Add prefix operator for TEXT type.

The prefix operator along with SP-GiST indexes can be used as an alternative
for LIKE 'word%' commands  and it doesn't have a limitation of string/prefix
length as B-Tree has.

Bump catalog version

Author: Ildus Kurbangaliev with some editorization by me
Review by: Arthur Zakirov, Alexander Korotkov, and me
Discussion: https://www.postgresql.org/message-id/flat/20180202180327.222b04b3@wp.localdomain

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 5abb1c46fbb86eff5f2b3c4f8f27df4147d02e83..9a1efc14cf76c2325a1be9150501cb1c5e347780 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -2274,6 +2274,21 @@
        <entry><literal>ph</literal></entry>
       </row>
 
+      <row>
+       <entry>
+        <indexterm>
+         <primary>starts_with</primary>
+        </indexterm>
+        <literal><function>starts_with(<parameter>string</parameter>, <parameter>prefix</parameter>)</function></literal>
+       </entry>
+       <entry><type>bool</type></entry>
+       <entry>
+        Returns true if <parameter>string</parameter> starts with <parameter>prefix</parameter>.
+       </entry>
+       <entry><literal>starts_with('alphabet', 'alph')</literal></entry>
+       <entry><literal>t</literal></entry>
+      </row>
+
       <row>
        <entry>
         <indexterm>
@@ -4033,6 +4048,12 @@ cast(-44 as bit(12))           <lineannotation>111111010100</lineannotation>
     ILIKE</function>, respectively.  All of these operators are
     <productname>PostgreSQL</productname>-specific.
    </para>
+
+   <para>
+    There is also the prefix operator <literal>^@</literal> and corresponding
+    <function>starts_with</function> function which covers cases when only
+    searching by beginning of the string is needed.
+   </para>
   </sect2>
 
 

diff --git a/doc/src/sgml/spgist.sgml b/doc/src/sgml/spgist.sgml
index e47f70be89bf3487bf39f5915fbe94fb64da4998..06b75190522f689467f19d1031713f373168c5fc 100644 (file)
--- a/doc/src/sgml/spgist.sgml
+++ b/doc/src/sgml/spgist.sgml
@@ -161,6 +161,7 @@
        <literal>~&lt;~</literal>
        <literal>~&gt;=~</literal>
        <literal>~&gt;~</literal>
+       <literal>^@</literal>
       </entry>
      </row>
      <row>

diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index f156b2166e680e77df41e98b6889959cd2bf0dfd..76c0305695b22ac3907da60714c20009016db85d 100644 (file)
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -67,6 +67,20 @@
  */
 #define SPGIST_MAX_PREFIX_LENGTH       Max((int) (BLCKSZ - 258 * 16 - 100), 32)
 
+/*
+ * Strategy for collation aware operator on text is equal to btree strategy
+ * plus value of 10.
+ *
+ * Current collation aware strategies and their corresponding btree strategies:
+ * 11 BTLessStrategyNumber
+ * 12 BTLessEqualStrategyNumber
+ * 14 BTGreaterEqualStrategyNumber
+ * 15 BTGreaterStrategyNumber
+ */
+#define SPG_STRATEGY_ADDITION  (10)
+#define SPG_IS_COLLATION_AWARE_STRATEGY(s) ((s) > SPG_STRATEGY_ADDITION \
+                                                                                && (s) != RTPrefixStrategyNumber)
+
 /* Struct for sorting values in picksplit */
 typedef struct spgNodePtr
 {
@@ -496,10 +510,10 @@ spg_text_inner_consistent(PG_FUNCTION_ARGS)
                         * well end with a partial multibyte character, so that applying
                         * any encoding-sensitive test to it would be risky anyhow.)
                         */
-                       if (strategy > 10)
+                       if (SPG_IS_COLLATION_AWARE_STRATEGY(strategy))
                        {
                                if (collate_is_c)
-                                       strategy -= 10;
+                                       strategy -= SPG_STRATEGY_ADDITION;
                                else
                                        continue;
                        }
@@ -526,6 +540,10 @@ spg_text_inner_consistent(PG_FUNCTION_ARGS)
                                        if (r < 0)
                                                res = false;
                                        break;
+                               case RTPrefixStrategyNumber:
+                                       if (r != 0)
+                                               res = false;
+                                       break;
                                default:
                                        elog(ERROR, "unrecognized strategy number: %d",
                                                 in->scankeys[j].sk_strategy);
@@ -605,10 +623,27 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
                int                     queryLen = VARSIZE_ANY_EXHDR(query);
                int                     r;
 
-               if (strategy > 10)
+               if (strategy == RTPrefixStrategyNumber)
+               {
+                       /*
+                        * if level >= length of query then reconstrValue is began with
+                        * query (prefix) string and we don't need to check it again.
+                        */
+
+                       res = (level >= queryLen) ||
+                                       DatumGetBool(DirectFunctionCall2(text_starts_with,
+                                                                out->leafValue, PointerGetDatum(query)));
+
+                       if (!res) /* no need to consider remaining conditions */
+                               break;
+
+                       continue;
+               }
+
+               if (SPG_IS_COLLATION_AWARE_STRATEGY(strategy))
                {
                        /* Collation-aware comparison */
-                       strategy -= 10;
+                       strategy -= SPG_STRATEGY_ADDITION;
 
                        /* If asserts enabled, verify encoding of reconstructed string */
                        Assert(pg_verifymbstr(fullValue, fullLen, false));

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index bf240aa9c5acdea2594588bf1297606cfb92c15f..f998d859c1c49775879bf8f7dd52506e07b7227c 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -1488,6 +1488,16 @@ likesel(PG_FUNCTION_ARGS)
 }
 
 /*
+ *             prefixsel                       - selectivity of prefix operator
+ */
+Datum
+prefixsel(PG_FUNCTION_ARGS)
+{
+       PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Prefix, false));
+}
+
+/*
+ *
  *             iclikesel                       - Selectivity of ILIKE pattern match.
  */
 Datum
@@ -2906,6 +2916,15 @@ likejoinsel(PG_FUNCTION_ARGS)
        PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like, false));
 }
 
+/*
+ *             prefixjoinsel                   - Join selectivity of prefix operator
+ */
+Datum
+prefixjoinsel(PG_FUNCTION_ARGS)
+{
+       PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Prefix, false));
+}
+
 /*
  *             iclikejoinsel                   - Join selectivity of ILIKE pattern match.
  */
@@ -5947,6 +5966,20 @@ pattern_fixed_prefix(Const *patt, Pattern_Type ptype, Oid collation,
                        result = regex_fixed_prefix(patt, true, collation,
                                                                                prefix, rest_selec);
                        break;
+               case Pattern_Type_Prefix:
+                       /* Prefix type work is trivial.  */
+                       result = Pattern_Prefix_Partial;
+                       *rest_selec = 1.0;      /* all */
+                       *prefix = makeConst(patt->consttype,
+                                                               patt->consttypmod,
+                                                               patt->constcollid,
+                                                               patt->constlen,
+                                                               datumCopy(patt->constvalue,
+                                                                                 patt->constbyval,
+                                                                                 patt->constlen),
+                                                               patt->constisnull,
+                                                               patt->constbyval);
+                       break;
                default:
                        elog(ERROR, "unrecognized ptype: %d", (int) ptype);
                        result = Pattern_Prefix_None;   /* keep compiler quiet */

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 4346410d5a9140d0667f2740c5dc2a920fea52ff..e8500b274dc70fd40cde0303c4294e8688a93229 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1761,6 +1761,34 @@ text_ge(PG_FUNCTION_ARGS)
        PG_RETURN_BOOL(result);
 }
 
+Datum
+text_starts_with(PG_FUNCTION_ARGS)
+{
+       Datum           arg1 = PG_GETARG_DATUM(0);
+       Datum           arg2 = PG_GETARG_DATUM(1);
+       bool            result;
+       Size            len1,
+                               len2;
+
+       len1 = toast_raw_datum_size(arg1);
+       len2 = toast_raw_datum_size(arg2);
+       if (len2 > len1)
+               result = false;
+       else
+       {
+               text       *targ1 = DatumGetTextPP(arg1);
+               text       *targ2 = DatumGetTextPP(arg2);
+
+               result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+                                                VARSIZE_ANY_EXHDR(targ2)) == 0);
+
+               PG_FREE_IF_COPY(targ1, 0);
+               PG_FREE_IF_COPY(targ2, 1);
+       }
+
+       PG_RETURN_BOOL(result);
+}
+
 Datum
 bttextcmp(PG_FUNCTION_ARGS)
 {

diff --git a/src/include/access/stratnum.h b/src/include/access/stratnum.h
index bddfac4c104d668a9a42694cefc53b275774f788..0db11a111794e12a1df8b422768398f8058cf963 100644 (file)
--- a/src/include/access/stratnum.h
+++ b/src/include/access/stratnum.h
@@ -68,8 +68,9 @@ typedef uint16 StrategyNumber;
 #define RTSubEqualStrategyNumber               25      /* for inet <<= */
 #define RTSuperStrategyNumber                  26      /* for inet << */
 #define RTSuperEqualStrategyNumber             27      /* for inet >>= */
+#define RTPrefixStrategyNumber                 28      /* for text ^@ */
 
-#define RTMaxStrategyNumber                            27
+#define RTMaxStrategyNumber                            28
 
 
 #endif                                                 /* STRATNUM_H */

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index b2806e6595a4e3eb98698e35bdd6b61bf1f4a644..5d55890b9dd35c0aca9e786903e8f2ab4bb5aac8 100644 (file)
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*                                                     yyyymmddN */
-#define CATALOG_VERSION_NO     201803311
+#define CATALOG_VERSION_NO     201804031
 
 #endif

diff --git a/src/include/catalog/pg_amop.h b/src/include/catalog/pg_amop.h
index 03af581df4e9d7ad46bb5cc85ab80b852c0b3036..00e77d4c61e5bd60e51d9a884e2c6050023e3a81 100644 (file)
--- a/src/include/catalog/pg_amop.h
+++ b/src/include/catalog/pg_amop.h
@@ -799,6 +799,7 @@ DATA(insert (       4017   25 25 11 s       664 4000 0 ));
 DATA(insert (  4017   25 25 12 s       665 4000 0 ));
 DATA(insert (  4017   25 25 14 s       667 4000 0 ));
 DATA(insert (  4017   25 25 15 s       666 4000 0 ));
+DATA(insert (  4017   25 25 28 s       3877 4000 0 ));
 
 /*
  * btree jsonb_ops

diff --git a/src/include/catalog/pg_operator.h b/src/include/catalog/pg_operator.h
index e74f963eb507f99fdd110318f93affe57c940bb4..6a6f708914ccf358a2e0a067569761f54c1938bf 100644 (file)
--- a/src/include/catalog/pg_operator.h
+++ b/src/include/catalog/pg_operator.h
@@ -134,6 +134,8 @@ DESCR("less than");
 DATA(insert OID =  98 ( "="               PGNSP PGUID b t t    25      25      16      98 531 texteq eqsel eqjoinsel ));
 DESCR("equal");
 #define TextEqualOperator      98
+DATA(insert OID =  3877 ( "^@"    PGNSP PGUID b f f    25      25      16      0 0 starts_with prefixsel prefixjoinsel ));
+DESCR("starts with");
 
 DATA(insert OID = 349 (  "||"     PGNSP PGUID b f f 2277 2283 2277 0 0 array_append   -           -     ));
 DESCR("append element onto end of array");

diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 90d994c71a4224fe01a4a0426494c384156e414e..9bf20c059bc5c129ae1d14d1c27662517bcb0659 100644 (file)
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -209,6 +209,7 @@ DATA(insert OID =  64 (  int2lt                        PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16
 DATA(insert OID =  65 (  int4eq                           PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "23 23" _null_ _null_ _null_ _null_ _null_ int4eq _null_ _null_ _null_ ));
 DATA(insert OID =  66 (  int4lt                           PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "23 23" _null_ _null_ _null_ _null_ _null_ int4lt _null_ _null_ _null_ ));
 DATA(insert OID =  67 (  texteq                           PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "25 25" _null_ _null_ _null_ _null_ _null_ texteq _null_ _null_ _null_ ));
+DATA(insert OID =  3696 ( starts_with     PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "25 25" _null_ _null_ _null_ _null_ _null_ text_starts_with _null_ _null_ _null_ ));
 DATA(insert OID =  68 (  xideq                    PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "28 28" _null_ _null_ _null_ _null_ _null_ xideq _null_ _null_ _null_ ));
 DATA(insert OID = 3308 (  xidneq                  PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "28 28" _null_ _null_ _null_ _null_ _null_ xidneq _null_ _null_ _null_ ));
 DATA(insert OID =  69 (  cideq                    PGNSP PGUID 12 1 0 0 0 f f t t f i s 2 0 16 "29 29" _null_ _null_ _null_ _null_ _null_ cideq _null_ _null_ _null_ ));
@@ -2584,6 +2585,10 @@ DATA(insert OID = 1828 ( nlikejoinsel            PGNSP PGUID 12 1 0 0 0 f f f t f s s 5 0
 DESCR("join selectivity of NOT LIKE");
 DATA(insert OID = 1829 ( icregexnejoinsel      PGNSP PGUID 12 1 0 0 0 f f f t f s s 5 0 701 "2281 26 2281 21 2281" _null_ _null_ _null_ _null_  _null_ icregexnejoinsel _null_ _null_ _null_ ));
 DESCR("join selectivity of case-insensitive regex non-match");
+DATA(insert OID = 3437 ( prefixsel                     PGNSP PGUID 12 1 0 0 0 f f f t f s s 4 0 701 "2281 26 2281 23" _null_ _null_ _null_ _null_ _null_ prefixsel _null_ _null_ _null_ ));
+DESCR("restriction selectivity of exact prefix");
+DATA(insert OID = 3438 ( prefixjoinsel         PGNSP PGUID 12 1 0 0 0 f f f t f s s 5 0 701 "2281 26 2281 21 2281" _null_ _null_ _null_ _null_  _null_ prefixjoinsel _null_ _null_ _null_ ));
+DESCR("join selectivity of exact prefix");
 
 /* Aggregate-related functions */
 DATA(insert OID = 1830 (  float8_avg      PGNSP PGUID 12 1 0 0 0 f f f t f i s 1 0 701 "1022" _null_ _null_ _null_ _null_ _null_ float8_avg _null_ _null_ _null_ ));

diff --git a/src/include/utils/selfuncs.h b/src/include/utils/selfuncs.h
index 299c9f846acda6cd154aa1155f884c4607be1268..95e44280c4c1bc0e678f723c7fbd166901d478ad 100644 (file)
--- a/src/include/utils/selfuncs.h
+++ b/src/include/utils/selfuncs.h
@@ -87,8 +87,11 @@ typedef struct VariableStatData
 
 typedef enum
 {
-       Pattern_Type_Like, Pattern_Type_Like_IC,
-       Pattern_Type_Regex, Pattern_Type_Regex_IC
+       Pattern_Type_Like,
+       Pattern_Type_Like_IC,
+       Pattern_Type_Regex,
+       Pattern_Type_Regex_IC,
+       Pattern_Type_Prefix
 } Pattern_Type;
 
 typedef enum

diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 057faff2e5c769845b91dfec26d15c85be1f2dab..09757c5a749217e31962dd06b98c2288aafc5955 100644 (file)
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -372,6 +372,12 @@ SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth
     48
 (1 row)
 
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+ count 
+-------
+     2
+(1 row)
+
 SELECT * FROM gpolygon_tbl ORDER BY f1 <-> '(0,0)'::point LIMIT 10;
                        f1                        
 -------------------------------------------------
@@ -1182,6 +1188,21 @@ SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth
     48
 (1 row)
 
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+                         QUERY PLAN                         
+------------------------------------------------------------
+ Aggregate
+   ->  Index Only Scan using sp_radix_ind on radix_text_tbl
+         Index Cond: (t ^@ 'Worth'::text)
+(3 rows)
+
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+ count 
+-------
+     2
+(1 row)
+
 EXPLAIN (COSTS OFF)
 SELECT * FROM gpolygon_tbl ORDER BY f1 <-> '(0,0)'::point LIMIT 10;
                      QUERY PLAN                      
@@ -1763,6 +1784,23 @@ SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth
     48
 (1 row)
 
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+                   QUERY PLAN                   
+------------------------------------------------
+ Aggregate
+   ->  Bitmap Heap Scan on radix_text_tbl
+         Recheck Cond: (t ^@ 'Worth'::text)
+         ->  Bitmap Index Scan on sp_radix_ind
+               Index Cond: (t ^@ 'Worth'::text)
+(5 rows)
+
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+ count 
+-------
+     2
+(1 row)
+
 RESET enable_seqscan;
 RESET enable_indexscan;
 RESET enable_bitmapscan;

diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out
index 01608d2c04460703a1248c27d8a48d9adc226bdd..a1e18a6cebaf9666a49e4faac1bb05ca6d4c88bd 100644 (file)
--- a/src/test/regress/expected/opr_sanity.out
+++ b/src/test/regress/expected/opr_sanity.out
@@ -718,6 +718,7 @@ sha224(bytea)
 sha256(bytea)
 sha384(bytea)
 sha512(bytea)
+starts_with(text,text)
 macaddr8_eq(macaddr8,macaddr8)
 macaddr8_lt(macaddr8,macaddr8)
 macaddr8_le(macaddr8,macaddr8)
@@ -1887,7 +1888,8 @@ ORDER BY 1, 2, 3;
        4000 |           25 | <<=
        4000 |           26 | >>
        4000 |           27 | >>=
-(121 rows)
+       4000 |           28 | ^@
+(122 rows)
 
 -- Check that all opclass search operators have selectivity estimators.
 -- This is not absolutely required, but it seems a reasonable thing

diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index 7f17588b0d7e19f11c08808bae1ca326cb447781..c9671a4e13e5669f0fab99e56732f41a106f7fd1 100644 (file)
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -224,6 +224,8 @@ SELECT count(*) FROM radix_text_tbl WHERE t >    'Worth
 
 SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth                         St  ';
 
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+
 SELECT * FROM gpolygon_tbl ORDER BY f1 <-> '(0,0)'::point LIMIT 10;
 
 SELECT circle_center(f1), round(radius(f1)) as radius FROM gcircle_tbl ORDER BY f1 <-> '(200,300)'::point LIMIT 10;
@@ -441,6 +443,10 @@ EXPLAIN (COSTS OFF)
 SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth                         St  ';
 SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth                         St  ';
 
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+
 EXPLAIN (COSTS OFF)
 SELECT * FROM gpolygon_tbl ORDER BY f1 <-> '(0,0)'::point LIMIT 10;
 SELECT * FROM gpolygon_tbl ORDER BY f1 <-> '(0,0)'::point LIMIT 10;
@@ -578,6 +584,10 @@ EXPLAIN (COSTS OFF)
 SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth                         St  ';
 SELECT count(*) FROM radix_text_tbl WHERE t ~>~  'Worth                         St  ';
 
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+SELECT count(*) FROM radix_text_tbl WHERE t ^@  'Worth';
+
 RESET enable_seqscan;
 RESET enable_indexscan;
 RESET enable_bitmapscan;