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Indexes for LIKE and ~, !~ operations.

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REL6_4
Bruce Momjian 29 years ago
parent 0308f91cd2
commit 1e7ba76e43
1 changed files with 174 additions and 3 deletions
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  1. 177
      src/backend/parser/gram.y

177
src/backend/parser/gram.y
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 1.60 1997/10/30 16:39:27 thomas Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 1.61 1997/10/31 00:50:39 momjian Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -64,6 +64,7 @@ static Node *makeA_Expr(int oper, char *opname, Node *lexpr, Node *rexpr);
static List *makeConstantList( A_Const *node);
static char *FlattenStringList(List *list);
static char *fmtId(char *rawid);
static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr);
/* old versions of flex define this as a macro */
#if defined(yywrap)
@ -2755,9 +2756,9 @@ a_expr: attr opt_indirection
| '(' a_expr_or_null ')'
{ $$ = $2; }
| a_expr Op a_expr
{ $$ = makeA_Expr(OP, $2, $1, $3); }
{ $$ = makeIndexable($2,$1,$3); }
| a_expr LIKE a_expr
{ $$ = makeA_Expr(OP, "~~", $1, $3); }
{ $$ = makeIndexable("~~", $1, $3); }
| a_expr NOT LIKE a_expr
{ $$ = makeA_Expr(OP, "!~~", $1, $4); }
| Op a_expr
@ -3527,6 +3528,176 @@ static Node *makeA_Expr(int oper, char *opname, Node *lexpr, Node *rexpr)
return (Node *)a;
}
static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr)
{
Node *result = NULL;
/* we do this so indexes can be used */
if (strcmp(opname,"~") == 0)
{
if (nodeTag(rexpr) == T_A_Const &&
((A_Const *)rexpr)->val.type == T_String &&
((A_Const *)rexpr)->val.val.str[0] == '^')
{
A_Const *n = (A_Const *)rexpr;
char *match_least = palloc(strlen(n->val.val.str)+2);
char *match_most = palloc(strlen(n->val.val.str)+2);
int pos, match_pos=0;
/* skip leading ^ */
for (pos = 1; n->val.val.str[pos]; pos++)
{
if (n->val.val.str[pos] == '.' ||
n->val.val.str[pos] == '?' ||
n->val.val.str[pos] == '*' ||
n->val.val.str[pos] == '[' ||
n->val.val.str[pos] == '$')
break;
if (n->val.val.str[pos] == '\\')
pos++;
match_least[match_pos] = n->val.val.str[pos];
match_most[match_pos++] = n->val.val.str[pos];
}
if (match_pos != 0)
{
A_Const *least = makeNode(A_Const);
A_Const *most = makeNode(A_Const);
/* make strings to be used in index use */
match_least[match_pos] = '\0';
match_most[match_pos] = '\377';
match_most[match_pos+1] = '\0';
least->val.type = T_String;
least->val.val.str = match_least;
most->val.type = T_String;
most->val.val.str = match_most;
result = makeA_Expr(AND, NULL,
makeA_Expr(OP, "~", lexpr, rexpr),
makeA_Expr(AND, NULL,
makeA_Expr(OP, ">=", lexpr, (Node *)least),
makeA_Expr(OP, "<=", lexpr, (Node *)most)));
}
}
}
else if (strcmp(opname,"~*") == 0)
{
if (nodeTag(rexpr) == T_A_Const &&
((A_Const *)rexpr)->val.type == T_String &&
((A_Const *)rexpr)->val.val.str[0] == '^')
{
A_Const *n = (A_Const *)rexpr;
char *match_lower_least = palloc(strlen(n->val.val.str)+2);
char *match_lower_most = palloc(strlen(n->val.val.str)+2);
char *match_upper_least = palloc(strlen(n->val.val.str)+2);
char *match_upper_most = palloc(strlen(n->val.val.str)+2);
int pos, match_pos=0;
/* skip leading ^ */
for (pos = 1; n->val.val.str[pos]; pos++)
{
if (n->val.val.str[pos] == '.' ||
n->val.val.str[pos] == '?' ||
n->val.val.str[pos] == '*' ||
n->val.val.str[pos] == '[' ||
n->val.val.str[pos] == '$')
break;
if (n->val.val.str[pos] == '\\')
pos++;
/* If we have punctuation, this works well */
match_lower_least[match_pos] = tolower(n->val.val.str[pos]);
match_lower_most[match_pos] = tolower(n->val.val.str[pos]);
match_upper_least[match_pos] = toupper(n->val.val.str[pos]);
match_upper_most[match_pos++] = toupper(n->val.val.str[pos]);
}
if (match_pos != 0)
{
A_Const *lower_least = makeNode(A_Const);
A_Const *lower_most = makeNode(A_Const);
A_Const *upper_least = makeNode(A_Const);
A_Const *upper_most = makeNode(A_Const);
/* make strings to be used in index use */
match_lower_least[match_pos] = '\0';
match_lower_most[match_pos] = '\377';
match_lower_most[match_pos+1] = '\0';
match_upper_least[match_pos] = '\0';
match_upper_most[match_pos] = '\377';
match_upper_most[match_pos+1] = '\0';
lower_least->val.type = T_String;
lower_least->val.val.str = match_lower_least;
lower_most->val.type = T_String;
lower_most->val.val.str = match_lower_most;
upper_least->val.type = T_String;
upper_least->val.val.str = match_upper_least;
upper_most->val.type = T_String;
upper_most->val.val.str = match_upper_most;
result = makeA_Expr(AND, NULL,
makeA_Expr(OP, "~*", lexpr, rexpr),
makeA_Expr(OR, NULL,
makeA_Expr(AND, NULL,
makeA_Expr(OP, ">=", lexpr, (Node *)lower_least),
makeA_Expr(OP, "<=", lexpr, (Node *)lower_most)),
makeA_Expr(AND, NULL,
makeA_Expr(OP, ">=", lexpr, (Node *)upper_least),
makeA_Expr(OP, "<=", lexpr, (Node *)upper_most))));
}
}
}
else if (strcmp(opname,"~~") == 0)
{
if (nodeTag(rexpr) == T_A_Const &&
((A_Const *)rexpr)->val.type == T_String)
{
A_Const *n = (A_Const *)rexpr;
char *match_least = palloc(strlen(n->val.val.str)+2);
char *match_most = palloc(strlen(n->val.val.str)+2);
int pos, match_pos=0;
for (pos = 0; n->val.val.str[pos]; pos++)
{
if ((n->val.val.str[pos] == '%' &&
n->val.val.str[pos+1] != '%') ||
(n->val.val.str[pos] == '_' &&
n->val.val.str[pos+1] != '_'))
break;
if (n->val.val.str[pos] == '%' ||
n->val.val.str[pos] == '_' ||
n->val.val.str[pos] == '\\')
pos++;
match_least[match_pos] = n->val.val.str[pos];
match_most[match_pos++] = n->val.val.str[pos];
}
if (match_pos != 0)
{
A_Const *least = makeNode(A_Const);
A_Const *most = makeNode(A_Const);
/* make strings to be used in index use */
match_least[match_pos] = '\0';
match_most[match_pos] = '\377';
match_most[match_pos+1] = '\0';
least->val.type = T_String;
least->val.val.str = match_least;
most->val.type = T_String;
most->val.val.str = match_most;
result = makeA_Expr(AND, NULL,
makeA_Expr(OP, "~~", lexpr, rexpr),
makeA_Expr(AND, NULL,
makeA_Expr(OP, ">=", lexpr, (Node *)least),
makeA_Expr(OP, "<=", lexpr, (Node *)most)));
}
}
}
if (result == NULL)
result = makeA_Expr(OP, opname, lexpr, rexpr);
return result;
}
/* xlateSqlType()
* Convert alternate type names to internal Postgres types.
* Do not convert "float", since that is handled elsewhere

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