From 906282444a5f9eba1067d3515de7ab594ef0d900 Mon Sep 17 00:00:00 2001 From: Yugo Nagata Date: Thu, 19 Dec 2024 23:41:07 +0900 Subject: [PATCH v2 2/3] Allow ILIKE forward matching to use btree index Previously, ILIKE could not use btree index if the pattern has case-varying characters. To enable it, the planner support function converts an ILINK operator expression to OR clause that contains two index clauses for the upper letter and the lower letter respectively. For example, "t ILIKE '123foo%'" can be converted to "(t <= '123F'AND t > '123G') OR (t <= '123f' AND t < '123g')", and bitmap index scan plan could be used for this. --- src/backend/utils/adt/like_support.c | 141 ++++++++++++++---- src/test/regress/expected/btree_index.out | 15 +- .../regress/expected/collate.icu.utf8.out | 22 ++- src/test/regress/sql/collate.icu.utf8.sql | 4 +- 4 files changed, 137 insertions(+), 45 deletions(-) diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c index 8fdc677371..2344615038 100644 --- a/src/backend/utils/adt/like_support.c +++ b/src/backend/utils/adt/like_support.c @@ -66,7 +66,10 @@ typedef enum typedef enum { - Pattern_Prefix_None, Pattern_Prefix_Partial, Pattern_Prefix_Exact, + Pattern_Prefix_None, + Pattern_Prefix_Partial, + Pattern_Prefix_Partial_IC, + Pattern_Prefix_Exact, } Pattern_Prefix_Status; static Node *like_regex_support(Node *rawreq, Pattern_Type ptype); @@ -245,7 +248,7 @@ match_pattern_prefix(Node *leftop, Oid opfamily, Oid indexcollation) { - List *result; + List *result = NIL; Const *patt; Const *prefix; Pattern_Prefix_Status pstatus; @@ -259,6 +262,8 @@ match_pattern_prefix(Node *leftop, Expr *expr; FmgrInfo ltproc; Const *greaterstr; + List *prefixes; + ListCell *lc; /* * Can't do anything with a non-constant or NULL pattern argument. @@ -434,35 +439,112 @@ match_pattern_prefix(Node *leftop, return NIL; /* - * We can always say "x >= prefix". + * If the pattern for case-insensiive matching has a case-varying + * character, make two prefixes including the upper letter and the + * lower letter respectively. For example, if the pattern is + * '123foo%', we get '123F' and '123f' as prefixes. */ - if (!op_in_opfamily(geopr, opfamily)) - return NIL; - expr = make_opclause(geopr, BOOLOID, false, - (Expr *) leftop, (Expr *) prefix, - InvalidOid, indexcollation); - result = list_make1(expr); - - /*------- - * If we can create a string larger than the prefix, we can say - * "x < greaterstr". NB: we rely on make_greater_string() to generate - * a guaranteed-greater string, not just a probably-greater string. - * In general this is only guaranteed in C locale, so we'd better be - * using a C-locale index collation. - *------- - */ - if (!op_in_opfamily(ltopr, opfamily)) - return result; - fmgr_info(get_opcode(ltopr), <proc); - greaterstr = make_greater_string(prefix, <proc, indexcollation); - if (greaterstr) + if (pstatus == Pattern_Prefix_Partial_IC) + { + int prefix_len; + Datum first_letter; + Datum upper_letter; + Datum lower_letter; + const char *prefix_l; + const char *prefix_u; + + Assert(ptype == Pattern_Type_Like_IC); + + /* get the first case-varying characketer in the pattern */ + prefix_len = DatumGetInt32(DirectFunctionCall1Coll(textlen, + indexcollation, + prefix->constvalue)); + first_letter = DirectFunctionCall3Coll(text_substr, indexcollation, + patt->constvalue, + Int32GetDatum(prefix_len + 1), + Int32GetDatum(1)); + + + /* prefix followed by the upper letter */ + upper_letter = DirectFunctionCall1Coll(upper, indexcollation, + first_letter); + prefix_u = TextDatumGetCString(DirectFunctionCall2Coll(textcat, + indexcollation, + prefix->constvalue, + upper_letter)); + prefixes = list_make1(string_to_const(prefix_u, prefix->consttype)); + + /* prefix followed by the lower letter */ + lower_letter = DirectFunctionCall1Coll(lower, indexcollation, + first_letter); + prefix_l = TextDatumGetCString(DirectFunctionCall2Coll(textcat, + indexcollation, + prefix->constvalue, + lower_letter)); + if (!DatumGetBool(DirectFunctionCall2Coll(texteq, + indexcollation, + CStringGetTextDatum(prefix_u), + CStringGetTextDatum(prefix_l)))) + prefixes = lappend(prefixes, string_to_const(prefix_l, prefix->consttype)); + } + else + prefixes = list_make1(prefix); + + foreach (lc, prefixes) { - expr = make_opclause(ltopr, BOOLOID, false, - (Expr *) leftop, (Expr *) greaterstr, + List *clauses; + + prefix = (Const *) lfirst(lc); + + /* + * We can always say "x >= prefix". + */ + if (!op_in_opfamily(geopr, opfamily)) + return NIL; + expr = make_opclause(geopr, BOOLOID, false, + (Expr *) leftop, (Expr *) prefix, InvalidOid, indexcollation); - result = lappend(result, expr); + clauses = list_make1(expr); + + /*------- + * If we can create a string larger than the prefix, we can say + * "x < greaterstr". NB: we rely on make_greater_string() to generate + * a guaranteed-greater string, not just a probably-greater string. + * In general this is only guaranteed in C locale, so we'd better be + * using a C-locale index collation. + *------- + */ + if (op_in_opfamily(ltopr, opfamily)) + { + fmgr_info(get_opcode(ltopr), <proc); + greaterstr = make_greater_string(prefix, <proc, indexcollation); + if (greaterstr) + { + expr = make_opclause(ltopr, BOOLOID, false, + (Expr *) leftop, (Expr *) greaterstr, + InvalidOid, indexcollation); + clauses = lappend(clauses, expr); + } + } + + /* + * If case-insensitive pattern matching generated two clauses for + * uppder and lower letters, convert them to explicit AND because + * they will be under OR later. + */ + if (pstatus == Pattern_Prefix_Partial_IC && list_length(prefixes) > 1) + result = lappend(result, make_ands_explicit(clauses)); + else + result = clauses; } + /* + * If case-insensitive pattern matching generated two clauses for upper and + * lower letters, OR them. + */ + if (pstatus == Pattern_Prefix_Partial_IC && list_length(prefixes) > 1) + result = list_make1(make_orclause(result)); + return result; } @@ -997,6 +1079,7 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation, match_pos; bool is_multibyte = (pg_database_encoding_max_length() > 1); pg_locale_t locale = 0; + bool has_case_varying = false; /* the right-hand const is type text or bytea */ Assert(typeid == BYTEAOID || typeid == TEXTOID); @@ -1058,7 +1141,10 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation, /* Stop if case-varying character (it's sort of a wildcard) */ if (case_insensitive && pattern_char_isalpha(patt[pos], is_multibyte, locale)) + { + has_case_varying = true; break; + } match[match_pos++] = patt[pos]; } @@ -1077,6 +1163,9 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation, pfree(patt); pfree(match); + if (case_insensitive && has_case_varying) + return Pattern_Prefix_Partial_IC; + /* in LIKE, an empty pattern is an exact match! */ if (pos == pattlen) return Pattern_Prefix_Exact; /* reached end of pattern, so exact */ diff --git a/src/test/regress/expected/btree_index.out b/src/test/regress/expected/btree_index.out index 8879554c3f..6ffad39dad 100644 --- a/src/test/regress/expected/btree_index.out +++ b/src/test/regress/expected/btree_index.out @@ -459,14 +459,19 @@ select proname from pg_proc where proname ilike '00%foo' order by 1; explain (costs off) select proname from pg_proc where proname ilike 'ri%foo' order by 1; - QUERY PLAN ----------------------------------------------- + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Sort Sort Key: proname - -> Seq Scan on pg_proc - Disabled: true + -> Bitmap Heap Scan on pg_proc + Recheck Cond: (((proname >= 'R'::text) AND (proname < 'S'::text) AND (proname ~~* 'ri%foo'::text)) OR ((proname >= 'r'::text) AND (proname < 's'::text) AND (proname ~~* 'ri%foo'::text))) Filter: (proname ~~* 'ri%foo'::text) -(5 rows) + -> BitmapOr + -> Bitmap Index Scan on pg_proc_proname_args_nsp_index + Index Cond: ((proname >= 'R'::text) AND (proname < 'S'::text)) + -> Bitmap Index Scan on pg_proc_proname_args_nsp_index + Index Cond: ((proname >= 'r'::text) AND (proname < 's'::text)) +(10 rows) reset enable_seqscan; reset enable_indexscan; diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out index d4f327636f..f13f9e1245 100644 --- a/src/test/regress/expected/collate.icu.utf8.out +++ b/src/test/regress/expected/collate.icu.utf8.out @@ -988,14 +988,13 @@ SELECT relname, pg_get_indexdef(oid) FROM pg_class WHERE relname LIKE 'collate_t set enable_seqscan = off; explain (costs off) select * from collate_test1 where b ilike 'abc'; - QUERY PLAN -------------------------------- - Seq Scan on collate_test1 - Disabled: true + QUERY PLAN +------------------------------------------------------ + Index Scan using collate_test1_idx3 on collate_test1 Filter: (b ~~* 'abc'::text) -(3 rows) +(2 rows) -select * from collate_test1 where b ilike 'abc'; +select * from collate_test1 where b ilike 'abc' order by 1; a | b ---+----- 1 | abc @@ -1004,14 +1003,13 @@ select * from collate_test1 where b ilike 'abc'; explain (costs off) select * from collate_test1 where b ilike 'ABC'; - QUERY PLAN -------------------------------- - Seq Scan on collate_test1 - Disabled: true + QUERY PLAN +------------------------------------------------------ + Index Scan using collate_test1_idx3 on collate_test1 Filter: (b ~~* 'ABC'::text) -(3 rows) +(2 rows) -select * from collate_test1 where b ilike 'ABC'; +select * from collate_test1 where b ilike 'ABC' order by 1; a | b ---+----- 1 | abc diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql index 5ee2da4e0e..948201c3e1 100644 --- a/src/test/regress/sql/collate.icu.utf8.sql +++ b/src/test/regress/sql/collate.icu.utf8.sql @@ -344,10 +344,10 @@ SELECT relname, pg_get_indexdef(oid) FROM pg_class WHERE relname LIKE 'collate_t set enable_seqscan = off; explain (costs off) select * from collate_test1 where b ilike 'abc'; -select * from collate_test1 where b ilike 'abc'; +select * from collate_test1 where b ilike 'abc' order by 1; explain (costs off) select * from collate_test1 where b ilike 'ABC'; -select * from collate_test1 where b ilike 'ABC'; +select * from collate_test1 where b ilike 'ABC' order by 1; reset enable_seqscan; -- 2.34.1