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Adjust string comparison in jsonpath
We have implemented jsonpath string comparison using default database locale. However, standard requires us to compare Unicode codepoints. This commit implements that, but for performance reasons we still use per-byte comparison for "==" operator. Thus, for consistency other comparison operators do per-byte comparison if Unicode codepoints appear to be equal. In some edge cases, when same Unicode codepoints have different binary representations in database encoding, we diverge standard to achieve better performance of "==" operator. In future to implement strict standard conformance, we can do normalization of input JSON strings. Original patch was written by Nikita Glukhov, rewritten by me. Reported-by: Markus Winand Discussion: https://postgr.es/m/8B7FA3B4-328D-43D7-95A8-37B8891B8C78%40winand.at Author: Nikita Glukhov, Alexander Korotkov Backpatch-through: 12
This commit is contained in:
Alexander Korotkov
parent
cabe0f298e
commit
d54ceb9e17
@ -1980,6 +1980,73 @@ executeComparison(JsonPathItem *cmp, JsonbValue *lv, JsonbValue *rv, void *p)
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return compareItems(cmp->type, lv, rv);
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}
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/*
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* Perform per-byte comparison of two strings.
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*/
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static int
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binaryCompareStrings(const char *s1, int len1,
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const char *s2, int len2)
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{
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int cmp;
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cmp = memcmp(s1, s2, Min(len1, len2));
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if (cmp != 0)
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return cmp;
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if (len1 == len2)
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return 0;
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return len1 < len2 ? -1 : 1;
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}
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/*
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* Compare two strings in the current server encoding using Unicode codepoint
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* collation.
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*/
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static int
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compareStrings(const char *mbstr1, int mblen1,
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const char *mbstr2, int mblen2)
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{
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if (GetDatabaseEncoding() == PG_SQL_ASCII ||
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GetDatabaseEncoding() == PG_UTF8)
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{
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/*
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* It's known property of UTF-8 strings that their per-byte comparison
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* result matches codepoints comparison result. ASCII can be
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* considered as special case of UTF-8.
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*/
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return binaryCompareStrings(mbstr1, mblen1, mbstr2, mblen2);
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}
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else
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{
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/* We have to convert other encodings to UTF-8 first, then compare. */
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char *utf8str1 = pg_server_to_any(mbstr1, mblen1, PG_UTF8),
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*utf8str2 = pg_server_to_any(mbstr2, mblen2, PG_UTF8);
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int cmp;
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cmp = binaryCompareStrings(utf8str1, strlen(utf8str1),
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utf8str2, strlen(utf8str2));
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pfree(utf8str1);
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pfree(utf8str2);
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/*
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* When all Unicode codepoints are equal, return result of binary
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* comparison. In some edge cases, same characters may have different
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* representations in encoding. Then our behavior could diverge from
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* standard. However, that allow us to do simple binary comparison
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* for "==" operator, which is performance critical in typical cases.
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* In future to implement strict standard conformance, we can do
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* normalization of input JSON strings.
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*/
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if (cmp == 0)
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return binaryCompareStrings(mbstr1, mblen1, mbstr2, mblen2);
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else
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return cmp;
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}
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}
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/*
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* Compare two SQL/JSON items using comparison operation 'op'.
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*/
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@ -2022,9 +2089,8 @@ compareItems(int32 op, JsonbValue *jb1, JsonbValue *jb2)
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jb2->val.string.val,
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jb1->val.string.len) ? jpbFalse : jpbTrue;
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cmp = varstr_cmp(jb1->val.string.val, jb1->val.string.len,
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jb2->val.string.val, jb2->val.string.len,
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DEFAULT_COLLATION_OID);
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cmp = compareStrings(jb1->val.string.val, jb1->val.string.len,
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jb2->val.string.val, jb2->val.string.len);
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break;
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case jbvBinary:
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@ -1833,3 +1833,166 @@ SELECT jsonb_path_match('[{"a": 1}, {"a": 2}]', '$[*].a > 1');
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t
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(1 row)
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-- test string comparison (Unicode codepoint collation)
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WITH str(j, num) AS
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(
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SELECT jsonb_build_object('s', s), num
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FROM unnest('{"", "a", "ab", "abc", "abcd", "b", "A", "AB", "ABC", "ABc", "ABcD", "B"}'::text[]) WITH ORDINALITY AS a(s, num)
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)
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SELECT
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s1.j, s2.j,
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jsonb_path_query_first(s1.j, '$.s < $s', vars => s2.j) lt,
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jsonb_path_query_first(s1.j, '$.s <= $s', vars => s2.j) le,
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jsonb_path_query_first(s1.j, '$.s == $s', vars => s2.j) eq,
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jsonb_path_query_first(s1.j, '$.s >= $s', vars => s2.j) ge,
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jsonb_path_query_first(s1.j, '$.s > $s', vars => s2.j) gt
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FROM str s1, str s2
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ORDER BY s1.num, s2.num;
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j | j | lt | le | eq | ge | gt
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---------------+---------------+-------+-------+-------+-------+-------
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{"s": ""} | {"s": ""} | false | true | true | true | false
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{"s": ""} | {"s": "a"} | true | true | false | false | false
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{"s": ""} | {"s": "ab"} | true | true | false | false | false
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{"s": ""} | {"s": "abc"} | true | true | false | false | false
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{"s": ""} | {"s": "abcd"} | true | true | false | false | false
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{"s": ""} | {"s": "b"} | true | true | false | false | false
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{"s": ""} | {"s": "A"} | true | true | false | false | false
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{"s": ""} | {"s": "AB"} | true | true | false | false | false
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{"s": ""} | {"s": "ABC"} | true | true | false | false | false
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{"s": ""} | {"s": "ABc"} | true | true | false | false | false
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{"s": ""} | {"s": "ABcD"} | true | true | false | false | false
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{"s": ""} | {"s": "B"} | true | true | false | false | false
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{"s": "a"} | {"s": ""} | false | false | false | true | true
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{"s": "a"} | {"s": "a"} | false | true | true | true | false
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{"s": "a"} | {"s": "ab"} | true | true | false | false | false
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{"s": "a"} | {"s": "abc"} | true | true | false | false | false
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{"s": "a"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "a"} | {"s": "b"} | true | true | false | false | false
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{"s": "a"} | {"s": "A"} | false | false | false | true | true
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{"s": "a"} | {"s": "AB"} | false | false | false | true | true
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{"s": "a"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "a"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "a"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "a"} | {"s": "B"} | false | false | false | true | true
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{"s": "ab"} | {"s": ""} | false | false | false | true | true
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{"s": "ab"} | {"s": "a"} | false | false | false | true | true
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{"s": "ab"} | {"s": "ab"} | false | true | true | true | false
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{"s": "ab"} | {"s": "abc"} | true | true | false | false | false
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{"s": "ab"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "ab"} | {"s": "b"} | true | true | false | false | false
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{"s": "ab"} | {"s": "A"} | false | false | false | true | true
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{"s": "ab"} | {"s": "AB"} | false | false | false | true | true
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{"s": "ab"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "ab"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "ab"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "ab"} | {"s": "B"} | false | false | false | true | true
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{"s": "abc"} | {"s": ""} | false | false | false | true | true
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{"s": "abc"} | {"s": "a"} | false | false | false | true | true
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{"s": "abc"} | {"s": "ab"} | false | false | false | true | true
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{"s": "abc"} | {"s": "abc"} | false | true | true | true | false
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{"s": "abc"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "abc"} | {"s": "b"} | true | true | false | false | false
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{"s": "abc"} | {"s": "A"} | false | false | false | true | true
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{"s": "abc"} | {"s": "AB"} | false | false | false | true | true
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{"s": "abc"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "abc"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "abc"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "abc"} | {"s": "B"} | false | false | false | true | true
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{"s": "abcd"} | {"s": ""} | false | false | false | true | true
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{"s": "abcd"} | {"s": "a"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "ab"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "abc"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "abcd"} | false | true | true | true | false
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{"s": "abcd"} | {"s": "b"} | true | true | false | false | false
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{"s": "abcd"} | {"s": "A"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "AB"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "abcd"} | {"s": "B"} | false | false | false | true | true
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{"s": "b"} | {"s": ""} | false | false | false | true | true
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{"s": "b"} | {"s": "a"} | false | false | false | true | true
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{"s": "b"} | {"s": "ab"} | false | false | false | true | true
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{"s": "b"} | {"s": "abc"} | false | false | false | true | true
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{"s": "b"} | {"s": "abcd"} | false | false | false | true | true
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{"s": "b"} | {"s": "b"} | false | true | true | true | false
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{"s": "b"} | {"s": "A"} | false | false | false | true | true
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{"s": "b"} | {"s": "AB"} | false | false | false | true | true
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{"s": "b"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "b"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "b"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "b"} | {"s": "B"} | false | false | false | true | true
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{"s": "A"} | {"s": ""} | false | false | false | true | true
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{"s": "A"} | {"s": "a"} | true | true | false | false | false
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{"s": "A"} | {"s": "ab"} | true | true | false | false | false
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{"s": "A"} | {"s": "abc"} | true | true | false | false | false
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{"s": "A"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "A"} | {"s": "b"} | true | true | false | false | false
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{"s": "A"} | {"s": "A"} | false | true | true | true | false
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{"s": "A"} | {"s": "AB"} | true | true | false | false | false
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{"s": "A"} | {"s": "ABC"} | true | true | false | false | false
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{"s": "A"} | {"s": "ABc"} | true | true | false | false | false
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{"s": "A"} | {"s": "ABcD"} | true | true | false | false | false
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{"s": "A"} | {"s": "B"} | true | true | false | false | false
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{"s": "AB"} | {"s": ""} | false | false | false | true | true
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{"s": "AB"} | {"s": "a"} | true | true | false | false | false
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{"s": "AB"} | {"s": "ab"} | true | true | false | false | false
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{"s": "AB"} | {"s": "abc"} | true | true | false | false | false
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{"s": "AB"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "AB"} | {"s": "b"} | true | true | false | false | false
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{"s": "AB"} | {"s": "A"} | false | false | false | true | true
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{"s": "AB"} | {"s": "AB"} | false | true | true | true | false
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{"s": "AB"} | {"s": "ABC"} | true | true | false | false | false
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{"s": "AB"} | {"s": "ABc"} | true | true | false | false | false
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{"s": "AB"} | {"s": "ABcD"} | true | true | false | false | false
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{"s": "AB"} | {"s": "B"} | true | true | false | false | false
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{"s": "ABC"} | {"s": ""} | false | false | false | true | true
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{"s": "ABC"} | {"s": "a"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "ab"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "abc"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "b"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "A"} | false | false | false | true | true
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{"s": "ABC"} | {"s": "AB"} | false | false | false | true | true
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{"s": "ABC"} | {"s": "ABC"} | false | true | true | true | false
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{"s": "ABC"} | {"s": "ABc"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "ABcD"} | true | true | false | false | false
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{"s": "ABC"} | {"s": "B"} | true | true | false | false | false
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{"s": "ABc"} | {"s": ""} | false | false | false | true | true
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{"s": "ABc"} | {"s": "a"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "ab"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "abc"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "b"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "A"} | false | false | false | true | true
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{"s": "ABc"} | {"s": "AB"} | false | false | false | true | true
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{"s": "ABc"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "ABc"} | {"s": "ABc"} | false | true | true | true | false
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{"s": "ABc"} | {"s": "ABcD"} | true | true | false | false | false
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{"s": "ABc"} | {"s": "B"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": ""} | false | false | false | true | true
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{"s": "ABcD"} | {"s": "a"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": "ab"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": "abc"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": "b"} | true | true | false | false | false
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{"s": "ABcD"} | {"s": "A"} | false | false | false | true | true
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{"s": "ABcD"} | {"s": "AB"} | false | false | false | true | true
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{"s": "ABcD"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "ABcD"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "ABcD"} | {"s": "ABcD"} | false | true | true | true | false
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{"s": "ABcD"} | {"s": "B"} | true | true | false | false | false
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{"s": "B"} | {"s": ""} | false | false | false | true | true
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{"s": "B"} | {"s": "a"} | true | true | false | false | false
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{"s": "B"} | {"s": "ab"} | true | true | false | false | false
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{"s": "B"} | {"s": "abc"} | true | true | false | false | false
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{"s": "B"} | {"s": "abcd"} | true | true | false | false | false
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{"s": "B"} | {"s": "b"} | true | true | false | false | false
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{"s": "B"} | {"s": "A"} | false | false | false | true | true
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{"s": "B"} | {"s": "AB"} | false | false | false | true | true
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{"s": "B"} | {"s": "ABC"} | false | false | false | true | true
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{"s": "B"} | {"s": "ABc"} | false | false | false | true | true
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{"s": "B"} | {"s": "ABcD"} | false | false | false | true | true
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{"s": "B"} | {"s": "B"} | false | true | true | true | false
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(144 rows)
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@ -387,3 +387,19 @@ SELECT jsonb_path_match('[true, true]', '$[*]', silent => false);
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SELECT jsonb '[{"a": 1}, {"a": 2}]' @@ '$[*].a > 1';
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SELECT jsonb '[{"a": 1}, {"a": 2}]' @@ '$[*].a > 2';
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SELECT jsonb_path_match('[{"a": 1}, {"a": 2}]', '$[*].a > 1');
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-- test string comparison (Unicode codepoint collation)
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WITH str(j, num) AS
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(
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SELECT jsonb_build_object('s', s), num
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FROM unnest('{"", "a", "ab", "abc", "abcd", "b", "A", "AB", "ABC", "ABc", "ABcD", "B"}'::text[]) WITH ORDINALITY AS a(s, num)
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)
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SELECT
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s1.j, s2.j,
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jsonb_path_query_first(s1.j, '$.s < $s', vars => s2.j) lt,
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jsonb_path_query_first(s1.j, '$.s <= $s', vars => s2.j) le,
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jsonb_path_query_first(s1.j, '$.s == $s', vars => s2.j) eq,
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jsonb_path_query_first(s1.j, '$.s >= $s', vars => s2.j) ge,
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jsonb_path_query_first(s1.j, '$.s > $s', vars => s2.j) gt
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FROM str s1, str s2
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ORDER BY s1.num, s2.num;
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