*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.82 2000/04/12 17:15:19 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.83 2000/04/16 04:41:01 tgl Exp $
*
*-------------------------------------------------------------------------
*/
-#include <ctype.h>
-#include <math.h>
-
#include "postgres.h"
+#include <math.h>
+
#include "access/heapam.h"
#include "access/nbtree.h"
#include "catalog/catname.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_operator.h"
#include "executor/executor.h"
-#include "mb/pg_wchar.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#define is_indexable_operator(clause,opclass,relam,indexkey_on_left) \
(indexable_operator(clause,opclass,relam,indexkey_on_left) != InvalidOid)
-typedef enum
-{
- Prefix_None, Prefix_Partial, Prefix_Exact
-} Prefix_Status;
-
static void match_index_orclauses(RelOptInfo *rel, IndexOptInfo *index,
List *restrictinfo_list);
static List *match_index_orclause(RelOptInfo *rel, IndexOptInfo *index,
IndexOptInfo *index);
static bool match_special_index_operator(Expr *clause, Oid opclass, Oid relam,
bool indexkey_on_left);
-static Prefix_Status like_fixed_prefix(char *patt, char **prefix);
-static Prefix_Status regex_fixed_prefix(char *patt, bool case_insensitive,
- char **prefix);
static List *prefix_quals(Var *leftop, Oid expr_op,
- char *prefix, Prefix_Status pstatus);
-static char *make_greater_string(const char *str, Oid datatype);
+ char *prefix, Pattern_Prefix_Status pstatus);
static Oid find_operator(const char *opname, Oid datatype);
static Datum string_to_datum(const char *str, Oid datatype);
static Const *string_to_const(const char *str, Oid datatype);
-static bool string_lessthan(const char *str1, const char *str2,
- Oid datatype);
/*
Datum constvalue;
char *patt;
char *prefix;
+ char *rest;
/*
* Currently, all known special operators require the indexkey on the
case OID_NAME_LIKE_OP:
/* the right-hand const is type text for all of these */
patt = textout((text *) DatumGetPointer(constvalue));
- isIndexable = like_fixed_prefix(patt, &prefix) != Prefix_None;
+ isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Like,
+ &prefix, &rest) != Pattern_Prefix_None;
if (prefix)
pfree(prefix);
pfree(patt);
case OID_NAME_REGEXEQ_OP:
/* the right-hand const is type text for all of these */
patt = textout((text *) DatumGetPointer(constvalue));
- isIndexable = regex_fixed_prefix(patt, false, &prefix) != Prefix_None;
+ isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Regex,
+ &prefix, &rest) != Pattern_Prefix_None;
if (prefix)
pfree(prefix);
pfree(patt);
case OID_NAME_ICREGEXEQ_OP:
/* the right-hand const is type text for all of these */
patt = textout((text *) DatumGetPointer(constvalue));
- isIndexable = regex_fixed_prefix(patt, true, &prefix) != Prefix_None;
+ isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC,
+ &prefix, &rest) != Pattern_Prefix_None;
if (prefix)
pfree(prefix);
pfree(patt);
Datum constvalue;
char *patt;
char *prefix;
- Prefix_Status pstatus;
+ char *rest;
+ Pattern_Prefix_Status pstatus;
switch (expr_op)
{
/* the right-hand const is type text for all of these */
constvalue = ((Const *) rightop)->constvalue;
patt = textout((text *) DatumGetPointer(constvalue));
- pstatus = like_fixed_prefix(patt, &prefix);
+ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like,
+ &prefix, &rest);
resultquals = nconc(resultquals,
prefix_quals(leftop, expr_op,
prefix, pstatus));
/* the right-hand const is type text for all of these */
constvalue = ((Const *) rightop)->constvalue;
patt = textout((text *) DatumGetPointer(constvalue));
- pstatus = regex_fixed_prefix(patt, false, &prefix);
+ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex,
+ &prefix, &rest);
resultquals = nconc(resultquals,
prefix_quals(leftop, expr_op,
prefix, pstatus));
/* the right-hand const is type text for all of these */
constvalue = ((Const *) rightop)->constvalue;
patt = textout((text *) DatumGetPointer(constvalue));
- pstatus = regex_fixed_prefix(patt, true, &prefix);
+ pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC,
+ &prefix, &rest);
resultquals = nconc(resultquals,
prefix_quals(leftop, expr_op,
prefix, pstatus));
return resultquals;
}
-/*
- * Extract the fixed prefix, if any, for a LIKE pattern.
- * *prefix is set to a palloc'd prefix string,
- * or to NULL if no fixed prefix exists for the pattern.
- * The return value distinguishes no fixed prefix, a partial prefix,
- * or an exact-match-only pattern.
- */
-static Prefix_Status
-like_fixed_prefix(char *patt, char **prefix)
-{
- char *match;
- int pos,
- match_pos;
-
- *prefix = match = palloc(strlen(patt) + 1);
- match_pos = 0;
-
- for (pos = 0; patt[pos]; pos++)
- {
- /* % and _ are wildcard characters in LIKE */
- if (patt[pos] == '%' ||
- patt[pos] == '_')
- break;
- /* Backslash quotes the next character */
- if (patt[pos] == '\\')
- {
- pos++;
- if (patt[pos] == '\0')
- break;
- }
-
- /*
- * NOTE: this code used to think that %% meant a literal %, but
- * textlike() itself does not think that, and the SQL92 spec
- * doesn't say any such thing either.
- */
- match[match_pos++] = patt[pos];
- }
-
- match[match_pos] = '\0';
-
- /* in LIKE, an empty pattern is an exact match! */
- if (patt[pos] == '\0')
- return Prefix_Exact; /* reached end of pattern, so exact */
-
- if (match_pos > 0)
- return Prefix_Partial;
- return Prefix_None;
-}
-
-/*
- * Extract the fixed prefix, if any, for a regex pattern.
- * *prefix is set to a palloc'd prefix string,
- * or to NULL if no fixed prefix exists for the pattern.
- * The return value distinguishes no fixed prefix, a partial prefix,
- * or an exact-match-only pattern.
- */
-static Prefix_Status
-regex_fixed_prefix(char *patt, bool case_insensitive,
- char **prefix)
-{
- char *match;
- int pos,
- match_pos;
-
- *prefix = NULL;
-
- /* Pattern must be anchored left */
- if (patt[0] != '^')
- return Prefix_None;
-
- /* Cannot optimize if unquoted | { } is present in pattern */
- for (pos = 1; patt[pos]; pos++)
- {
- if (patt[pos] == '|' ||
- patt[pos] == '{' ||
- patt[pos] == '}')
- return Prefix_None;
- if (patt[pos] == '\\')
- {
- pos++;
- if (patt[pos] == '\0')
- break;
- }
- }
-
- /* OK, allocate space for pattern */
- *prefix = match = palloc(strlen(patt) + 1);
- match_pos = 0;
-
- /* note start at pos 1 to skip leading ^ */
- for (pos = 1; patt[pos]; pos++)
- {
- if (patt[pos] == '.' ||
- patt[pos] == '?' ||
- patt[pos] == '*' ||
- patt[pos] == '[' ||
- patt[pos] == '$' ||
-
- /*
- * XXX I suspect isalpha() is not an adequately locale-sensitive
- * test for characters that can vary under case folding?
- */
- (case_insensitive && isalpha(patt[pos])))
- break;
- if (patt[pos] == '\\')
- {
- pos++;
- if (patt[pos] == '\0')
- break;
- }
- match[match_pos++] = patt[pos];
- }
-
- match[match_pos] = '\0';
-
- if (patt[pos] == '$' && patt[pos + 1] == '\0')
- return Prefix_Exact; /* pattern specifies exact match */
-
- if (match_pos > 0)
- return Prefix_Partial;
- return Prefix_None;
-}
-
/*
* Given a fixed prefix that all the "leftop" values must have,
* generate suitable indexqual condition(s). expr_op is the original
*/
static List *
prefix_quals(Var *leftop, Oid expr_op,
- char *prefix, Prefix_Status pstatus)
+ char *prefix, Pattern_Prefix_Status pstatus)
{
List *result;
Oid datatype;
Expr *expr;
char *greaterstr;
- Assert(pstatus != Prefix_None);
+ Assert(pstatus != Pattern_Prefix_None);
switch (expr_op)
{
/*
* If we found an exact-match pattern, generate an "=" indexqual.
*/
- if (pstatus == Prefix_Exact)
+ if (pstatus == Pattern_Prefix_Exact)
{
oproid = find_operator("=", datatype);
if (oproid == InvalidOid)
return result;
}
-/*
- * Try to generate a string greater than the given string or any string it is
- * a prefix of. If successful, return a palloc'd string; else return NULL.
- *
- * To work correctly in non-ASCII locales with weird collation orders,
- * we cannot simply increment "foo" to "fop" --- we have to check whether
- * we actually produced a string greater than the given one. If not,
- * increment the righthand byte again and repeat. If we max out the righthand
- * byte, truncate off the last character and start incrementing the next.
- * For example, if "z" were the last character in the sort order, then we
- * could produce "foo" as a string greater than "fonz".
- *
- * This could be rather slow in the worst case, but in most cases we won't
- * have to try more than one or two strings before succeeding.
- *
- * XXX in a sufficiently weird locale, this might produce incorrect results?
- * For example, in German I believe "ss" is treated specially --- if we are
- * given "foos" and return "foot", will this actually be greater than "fooss"?
- */
-static char *
-make_greater_string(const char *str, Oid datatype)
-{
- char *workstr;
- int len;
-
- /*
- * Make a modifiable copy, which will be our return value if
- * successful
- */
- workstr = pstrdup((char *) str);
-
- while ((len = strlen(workstr)) > 0)
- {
- unsigned char *lastchar = (unsigned char *) (workstr + len - 1);
-
- /*
- * Try to generate a larger string by incrementing the last byte.
- */
- while (*lastchar < (unsigned char) 255)
- {
- (*lastchar)++;
- if (string_lessthan(str, workstr, datatype))
- return workstr; /* Success! */
- }
-
- /*
- * Truncate off the last character, which might be more than 1
- * byte in MULTIBYTE case.
- */
-#ifdef MULTIBYTE
- len = pg_mbcliplen((const unsigned char *) workstr, len, len - 1);
- workstr[len] = '\0';
-#else
- *lastchar = '\0';
-#endif
- }
-
- /* Failed... */
- pfree(workstr);
- return NULL;
-}
-
/*
* Handy subroutines for match_special_index_operator() and friends.
*/
return makeConst(datatype, ((datatype == NAMEOID) ? NAMEDATALEN : -1),
conval, false, false, false, false);
}
-
-/*
- * Test whether two strings are "<" according to the rules of the given
- * datatype. We do this the hard way, ie, actually calling the type's
- * "<" operator function, to ensure we get the right result...
- */
-static bool
-string_lessthan(const char *str1, const char *str2, Oid datatype)
-{
- Datum datum1 = string_to_datum(str1, datatype);
- Datum datum2 = string_to_datum(str2, datatype);
- bool result;
-
- switch (datatype)
- {
- case TEXTOID:
- result = text_lt((text *) datum1, (text *) datum2);
- break;
-
- case BPCHAROID:
- result = bpcharlt((char *) datum1, (char *) datum2);
- break;
-
- case VARCHAROID:
- result = varcharlt((char *) datum1, (char *) datum2);
- break;
-
- case NAMEOID:
- result = namelt((NameData *) datum1, (NameData *) datum2);
- break;
-
- default:
- elog(ERROR, "string_lessthan: unexpected datatype %u", datatype);
- result = false;
- break;
- }
-
- pfree(DatumGetPointer(datum1));
- pfree(DatumGetPointer(datum2));
-
- return result;
-}
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.64 2000/04/12 17:15:51 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.65 2000/04/16 04:41:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include <ctype.h>
#include <math.h>
#include "access/heapam.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_statistic.h"
#include "catalog/pg_type.h"
+#include "mb/pg_wchar.h"
#include "optimizer/cost.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
/* default selectivity estimate for inequalities such as "A < b" */
#define DEFAULT_INEQ_SEL (1.0 / 3.0)
-static bool convert_string_to_scalar(char *str, int strlength,
- double *scaleval);
+/* default selectivity estimate for pattern-match operators such as LIKE */
+#define DEFAULT_MATCH_SEL 0.01
+
+static bool convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
+ Datum lobound, Datum hibound, Oid boundstypid,
+ double *scaledlobound, double *scaledhibound);
+static double convert_numeric_to_scalar(Datum value, Oid typid);
+static void convert_string_to_scalar(unsigned char *value,
+ double *scaledvalue,
+ unsigned char *lobound,
+ double *scaledlobound,
+ unsigned char *hibound,
+ double *scaledhibound);
+static double convert_one_string_to_scalar(unsigned char *value,
+ int rangelo, int rangehi);
+static unsigned char * convert_string_datum(Datum value, Oid typid);
+static double convert_timevalue_to_scalar(Datum value, Oid typid);
static void getattproperties(Oid relid, AttrNumber attnum,
Oid *typid,
int *typlen,
Datum *commonval,
Datum *loval,
Datum *hival);
+static Selectivity prefix_selectivity(char *prefix,
+ Oid relid,
+ AttrNumber attno,
+ Oid datatype);
+static Selectivity pattern_selectivity(char *patt, Pattern_Type ptype);
+static bool string_lessthan(const char *str1, const char *str2,
+ Oid datatype);
+static Oid find_operator(const char *opname, Oid datatype);
+static Datum string_to_datum(const char *str, Oid datatype);
/*
*
* Note: this routine is also used to estimate selectivity for some
* operators that are not "=" but have comparable selectivity behavior,
- * such as "~~" (text LIKE). Even for "=" we must keep in mind that
- * the left and right datatypes may differ, so the type of the given
- * constant "value" may be different from the type of the attribute.
+ * such as "~=" (geometric approximate-match). Even for "=", we must
+ * keep in mind that the left and right datatypes may differ, so the type
+ * of the given constant "value" may be different from the type of the
+ * attribute.
*/
float64
eqsel(Oid opid,
{
HeapTuple oprtuple;
Oid ltype,
- rtype;
+ rtype,
+ contype;
Oid typid;
int typlen;
bool typbyval;
elog(ERROR, "scalarltsel: no tuple for operator %u", opid);
ltype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprleft;
rtype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprright;
-
- /* Convert the constant to a uniform comparison scale. */
- if (!convert_to_scalar(value,
- ((flag & SEL_RIGHT) ? rtype : ltype),
- &val))
- {
-
- /*
- * Ideally we'd produce an error here, on the grounds that the
- * given operator shouldn't have scalarltsel registered as its
- * selectivity func unless we can deal with its operand types.
- * But currently, all manner of stuff is invoking scalarltsel,
- * so give a default estimate until that can be fixed.
- */
- *result = DEFAULT_INEQ_SEL;
- return result;
- }
+ contype = (flag & SEL_RIGHT) ? rtype : ltype;
/* Now get info and stats about the attribute */
getattproperties(relid, attno,
return result;
}
- /* Convert the attribute's loval/hival to common scale. */
- if (!convert_to_scalar(loval, typid, &low) ||
- !convert_to_scalar(hival, typid, &high))
+ /* Convert the values to a uniform comparison scale. */
+ if (!convert_to_scalar(value, contype, &val,
+ loval, hival, typid,
+ &low, &high))
{
- /* See above comments... */
+
+ /*
+ * Ideally we'd produce an error here, on the grounds that the
+ * given operator shouldn't have scalarltsel registered as its
+ * selectivity func unless we can deal with its operand types.
+ * But currently, all manner of stuff is invoking scalarltsel,
+ * so give a default estimate until that can be fixed.
+ */
if (!typbyval)
{
pfree(DatumGetPointer(hival));
pfree(DatumGetPointer(loval));
}
-
*result = DEFAULT_INEQ_SEL;
return result;
}
return result;
}
+/*
+ * patternsel - Generic code for pattern-match selectivity.
+ */
+static float64
+patternsel(Oid opid,
+ Pattern_Type ptype,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ float64 result;
+
+ result = (float64) palloc(sizeof(float64data));
+ /* Must have a constant for the pattern, or cannot learn anything */
+ if ((flag & (SEL_CONSTANT | SEL_RIGHT)) != (SEL_CONSTANT | SEL_RIGHT))
+ *result = DEFAULT_MATCH_SEL;
+ else
+ {
+ HeapTuple oprtuple;
+ Oid ltype,
+ rtype;
+ char *patt;
+ Pattern_Prefix_Status pstatus;
+ char *prefix;
+ char *rest;
+
+ /*
+ * Get left and right datatypes of the operator so we know what
+ * type the attribute is.
+ */
+ oprtuple = get_operator_tuple(opid);
+ if (!HeapTupleIsValid(oprtuple))
+ elog(ERROR, "patternsel: no tuple for operator %u", opid);
+ ltype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprleft;
+ rtype = ((Form_pg_operator) GETSTRUCT(oprtuple))->oprright;
+
+ /* the right-hand const is type text for all supported operators */
+ Assert(rtype == TEXTOID);
+ patt = textout((text *) DatumGetPointer(value));
+
+ /* divide pattern into fixed prefix and remainder */
+ pstatus = pattern_fixed_prefix(patt, ptype, &prefix, &rest);
+
+ if (pstatus == Pattern_Prefix_Exact)
+ {
+ /* Pattern specifies an exact match, so pretend operator is '=' */
+ Oid eqopr = find_operator("=", ltype);
+ Datum eqcon;
+
+ if (eqopr == InvalidOid)
+ elog(ERROR, "patternsel: no = operator for type %u", ltype);
+ eqcon = string_to_datum(prefix, ltype);
+ result = eqsel(eqopr, relid, attno, eqcon, SEL_CONSTANT|SEL_RIGHT);
+ pfree(DatumGetPointer(eqcon));
+ }
+ else
+ {
+ /*
+ * Not exact-match pattern. We estimate selectivity of the
+ * fixed prefix and remainder of pattern separately, then
+ * combine the two.
+ */
+ Selectivity prefixsel;
+ Selectivity restsel;
+ Selectivity selec;
+
+ if (pstatus == Pattern_Prefix_Partial)
+ prefixsel = prefix_selectivity(prefix, relid, attno, ltype);
+ else
+ prefixsel = 1.0;
+ restsel = pattern_selectivity(rest, ptype);
+ selec = prefixsel * restsel;
+ /* result should be in range, but make sure... */
+ if (selec < 0.0)
+ selec = 0.0;
+ else if (selec > 1.0)
+ selec = 1.0;
+ *result = (float64data) selec;
+ }
+ if (prefix)
+ pfree(prefix);
+ pfree(patt);
+ }
+ return result;
+}
+
+/*
+ * regexeqsel - Selectivity of regular-expression pattern match.
+ */
+float64
+regexeqsel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ return patternsel(opid, Pattern_Type_Regex, relid, attno, value, flag);
+}
+
+/*
+ * icregexeqsel - Selectivity of case-insensitive regex match.
+ */
+float64
+icregexeqsel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ return patternsel(opid, Pattern_Type_Regex_IC, relid, attno, value, flag);
+}
+
+/*
+ * likesel - Selectivity of LIKE pattern match.
+ */
+float64
+likesel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ return patternsel(opid, Pattern_Type_Like, relid, attno, value, flag);
+}
+
+/*
+ * regexnesel - Selectivity of regular-expression pattern non-match.
+ */
+float64
+regexnesel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ float64 result;
+
+ result = patternsel(opid, Pattern_Type_Regex, relid, attno, value, flag);
+ *result = 1.0 - *result;
+ return result;
+}
+
+/*
+ * icregexnesel - Selectivity of case-insensitive regex non-match.
+ */
+float64
+icregexnesel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ float64 result;
+
+ result = patternsel(opid, Pattern_Type_Regex_IC, relid, attno, value, flag);
+ *result = 1.0 - *result;
+ return result;
+}
+
+/*
+ * nlikesel - Selectivity of LIKE pattern non-match.
+ */
+float64
+nlikesel(Oid opid,
+ Oid relid,
+ AttrNumber attno,
+ Datum value,
+ int32 flag)
+{
+ float64 result;
+
+ result = patternsel(opid, Pattern_Type_Like, relid, attno, value, flag);
+ *result = 1.0 - *result;
+ return result;
+}
+
/*
* eqjoinsel - Join selectivity of "="
*/
return result;
}
+/*
+ * regexeqjoinsel - Join selectivity of regular-expression pattern match.
+ */
+float64
+regexeqjoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = (float64) palloc(sizeof(float64data));
+ *result = DEFAULT_MATCH_SEL;
+ return result;
+}
+
+/*
+ * icregexeqjoinsel - Join selectivity of case-insensitive regex match.
+ */
+float64
+icregexeqjoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = (float64) palloc(sizeof(float64data));
+ *result = DEFAULT_MATCH_SEL;
+ return result;
+}
+
+/*
+ * likejoinsel - Join selectivity of LIKE pattern match.
+ */
+float64
+likejoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = (float64) palloc(sizeof(float64data));
+ *result = DEFAULT_MATCH_SEL;
+ return result;
+}
+
+/*
+ * regexnejoinsel - Join selectivity of regex non-match.
+ */
+float64
+regexnejoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = regexeqjoinsel(opid, relid1, attno1, relid2, attno2);
+ *result = 1.0 - *result;
+ return result;
+}
+
+/*
+ * icregexnejoinsel - Join selectivity of case-insensitive regex non-match.
+ */
+float64
+icregexnejoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = icregexeqjoinsel(opid, relid1, attno1, relid2, attno2);
+ *result = 1.0 - *result;
+ return result;
+}
+
+/*
+ * nlikejoinsel - Join selectivity of LIKE pattern non-match.
+ */
+float64
+nlikejoinsel(Oid opid,
+ Oid relid1,
+ AttrNumber attno1,
+ Oid relid2,
+ AttrNumber attno2)
+{
+ float64 result;
+
+ result = likejoinsel(opid, relid1, attno1, relid2, attno2);
+ *result = 1.0 - *result;
+ return result;
+}
+
+
/*
* convert_to_scalar
- * Convert a non-NULL value of the indicated type to the comparison
+ * Convert non-NULL values of the indicated types to the comparison
* scale needed by scalarltsel()/scalargtsel().
* Returns "true" if successful.
*
* "double" values.
*
* String datatypes are converted by convert_string_to_scalar(),
- * which is explained below.
+ * which is explained below. The reason why this routine deals with
+ * three values at a time, not just one, is that we need it for strings.
*
* The several datatypes representing absolute times are all converted
* to Timestamp, which is actually a double, and then we just use that
* The several datatypes representing relative times (intervals) are all
* converted to measurements expressed in seconds.
*/
-bool
-convert_to_scalar(Datum value, Oid typid,
- double *scaleval)
+static bool
+convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
+ Datum lobound, Datum hibound, Oid boundstypid,
+ double *scaledlobound, double *scaledhibound)
{
- switch (typid)
+ switch (valuetypid)
{
- /*
- * Built-in numeric types
- */
- case BOOLOID:
- *scaleval = (double) DatumGetUInt8(value);
- return true;
+ /*
+ * Built-in numeric types
+ */
+ case BOOLOID:
case INT2OID:
- *scaleval = (double) DatumGetInt16(value);
- return true;
case INT4OID:
- *scaleval = (double) DatumGetInt32(value);
- return true;
case INT8OID:
- *scaleval = (double) (*i8tod((int64 *) DatumGetPointer(value)));
- return true;
case FLOAT4OID:
- *scaleval = (double) (*DatumGetFloat32(value));
- return true;
case FLOAT8OID:
- *scaleval = (double) (*DatumGetFloat64(value));
- return true;
case NUMERICOID:
- *scaleval = (double) (*numeric_float8((Numeric) DatumGetPointer(value)));
- return true;
case OIDOID:
case REGPROCOID:
- /* we can treat OIDs as integers... */
- *scaleval = (double) DatumGetObjectId(value);
+ *scaledvalue = convert_numeric_to_scalar(value, valuetypid);
+ *scaledlobound = convert_numeric_to_scalar(lobound, boundstypid);
+ *scaledhibound = convert_numeric_to_scalar(hibound, boundstypid);
return true;
- /*
- * Built-in string types
- */
+ /*
+ * Built-in string types
+ */
case CHAROID:
- {
- char ch = DatumGetChar(value);
-
- return convert_string_to_scalar(&ch, 1, scaleval);
- }
case BPCHAROID:
case VARCHAROID:
case TEXTOID:
- {
- char *str = (char *) VARDATA(DatumGetPointer(value));
- int strlength = VARSIZE(DatumGetPointer(value)) - VARHDRSZ;
-
- return convert_string_to_scalar(str, strlength, scaleval);
- }
case NAMEOID:
- {
- NameData *nm = (NameData *) DatumGetPointer(value);
-
- return convert_string_to_scalar(NameStr(*nm), strlen(NameStr(*nm)),
- scaleval);
- }
+ {
+ unsigned char *valstr = convert_string_datum(value, valuetypid);
+ unsigned char *lostr = convert_string_datum(lobound, boundstypid);
+ unsigned char *histr = convert_string_datum(hibound, boundstypid);
+
+ convert_string_to_scalar(valstr, scaledvalue,
+ lostr, scaledlobound,
+ histr, scaledhibound);
+ pfree(valstr);
+ pfree(lostr);
+ pfree(histr);
+ return true;
+ }
- /*
- * Built-in absolute-time types
- */
+ /*
+ * Built-in time types
+ */
case TIMESTAMPOID:
- *scaleval = *((Timestamp *) DatumGetPointer(value));
- return true;
case ABSTIMEOID:
- *scaleval = *abstime_timestamp(value);
- return true;
case DATEOID:
- *scaleval = *date_timestamp(value);
- return true;
-
- /*
- * Built-in relative-time types
- */
case INTERVALOID:
- {
- Interval *interval = (Interval *) DatumGetPointer(value);
-
- /*
- * Convert the month part of Interval to days using
- * assumed average month length of 365.25/12.0 days. Not
- * too accurate, but plenty good enough for our purposes.
- */
- *scaleval = interval->time +
- interval->month * (365.25 / 12.0 * 24.0 * 60.0 * 60.0);
- return true;
- }
case RELTIMEOID:
- *scaleval = (RelativeTime) DatumGetInt32(value);
- return true;
case TINTERVALOID:
- {
- TimeInterval interval = (TimeInterval) DatumGetPointer(value);
-
- if (interval->status != 0)
- {
- *scaleval = interval->data[1] - interval->data[0];
- return true;
- }
- break;
- }
case TIMEOID:
- *scaleval = *((TimeADT *) DatumGetPointer(value));
+ *scaledvalue = convert_timevalue_to_scalar(value, valuetypid);
+ *scaledlobound = convert_timevalue_to_scalar(lobound, boundstypid);
+ *scaledhibound = convert_timevalue_to_scalar(hibound, boundstypid);
return true;
-
- default:
- {
-
- /*
- * See whether there is a registered type-conversion
- * function, namely a procedure named "float8" with the
- * right signature. If so, assume we can convert the value
- * to the numeric scale.
- *
- * NOTE: there are no such procedures in the standard
- * distribution, except with argument types that we
- * already dealt with above. This code is just here as an
- * escape for user-defined types.
- */
- Oid oid_array[FUNC_MAX_ARGS];
- HeapTuple ftup;
-
- MemSet(oid_array, 0, FUNC_MAX_ARGS * sizeof(Oid));
- oid_array[0] = typid;
- ftup = SearchSysCacheTuple(PROCNAME,
- PointerGetDatum("float8"),
- Int32GetDatum(1),
- PointerGetDatum(oid_array),
- 0);
- if (HeapTupleIsValid(ftup) &&
- ((Form_pg_proc) GETSTRUCT(ftup))->prorettype == FLOAT8OID)
- {
- RegProcedure convertproc = (RegProcedure) ftup->t_data->t_oid;
- Datum converted = (Datum) fmgr(convertproc, value);
-
- *scaleval = (double) (*DatumGetFloat64(converted));
- return true;
- }
- break;
- }
}
/* Don't know how to convert */
return false;
}
+/*
+ * Do convert_to_scalar()'s work for any numeric data type.
+ */
+static double
+convert_numeric_to_scalar(Datum value, Oid typid)
+{
+ switch (typid)
+ {
+ case BOOLOID:
+ return (double) DatumGetUInt8(value);
+ case INT2OID:
+ return (double) DatumGetInt16(value);
+ case INT4OID:
+ return (double) DatumGetInt32(value);
+ case INT8OID:
+ return (double) (*i8tod((int64 *) DatumGetPointer(value)));
+ case FLOAT4OID:
+ return (double) (*DatumGetFloat32(value));
+ case FLOAT8OID:
+ return (double) (*DatumGetFloat64(value));
+ case NUMERICOID:
+ return (double) (*numeric_float8((Numeric) DatumGetPointer(value)));
+ case OIDOID:
+ case REGPROCOID:
+ /* we can treat OIDs as integers... */
+ return (double) DatumGetObjectId(value);
+ }
+ /* Can't get here unless someone tries to use scalarltsel/scalargtsel
+ * on an operator with one numeric and one non-numeric operand.
+ */
+ elog(ERROR, "convert_numeric_to_scalar: unsupported type %u", typid);
+ return 0;
+}
+
/*
* Do convert_to_scalar()'s work for any character-string data type.
*
- * String datatypes are converted to a scale that ranges from 0 to 1, where
- * we visualize the bytes of the string as fractional base-256 digits.
- * It's sufficient to consider the first few bytes, since double has only
- * limited precision (and we can't expect huge accuracy in our selectivity
- * predictions anyway!)
+ * String datatypes are converted to a scale that ranges from 0 to 1,
+ * where we visualize the bytes of the string as fractional digits.
*
- * If USE_LOCALE is defined, we must pass the string through strxfrm()
- * before doing the computation, so as to generate correct locale-specific
- * results.
+ * We do not want the base to be 256, however, since that tends to
+ * generate inflated selectivity estimates; few databases will have
+ * occurrences of all 256 possible byte values at each position.
+ * Instead, use the smallest and largest byte values seen in the bounds
+ * as the estimated range for each byte, after some fudging to deal with
+ * the fact that we probably aren't going to see the full range that way.
+ *
+ * An additional refinement is that we discard any common prefix of the
+ * three strings before computing the scaled values. This allows us to
+ * "zoom in" when we encounter a narrow data range. An example is a phone
+ * number database where all the values begin with the same area code.
*/
-static bool
-convert_string_to_scalar(char *str, int strlength,
- double *scaleval)
+static void
+convert_string_to_scalar(unsigned char *value,
+ double *scaledvalue,
+ unsigned char *lobound,
+ double *scaledlobound,
+ unsigned char *hibound,
+ double *scaledhibound)
{
+ int rangelo,
+ rangehi;
unsigned char *sptr;
- int slen;
+ rangelo = rangehi = hibound[0];
+ for (sptr = lobound; *sptr; sptr++)
+ {
+ if (rangelo > *sptr)
+ rangelo = *sptr;
+ if (rangehi < *sptr)
+ rangehi = *sptr;
+ }
+ for (sptr = hibound; *sptr; sptr++)
+ {
+ if (rangelo > *sptr)
+ rangelo = *sptr;
+ if (rangehi < *sptr)
+ rangehi = *sptr;
+ }
+ /* If range includes any upper-case ASCII chars, make it include all */
+ if (rangelo <= 'Z' && rangehi >= 'A')
+ {
+ if (rangelo > 'A')
+ rangelo = 'A';
+ if (rangehi < 'Z')
+ rangehi = 'Z';
+ }
+ /* Ditto lower-case */
+ if (rangelo <= 'z' && rangehi >= 'a')
+ {
+ if (rangelo > 'a')
+ rangelo = 'a';
+ if (rangehi < 'z')
+ rangehi = 'z';
+ }
+ /* Ditto digits */
+ if (rangelo <= '9' && rangehi >= '0')
+ {
+ if (rangelo > '0')
+ rangelo = '0';
+ if (rangehi < '9')
+ rangehi = '9';
+ }
+ /* If range includes less than 10 chars, assume we have not got enough
+ * data, and make it include regular ASCII set.
+ */
+ if (rangehi - rangelo < 9)
+ {
+ rangelo = ' ';
+ rangehi = 127;
+ }
+
+ /*
+ * Now strip any common prefix of the three strings.
+ */
+ while (*lobound)
+ {
+ if (*lobound != *hibound || *lobound != *value)
+ break;
+ lobound++, hibound++, value++;
+ }
+
+ /*
+ * Now we can do the conversions.
+ */
+ *scaledvalue = convert_one_string_to_scalar(value, rangelo, rangehi);
+ *scaledlobound = convert_one_string_to_scalar(lobound, rangelo, rangehi);
+ *scaledhibound = convert_one_string_to_scalar(hibound, rangelo, rangehi);
+}
+
+static double
+convert_one_string_to_scalar(unsigned char *value, int rangelo, int rangehi)
+{
+ int slen = strlen((char *) value);
+ double num,
+ denom,
+ base;
+
+ if (slen <= 0)
+ return 0.0; /* empty string has scalar value 0 */
+
+ /* Since base is at least 10, need not consider more than about 20 chars */
+ if (slen > 20)
+ slen = 20;
+
+ /* Convert initial characters to fraction */
+ base = rangehi - rangelo + 1;
+ num = 0.0;
+ denom = base;
+ while (slen-- > 0)
+ {
+ int ch = *value++;
+
+ if (ch < rangelo)
+ ch = rangelo-1;
+ else if (ch > rangehi)
+ ch = rangehi+1;
+ num += ((double) (ch - rangelo)) / denom;
+ denom *= base;
+ }
+
+ return num;
+}
+
+/*
+ * Convert a string-type Datum into a palloc'd, null-terminated string.
+ *
+ * If USE_LOCALE is defined, we must pass the string through strxfrm()
+ * before continuing, so as to generate correct locale-specific results.
+ */
+static unsigned char *
+convert_string_datum(Datum value, Oid typid)
+{
+ char *val;
#ifdef USE_LOCALE
- char *rawstr;
char *xfrmstr;
size_t xfrmsize;
size_t xfrmlen;
-
#endif
- double num,
- denom;
- if (strlength <= 0)
+ switch (typid)
{
- *scaleval = 0; /* empty string has scalar value 0 */
- return true;
+ case CHAROID:
+ val = (char *) palloc(2);
+ val[0] = DatumGetChar(value);
+ val[1] = '\0';
+ break;
+ case BPCHAROID:
+ case VARCHAROID:
+ case TEXTOID:
+ {
+ char *str = (char *) VARDATA(DatumGetPointer(value));
+ int strlength = VARSIZE(DatumGetPointer(value)) - VARHDRSZ;
+
+ val = (char *) palloc(strlength+1);
+ memcpy(val, str, strlength);
+ val[strlength] = '\0';
+ break;
+ }
+ case NAMEOID:
+ {
+ NameData *nm = (NameData *) DatumGetPointer(value);
+
+ val = pstrdup(NameStr(*nm));
+ break;
+ }
+ default:
+ /* Can't get here unless someone tries to use scalarltsel
+ * on an operator with one string and one non-string operand.
+ */
+ elog(ERROR, "convert_string_datum: unsupported type %u", typid);
+ return NULL;
}
#ifdef USE_LOCALE
- /* Need a null-terminated string to pass to strxfrm() */
- rawstr = (char *) palloc(strlength + 1);
- memcpy(rawstr, str, strlength);
- rawstr[strlength] = '\0';
-
- /* Guess that transformed string is not much bigger */
- xfrmsize = strlength + 32; /* arbitrary pad value here... */
+ /* Guess that transformed string is not much bigger than original */
+ xfrmsize = strlen(val) + 32; /* arbitrary pad value here... */
xfrmstr = (char *) palloc(xfrmsize);
- xfrmlen = strxfrm(xfrmstr, rawstr, xfrmsize);
+ xfrmlen = strxfrm(xfrmstr, val, xfrmsize);
if (xfrmlen >= xfrmsize)
{
/* Oops, didn't make it */
pfree(xfrmstr);
xfrmstr = (char *) palloc(xfrmlen + 1);
- xfrmlen = strxfrm(xfrmstr, rawstr, xfrmlen + 1);
+ xfrmlen = strxfrm(xfrmstr, val, xfrmlen + 1);
}
- pfree(rawstr);
-
- sptr = (unsigned char *) xfrmstr;
- slen = xfrmlen;
-#else
- sptr = (unsigned char *) str;
- slen = strlength;
+ pfree(val);
+ val = xfrmstr;
#endif
- /* No need to consider more than about 8 bytes (sizeof double) */
- if (slen > 8)
- slen = 8;
+ return (unsigned char *) val;
+}
- /* Convert initial characters to fraction */
- num = 0.0;
- denom = 256.0;
- while (slen-- > 0)
+/*
+ * Do convert_to_scalar()'s work for any timevalue data type.
+ */
+static double
+convert_timevalue_to_scalar(Datum value, Oid typid)
+{
+ switch (typid)
{
- num += ((double) (*sptr++)) / denom;
- denom *= 256.0;
- }
+ case TIMESTAMPOID:
+ return *((Timestamp *) DatumGetPointer(value));
+ case ABSTIMEOID:
+ return *abstime_timestamp(value);
+ case DATEOID:
+ return *date_timestamp(value);
+ case INTERVALOID:
+ {
+ Interval *interval = (Interval *) DatumGetPointer(value);
-#ifdef USE_LOCALE
- pfree(xfrmstr);
-#endif
+ /*
+ * Convert the month part of Interval to days using
+ * assumed average month length of 365.25/12.0 days. Not
+ * too accurate, but plenty good enough for our purposes.
+ */
+ return interval->time +
+ interval->month * (365.25 / 12.0 * 24.0 * 60.0 * 60.0);
+ }
+ case RELTIMEOID:
+ return (RelativeTime) DatumGetInt32(value);
+ case TINTERVALOID:
+ {
+ TimeInterval interval = (TimeInterval) DatumGetPointer(value);
- *scaleval = num;
- return true;
+ if (interval->status != 0)
+ return interval->data[1] - interval->data[0];
+ return 0; /* for lack of a better idea */
+ }
+ case TIMEOID:
+ return *((TimeADT *) DatumGetPointer(value));
+ }
+ /* Can't get here unless someone tries to use scalarltsel/scalargtsel
+ * on an operator with one timevalue and one non-timevalue operand.
+ */
+ elog(ERROR, "convert_timevalue_to_scalar: unsupported type %u", typid);
+ return 0;
}
return true;
}
+/*-------------------------------------------------------------------------
+ *
+ * Pattern analysis functions
+ *
+ * These routines support analysis of LIKE and regular-expression patterns
+ * by the planner/optimizer. It's important that they agree with the
+ * regular-expression code in backend/regex/ and the LIKE code in
+ * backend/utils/adt/like.c.
+ *
+ * Note that the prefix-analysis functions are called from
+ * backend/optimizer/path/indxpath.c as well as from routines in this file.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * Extract the fixed prefix, if any, for a pattern.
+ * *prefix is set to a palloc'd prefix string,
+ * or to NULL if no fixed prefix exists for the pattern.
+ * *rest is set to point to the remainder of the pattern after the
+ * portion describing the fixed prefix.
+ * The return value distinguishes no fixed prefix, a partial prefix,
+ * or an exact-match-only pattern.
+ */
+
+static Pattern_Prefix_Status
+like_fixed_prefix(char *patt, char **prefix, char **rest)
+{
+ char *match;
+ int pos,
+ match_pos;
+
+ *prefix = match = palloc(strlen(patt) + 1);
+ match_pos = 0;
+
+ for (pos = 0; patt[pos]; pos++)
+ {
+ /* % and _ are wildcard characters in LIKE */
+ if (patt[pos] == '%' ||
+ patt[pos] == '_')
+ break;
+ /* Backslash quotes the next character */
+ if (patt[pos] == '\\')
+ {
+ pos++;
+ if (patt[pos] == '\0')
+ break;
+ }
+
+ /*
+ * NOTE: this code used to think that %% meant a literal %, but
+ * textlike() itself does not think that, and the SQL92 spec
+ * doesn't say any such thing either.
+ */
+ match[match_pos++] = patt[pos];
+ }
+
+ match[match_pos] = '\0';
+ *rest = &patt[pos];
+
+ /* in LIKE, an empty pattern is an exact match! */
+ if (patt[pos] == '\0')
+ return Pattern_Prefix_Exact; /* reached end of pattern, so exact */
+
+ if (match_pos > 0)
+ return Pattern_Prefix_Partial;
+
+ pfree(match);
+ *prefix = NULL;
+ return Pattern_Prefix_None;
+}
+
+static Pattern_Prefix_Status
+regex_fixed_prefix(char *patt, bool case_insensitive,
+ char **prefix, char **rest)
+{
+ char *match;
+ int pos,
+ match_pos,
+ paren_depth;
+
+ /* Pattern must be anchored left */
+ if (patt[0] != '^')
+ {
+ *prefix = NULL;
+ *rest = patt;
+ return Pattern_Prefix_None;
+ }
+
+ /* If unquoted | is present at paren level 0 in pattern, then there
+ * are multiple alternatives for the start of the string.
+ */
+ paren_depth = 0;
+ for (pos = 1; patt[pos]; pos++)
+ {
+ if (patt[pos] == '|' && paren_depth == 0)
+ {
+ *prefix = NULL;
+ *rest = patt;
+ return Pattern_Prefix_None;
+ }
+ else if (patt[pos] == '(')
+ paren_depth++;
+ else if (patt[pos] == ')' && paren_depth > 0)
+ paren_depth--;
+ else if (patt[pos] == '\\')
+ {
+ /* backslash quotes the next character */
+ pos++;
+ if (patt[pos] == '\0')
+ break;
+ }
+ }
+
+ /* OK, allocate space for pattern */
+ *prefix = match = palloc(strlen(patt) + 1);
+ match_pos = 0;
+
+ /* note start at pos 1 to skip leading ^ */
+ for (pos = 1; patt[pos]; pos++)
+ {
+ /*
+ * Check for characters that indicate multiple possible matches here.
+ * XXX I suspect isalpha() is not an adequately locale-sensitive
+ * test for characters that can vary under case folding?
+ */
+ if (patt[pos] == '.' ||
+ patt[pos] == '(' ||
+ patt[pos] == '[' ||
+ patt[pos] == '$' ||
+ (case_insensitive && isalpha(patt[pos])))
+ break;
+ /*
+ * Check for quantifiers. Except for +, this means the preceding
+ * character is optional, so we must remove it from the prefix too!
+ */
+ if (patt[pos] == '*' ||
+ patt[pos] == '?' ||
+ patt[pos] == '{')
+ {
+ if (match_pos > 0)
+ match_pos--;
+ pos--;
+ break;
+ }
+ if (patt[pos] == '+')
+ {
+ pos--;
+ break;
+ }
+ if (patt[pos] == '\\')
+ {
+ /* backslash quotes the next character */
+ pos++;
+ if (patt[pos] == '\0')
+ break;
+ }
+ match[match_pos++] = patt[pos];
+ }
+
+ match[match_pos] = '\0';
+ *rest = &patt[pos];
+
+ if (patt[pos] == '$' && patt[pos + 1] == '\0')
+ {
+ *rest = &patt[pos + 1];
+ return Pattern_Prefix_Exact; /* pattern specifies exact match */
+ }
+
+ if (match_pos > 0)
+ return Pattern_Prefix_Partial;
+
+ pfree(match);
+ *prefix = NULL;
+ return Pattern_Prefix_None;
+}
+
+Pattern_Prefix_Status
+pattern_fixed_prefix(char *patt, Pattern_Type ptype,
+ char **prefix, char **rest)
+{
+ Pattern_Prefix_Status result;
+
+ switch (ptype)
+ {
+ case Pattern_Type_Like:
+ result = like_fixed_prefix(patt, prefix, rest);
+ break;
+ case Pattern_Type_Regex:
+ result = regex_fixed_prefix(patt, false, prefix, rest);
+ break;
+ case Pattern_Type_Regex_IC:
+ result = regex_fixed_prefix(patt, true, prefix, rest);
+ break;
+ default:
+ elog(ERROR, "pattern_fixed_prefix: bogus ptype");
+ result = Pattern_Prefix_None; /* keep compiler quiet */
+ break;
+ }
+ return result;
+}
+
+/*
+ * Estimate the selectivity of a fixed prefix for a pattern match.
+ *
+ * A fixed prefix "foo" is estimated as the selectivity of the expression
+ * "var >= 'foo' AND var < 'fop'" (see also indxqual.c).
+ */
+static Selectivity
+prefix_selectivity(char *prefix,
+ Oid relid,
+ AttrNumber attno,
+ Oid datatype)
+{
+ Selectivity prefixsel;
+ Oid cmpopr;
+ Datum prefixcon;
+ char *greaterstr;
+
+ cmpopr = find_operator(">=", datatype);
+ if (cmpopr == InvalidOid)
+ elog(ERROR, "prefix_selectivity: no >= operator for type %u",
+ datatype);
+ prefixcon = string_to_datum(prefix, datatype);
+ /* Assume scalargtsel is appropriate for all supported types */
+ prefixsel = * scalargtsel(cmpopr, relid, attno,
+ prefixcon, SEL_CONSTANT|SEL_RIGHT);
+ pfree(DatumGetPointer(prefixcon));
+
+ /*
+ * If we can create a string larger than the prefix,
+ * say "x < greaterstr".
+ */
+ greaterstr = make_greater_string(prefix, datatype);
+ if (greaterstr)
+ {
+ Selectivity topsel;
+
+ cmpopr = find_operator("<", datatype);
+ if (cmpopr == InvalidOid)
+ elog(ERROR, "prefix_selectivity: no < operator for type %u",
+ datatype);
+ prefixcon = string_to_datum(greaterstr, datatype);
+ /* Assume scalarltsel is appropriate for all supported types */
+ topsel = * scalarltsel(cmpopr, relid, attno,
+ prefixcon, SEL_CONSTANT|SEL_RIGHT);
+ pfree(DatumGetPointer(prefixcon));
+ pfree(greaterstr);
+
+ /*
+ * Merge the two selectivities in the same way as for
+ * a range query (see clauselist_selectivity()).
+ */
+ prefixsel = topsel + prefixsel - 1.0;
+
+ /*
+ * A zero or slightly negative prefixsel should be converted into a
+ * small positive value; we probably are dealing with a very
+ * tight range and got a bogus result due to roundoff errors.
+ * However, if prefixsel is very negative, then we probably have
+ * default selectivity estimates on one or both sides of the
+ * range. In that case, insert a not-so-wildly-optimistic
+ * default estimate.
+ */
+ if (prefixsel <= 0.0)
+ {
+ if (prefixsel < -0.01)
+ {
+
+ /*
+ * No data available --- use a default estimate that
+ * is small, but not real small.
+ */
+ prefixsel = 0.01;
+ }
+ else
+ {
+
+ /*
+ * It's just roundoff error; use a small positive value
+ */
+ prefixsel = 1.0e-10;
+ }
+ }
+ }
+
+ return prefixsel;
+}
+
+
+/*
+ * Estimate the selectivity of a pattern of the specified type.
+ * Note that any fixed prefix of the pattern will have been removed already.
+ *
+ * For now, we use a very simplistic approach: fixed characters reduce the
+ * selectivity a good deal, character ranges reduce it a little,
+ * wildcards (such as % for LIKE or .* for regex) increase it.
+ */
+
+#define FIXED_CHAR_SEL 0.04 /* about 1/25 */
+#define CHAR_RANGE_SEL 0.25
+#define ANY_CHAR_SEL 0.9 /* not 1, since it won't match end-of-string */
+#define FULL_WILDCARD_SEL 5.0
+#define PARTIAL_WILDCARD_SEL 2.0
+
+static Selectivity
+like_selectivity(char *patt)
+{
+ Selectivity sel = 1.0;
+ int pos;
+
+ /* Skip any leading %; it's already factored into initial sel */
+ pos = (*patt == '%') ? 1 : 0;
+ for (; patt[pos]; pos++)
+ {
+ /* % and _ are wildcard characters in LIKE */
+ if (patt[pos] == '%')
+ sel *= FULL_WILDCARD_SEL;
+ else if (patt[pos] == '_')
+ sel *= ANY_CHAR_SEL;
+ else if (patt[pos] == '\\')
+ {
+ /* Backslash quotes the next character */
+ pos++;
+ if (patt[pos] == '\0')
+ break;
+ sel *= FIXED_CHAR_SEL;
+ }
+ else
+ sel *= FIXED_CHAR_SEL;
+ }
+ /* Could get sel > 1 if multiple wildcards */
+ if (sel > 1.0)
+ sel = 1.0;
+ return sel;
+}
+
+static Selectivity
+regex_selectivity_sub(char *patt, int pattlen, bool case_insensitive)
+{
+ Selectivity sel = 1.0;
+ int paren_depth = 0;
+ int paren_pos = 0; /* dummy init to keep compiler quiet */
+ int pos;
+
+ for (pos = 0; pos < pattlen; pos++)
+ {
+ if (patt[pos] == '(')
+ {
+ if (paren_depth == 0)
+ paren_pos = pos; /* remember start of parenthesized item */
+ paren_depth++;
+ }
+ else if (patt[pos] == ')' && paren_depth > 0)
+ {
+ paren_depth--;
+ if (paren_depth == 0)
+ sel *= regex_selectivity_sub(patt + (paren_pos + 1),
+ pos - (paren_pos + 1),
+ case_insensitive);
+ }
+ else if (patt[pos] == '|' && paren_depth == 0)
+ {
+ /*
+ * If unquoted | is present at paren level 0 in pattern,
+ * we have multiple alternatives; sum their probabilities.
+ */
+ sel += regex_selectivity_sub(patt + (pos + 1),
+ pattlen - (pos + 1),
+ case_insensitive);
+ break; /* rest of pattern is now processed */
+ }
+ else if (patt[pos] == '[')
+ {
+ bool negclass = false;
+
+ if (patt[++pos] == '^')
+ {
+ negclass = true;
+ pos++;
+ }
+ if (patt[pos] == ']') /* ']' at start of class is not special */
+ pos++;
+ while (pos < pattlen && patt[pos] != ']')
+ pos++;
+ if (paren_depth == 0)
+ sel *= (negclass ? (1.0-CHAR_RANGE_SEL) : CHAR_RANGE_SEL);
+ }
+ else if (patt[pos] == '.')
+ {
+ if (paren_depth == 0)
+ sel *= ANY_CHAR_SEL;
+ }
+ else if (patt[pos] == '*' ||
+ patt[pos] == '?' ||
+ patt[pos] == '+')
+ {
+ /* Ought to be smarter about quantifiers... */
+ if (paren_depth == 0)
+ sel *= PARTIAL_WILDCARD_SEL;
+ }
+ else if (patt[pos] == '{')
+ {
+ while (pos < pattlen && patt[pos] != '}')
+ pos++;
+ if (paren_depth == 0)
+ sel *= PARTIAL_WILDCARD_SEL;
+ }
+ else if (patt[pos] == '\\')
+ {
+ /* backslash quotes the next character */
+ pos++;
+ if (pos >= pattlen)
+ break;
+ if (paren_depth == 0)
+ sel *= FIXED_CHAR_SEL;
+ }
+ else
+ {
+ if (paren_depth == 0)
+ sel *= FIXED_CHAR_SEL;
+ }
+ }
+ /* Could get sel > 1 if multiple wildcards */
+ if (sel > 1.0)
+ sel = 1.0;
+ return sel;
+}
+
+static Selectivity
+regex_selectivity(char *patt, bool case_insensitive)
+{
+ Selectivity sel;
+ int pattlen = strlen(patt);
+
+ /* If patt doesn't end with $, consider it to have a trailing wildcard */
+ if (pattlen > 0 && patt[pattlen-1] == '$' &&
+ (pattlen == 1 || patt[pattlen-2] != '\\'))
+ {
+ /* has trailing $ */
+ sel = regex_selectivity_sub(patt, pattlen-1, case_insensitive);
+ }
+ else
+ {
+ /* no trailing $ */
+ sel = regex_selectivity_sub(patt, pattlen, case_insensitive);
+ sel *= FULL_WILDCARD_SEL;
+ if (sel > 1.0)
+ sel = 1.0;
+ }
+ return sel;
+}
+
+static Selectivity
+pattern_selectivity(char *patt, Pattern_Type ptype)
+{
+ Selectivity result;
+
+ switch (ptype)
+ {
+ case Pattern_Type_Like:
+ result = like_selectivity(patt);
+ break;
+ case Pattern_Type_Regex:
+ result = regex_selectivity(patt, false);
+ break;
+ case Pattern_Type_Regex_IC:
+ result = regex_selectivity(patt, true);
+ break;
+ default:
+ elog(ERROR, "pattern_selectivity: bogus ptype");
+ result = 1.0; /* keep compiler quiet */
+ break;
+ }
+ return result;
+}
+
+
+/*
+ * Try to generate a string greater than the given string or any string it is
+ * a prefix of. If successful, return a palloc'd string; else return NULL.
+ *
+ * To work correctly in non-ASCII locales with weird collation orders,
+ * we cannot simply increment "foo" to "fop" --- we have to check whether
+ * we actually produced a string greater than the given one. If not,
+ * increment the righthand byte again and repeat. If we max out the righthand
+ * byte, truncate off the last character and start incrementing the next.
+ * For example, if "z" were the last character in the sort order, then we
+ * could produce "foo" as a string greater than "fonz".
+ *
+ * This could be rather slow in the worst case, but in most cases we won't
+ * have to try more than one or two strings before succeeding.
+ *
+ * XXX in a sufficiently weird locale, this might produce incorrect results?
+ * For example, in German I believe "ss" is treated specially --- if we are
+ * given "foos" and return "foot", will this actually be greater than "fooss"?
+ */
+char *
+make_greater_string(const char *str, Oid datatype)
+{
+ char *workstr;
+ int len;
+
+ /*
+ * Make a modifiable copy, which will be our return value if
+ * successful
+ */
+ workstr = pstrdup((char *) str);
+
+ while ((len = strlen(workstr)) > 0)
+ {
+ unsigned char *lastchar = (unsigned char *) (workstr + len - 1);
+
+ /*
+ * Try to generate a larger string by incrementing the last byte.
+ */
+ while (*lastchar < (unsigned char) 255)
+ {
+ (*lastchar)++;
+ if (string_lessthan(str, workstr, datatype))
+ return workstr; /* Success! */
+ }
+
+ /*
+ * Truncate off the last character, which might be more than 1
+ * byte in MULTIBYTE case.
+ */
+#ifdef MULTIBYTE
+ len = pg_mbcliplen((const unsigned char *) workstr, len, len - 1);
+ workstr[len] = '\0';
+#else
+ *lastchar = '\0';
+#endif
+ }
+
+ /* Failed... */
+ pfree(workstr);
+ return NULL;
+}
+
+/*
+ * Test whether two strings are "<" according to the rules of the given
+ * datatype. We do this the hard way, ie, actually calling the type's
+ * "<" operator function, to ensure we get the right result...
+ */
+static bool
+string_lessthan(const char *str1, const char *str2, Oid datatype)
+{
+ Datum datum1 = string_to_datum(str1, datatype);
+ Datum datum2 = string_to_datum(str2, datatype);
+ bool result;
+
+ switch (datatype)
+ {
+ case TEXTOID:
+ result = text_lt((text *) datum1, (text *) datum2);
+ break;
+
+ case BPCHAROID:
+ result = bpcharlt((char *) datum1, (char *) datum2);
+ break;
+
+ case VARCHAROID:
+ result = varcharlt((char *) datum1, (char *) datum2);
+ break;
+
+ case NAMEOID:
+ result = namelt((NameData *) datum1, (NameData *) datum2);
+ break;
+
+ default:
+ elog(ERROR, "string_lessthan: unexpected datatype %u", datatype);
+ result = false;
+ break;
+ }
+
+ pfree(DatumGetPointer(datum1));
+ pfree(DatumGetPointer(datum2));
+
+ return result;
+}
+
+/* See if there is a binary op of the given name for the given datatype */
+static Oid
+find_operator(const char *opname, Oid datatype)
+{
+ HeapTuple optup;
+
+ optup = SearchSysCacheTuple(OPERNAME,
+ PointerGetDatum(opname),
+ ObjectIdGetDatum(datatype),
+ ObjectIdGetDatum(datatype),
+ CharGetDatum('b'));
+ if (!HeapTupleIsValid(optup))
+ return InvalidOid;
+ return optup->t_data->t_oid;
+}
+
+/*
+ * Generate a Datum of the appropriate type from a C string.
+ * Note that all of the supported types are pass-by-ref, so the
+ * returned value should be pfree'd if no longer needed.
+ */
+static Datum
+string_to_datum(const char *str, Oid datatype)
+{
+
+ /*
+ * We cheat a little by assuming that textin() will do for bpchar and
+ * varchar constants too...
+ */
+ if (datatype == NAMEOID)
+ return PointerGetDatum(namein((char *) str));
+ else
+ return PointerGetDatum(textin((char *) str));
+}
+
/*-------------------------------------------------------------------------
*
* Index cost estimation functions
projects / postgresql / commitdiff