<>",$1, (Node *)$6,@2);
1139811398
}
11399-
/*
11400-
*Ideally we would not use hard-wired operators below but
11401-
*instead use opclasses. However, mixed data types and other
11402-
*issues make this difficult:
11403-
*http://archives.postgresql.org/pgsql-hackers/2008-08/msg01142.php
11404-
*/
1140511399
|a_exprBETWEENopt_asymmetricb_exprANDb_expr%precBETWEEN
1140611400
{
11407-
$$ = makeAndExpr(
11408-
(Node *) makeSimpleA_Expr(AEXPR_OP,">=",$1,$4,@2),
11409-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<=",$1,$6,@2),
11410-
@2);
11401+
$$ = (Node *) makeSimpleA_Expr(AEXPR_BETWEEN,
11402+
"BETWEEN",
11403+
$1,
11404+
(Node *) list_make2($4,$6),
11405+
@2);
1141111406
}
1141211407
|a_exprNOTBETWEENopt_asymmetricb_exprANDb_expr%precBETWEEN
1141311408
{
11414-
$$ = makeOrExpr(
11415-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<",$1,$5,@2),
11416-
(Node *) makeSimpleA_Expr(AEXPR_OP,">",$1,$7,@2),
11417-
@2);
11409+
$$ = (Node *) makeSimpleA_Expr(AEXPR_NOT_BETWEEN,
11410+
"NOT BETWEEN",
11411+
$1,
11412+
(Node *) list_make2($5,$7),
11413+
@2);
1141811414
}
1141911415
|a_exprBETWEENSYMMETRICb_exprANDb_expr%precBETWEEN
1142011416
{
11421-
$$ = makeOrExpr(
11422-
makeAndExpr(
11423-
(Node *) makeSimpleA_Expr(AEXPR_OP,">=", $1, $4, @2),
11424-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<=", $1, $6, @2),
11425-
@2),
11426-
makeAndExpr(
11427-
(Node *) makeSimpleA_Expr(AEXPR_OP,">=", $1, $6, @2),
11428-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<=", $1, $4, @2),
11429-
@2),
11430-
@2);
11417+
$$ = (Node *) makeSimpleA_Expr(AEXPR_BETWEEN_SYM,
11418+
"BETWEEN SYMMETRIC",
11419+
$1,
11420+
(Node *) list_make2($4,$6),
11421+
@2);
1143111422
}
1143211423
|a_exprNOTBETWEENSYMMETRICb_exprANDb_expr%precBETWEEN
1143311424
{
11434-
$$ = makeAndExpr(
11435-
makeOrExpr(
11436-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<", $1, $5, @2),
11437-
(Node *) makeSimpleA_Expr(AEXPR_OP,">", $1, $7, @2),
11438-
@2),
11439-
makeOrExpr(
11440-
(Node *) makeSimpleA_Expr(AEXPR_OP,"<", $1, $7, @2),
11441-
(Node *) makeSimpleA_Expr(AEXPR_OP,">", $1, $5, @2),
11442-
@2),
11443-
@2);
11425+
$$ = (Node *) makeSimpleA_Expr(AEXPR_NOT_BETWEEN_SYM,
11426+
"NOT BETWEEN SYMMETRIC",
11427+
$1,
11428+
(Node *) list_make2($5,$7),
11429+
@2);
1144411430
}
1144511431
|a_exprIN_Pin_expr
1144611432
{

‎src/backend/parser/parse_expr.c

Lines changed: 102 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,7 @@ static Node *transformAExprDistinct(ParseState *pstate, A_Expr *a);
4848
staticNode*transformAExprNullIf(ParseState*pstate,A_Expr*a);
4949
staticNode*transformAExprOf(ParseState*pstate,A_Expr*a);
5050
staticNode*transformAExprIn(ParseState*pstate,A_Expr*a);
51+
staticNode*transformAExprBetween(ParseState*pstate,A_Expr*a);
5152
staticNode*transformBoolExpr(ParseState*pstate,BoolExpr*a);
5253
staticNode*transformFuncCall(ParseState*pstate,FuncCall*fn);
5354
staticNode*transformMultiAssignRef(ParseState*pstate,MultiAssignRef*maref);
@@ -241,6 +242,12 @@ transformExprRecurse(ParseState *pstate, Node *expr)
241242
caseAEXPR_IN:
242243
result=transformAExprIn(pstate,a);
243244
break;
245+
caseAEXPR_BETWEEN:
246+
caseAEXPR_NOT_BETWEEN:
247+
caseAEXPR_BETWEEN_SYM:
248+
caseAEXPR_NOT_BETWEEN_SYM:
249+
result=transformAExprBetween(pstate,a);
250+
break;
244251
default:
245252
elog(ERROR,"unrecognized A_Expr kind: %d",a->kind);
246253
result=NULL;/* keep compiler quiet */
@@ -1195,6 +1202,101 @@ transformAExprIn(ParseState *pstate, A_Expr *a)
11951202
returnresult;
11961203
}
11971204

1205+
staticNode*
1206+
transformAExprBetween(ParseState*pstate,A_Expr*a)
1207+
{
1208+
Node*aexpr;
1209+
Node*bexpr;
1210+
Node*cexpr;
1211+
Node*result;
1212+
Node*sub1;
1213+
Node*sub2;
1214+
List*args;
1215+
1216+
/* Deconstruct A_Expr into three subexprs */
1217+
aexpr=a->lexpr;
1218+
Assert(IsA(a->rexpr,List));
1219+
args= (List*)a->rexpr;
1220+
Assert(list_length(args)==2);
1221+
bexpr= (Node*)linitial(args);
1222+
cexpr= (Node*)lsecond(args);
1223+
1224+
/*
1225+
* Build the equivalent comparison expression. Make copies of
1226+
* multiply-referenced subexpressions for safety. (XXX this is really
1227+
* wrong since it results in multiple runtime evaluations of what may be
1228+
* volatile expressions ...)
1229+
*
1230+
* Ideally we would not use hard-wired operators here but instead use
1231+
* opclasses. However, mixed data types and other issues make this
1232+
* difficult:
1233+
* http://archives.postgresql.org/pgsql-hackers/2008-08/msg01142.php
1234+
*/
1235+
switch (a->kind)
1236+
{
1237+
caseAEXPR_BETWEEN:
1238+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,">=",
1239+
aexpr,bexpr,
1240+
a->location),
1241+
makeSimpleA_Expr(AEXPR_OP,"<=",
1242+
copyObject(aexpr),cexpr,
1243+
a->location));
1244+
result= (Node*)makeBoolExpr(AND_EXPR,args,a->location);
1245+
break;
1246+
caseAEXPR_NOT_BETWEEN:
1247+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,"<",
1248+
aexpr,bexpr,
1249+
a->location),
1250+
makeSimpleA_Expr(AEXPR_OP,">",
1251+
copyObject(aexpr),cexpr,
1252+
a->location));
1253+
result= (Node*)makeBoolExpr(OR_EXPR,args,a->location);
1254+
break;
1255+
caseAEXPR_BETWEEN_SYM:
1256+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,">=",
1257+
aexpr,bexpr,
1258+
a->location),
1259+
makeSimpleA_Expr(AEXPR_OP,"<=",
1260+
copyObject(aexpr),cexpr,
1261+
a->location));
1262+
sub1= (Node*)makeBoolExpr(AND_EXPR,args,a->location);
1263+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,">=",
1264+
copyObject(aexpr),copyObject(cexpr),
1265+
a->location),
1266+
makeSimpleA_Expr(AEXPR_OP,"<=",
1267+
copyObject(aexpr),copyObject(bexpr),
1268+
a->location));
1269+
sub2= (Node*)makeBoolExpr(AND_EXPR,args,a->location);
1270+
args=list_make2(sub1,sub2);
1271+
result= (Node*)makeBoolExpr(OR_EXPR,args,a->location);
1272+
break;
1273+
caseAEXPR_NOT_BETWEEN_SYM:
1274+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,"<",
1275+
aexpr,bexpr,
1276+
a->location),
1277+
makeSimpleA_Expr(AEXPR_OP,">",
1278+
copyObject(aexpr),cexpr,
1279+
a->location));
1280+
sub1= (Node*)makeBoolExpr(OR_EXPR,args,a->location);
1281+
args=list_make2(makeSimpleA_Expr(AEXPR_OP,"<",
1282+
copyObject(aexpr),copyObject(cexpr),
1283+
a->location),
1284+
makeSimpleA_Expr(AEXPR_OP,">",
1285+
copyObject(aexpr),copyObject(bexpr),
1286+
a->location));
1287+
sub2= (Node*)makeBoolExpr(OR_EXPR,args,a->location);
1288+
args=list_make2(sub1,sub2);
1289+
result= (Node*)makeBoolExpr(AND_EXPR,args,a->location);
1290+
break;
1291+
default:
1292+
elog(ERROR,"unrecognized A_Expr kind: %d",a->kind);
1293+
result=NULL;/* keep compiler quiet */
1294+
break;
1295+
}
1296+
1297+
returntransformExprRecurse(pstate,result);
1298+
}
1299+
11981300
staticNode*
11991301
transformBoolExpr(ParseState*pstate,BoolExpr*a)
12001302
{

‎src/include/nodes/parsenodes.h

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -232,7 +232,11 @@ typedef enum A_Expr_Kind
232232
AEXPR_DISTINCT,/* IS DISTINCT FROM - name must be "=" */
233233
AEXPR_NULLIF,/* NULLIF - name must be "=" */
234234
AEXPR_OF,/* IS [NOT] OF - name must be "=" or "<>" */
235-
AEXPR_IN/* [NOT] IN - name must be "=" or "<>" */
235+
AEXPR_IN,/* [NOT] IN - name must be "=" or "<>" */
236+
AEXPR_BETWEEN,/* name must be "BETWEEN" */
237+
AEXPR_NOT_BETWEEN,/* name must be "NOT BETWEEN" */
238+
AEXPR_BETWEEN_SYM,/* name must be "BETWEEN SYMMETRIC" */
239+
AEXPR_NOT_BETWEEN_SYM/* name must be "NOT BETWEEN SYMMETRIC" */
236240
}A_Expr_Kind;
237241

238242
typedefstructA_Expr

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