[tarantool-patches] [PATCH] sql: Duplicate key error for a non-unique index

[Stanislav Zudin <szudin@tarantool.org>]

Adds collation analysis into creating of a composite key for
index tuples.
The keys of secondary index consist of parts defined for index itself
combined with parts defined for primary key.
The duplicate parts are ignored. But the search of duplicates didn't
take the collation into consideration.
If non-unique secondary index contained primary key columns their
parts from the primary key were omitted. This fact caused an issue.

Closes #3537
---
Branch: https://github.com/tarantool/tarantool/tree/stanztt/gh-3537-nonunique-index-dup-key-error
Issue: https://github.com/tarantool/tarantool/issues/3537

 src/box/key_def.c           | 44 +++++++++++++++++++++++++++++++++++--
 src/coll.c                  |  1 +
 src/coll.h                  |  2 ++
 test/sql/collation.result   | 14 ++++++++++++
 test/sql/collation.test.lua |  8 +++++++
 5 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/src/box/key_def.c b/src/box/key_def.c
index 9411ade39..b5b4c6edf 100644
--- a/src/box/key_def.c
+++ b/src/box/key_def.c
@@ -37,6 +37,7 @@
 #include "schema_def.h"
 #include "coll_id_cache.h"
 #include "small/region.h"
+#include "coll.h"
 
 const char *sort_order_strs[] = { "asc", "desc", "undef" };
 
@@ -596,6 +597,45 @@ key_def_find_by_fieldno(const struct key_def *key_def, uint32_t fieldno)
 	return key_def_find(key_def, &part);
 }
 
+static bool
+key_part_coll_equal(const struct coll* sec_coll, const struct coll* pk_coll)
+{
+	if (sec_coll == pk_coll)
+		return true;
+	/* If they're not the same object
+	 * compare their strength */
+	enum coll_icu_strength sec_strength = sec_coll
+		? sec_coll->strength
+		: COLL_ICU_STRENGTH_DEFAULT;
+	enum coll_icu_strength pk_strength = pk_coll
+		? pk_coll->strength
+		: COLL_ICU_STRENGTH_DEFAULT;
+	/* If collation of the secondary key beats
+	 * the PK key's collation then they're not
+	 * equal and the secondary key must be
+	 * combined with the primary one. */
+	if (sec_strength > pk_strength)
+		return false;
+	else
+		return true;
+}
+
+static const struct key_part *
+key_def_find_with_coll(const struct key_def *sec_key_def, const struct key_part *pk_key_part)
+{
+	const struct key_part *part = sec_key_def->parts;
+	const struct key_part *end = part + sec_key_def->part_count;
+	for (; part != end; part++) {
+		if (part->fieldno == pk_key_part->fieldno &&
+		    key_part_coll_equal(part->coll, pk_key_part->coll) &&
+		    json_path_cmp(part->path, part->path_len,
+				  pk_key_part->path, pk_key_part->path_len,
+				  TUPLE_INDEX_BASE) == 0)
+			return part;
+	}
+	return NULL;
+}
+
 const struct key_part *
 key_def_find(const struct key_def *key_def, const struct key_part *to_find)
 {
@@ -639,7 +679,7 @@ key_def_merge(const struct key_def *first, const struct key_def *second)
 	part = second->parts;
 	end = part + second->part_count;
 	for (; part != end; part++) {
-		if (key_def_find(first, part) != NULL)
+		if (key_def_find_with_coll(first, part) != NULL)
 			--new_part_count;
 		else
 			sz += part->path_len;
@@ -677,7 +717,7 @@ key_def_merge(const struct key_def *first, const struct key_def *second)
 	part = second->parts;
 	end = part + second->part_count;
 	for (; part != end; part++) {
-		if (key_def_find(first, part) != NULL)
+		if (key_def_find_with_coll(first, part) != NULL)
 			continue;
 		key_def_set_part(new_def, pos++, part->fieldno, part->type,
 				 part->nullable_action, part->coll,
diff --git a/src/coll.c b/src/coll.c
index 6d9c44dbf..8f9dcbac2 100644
--- a/src/coll.c
+++ b/src/coll.c
@@ -320,6 +320,7 @@ coll_new(const struct coll_def *def)
 	}
 	memcpy((char *) coll->fingerprint, fingerprint, fingerprint_len + 1);
 	coll->refs = 1;
+	coll->strength = def->icu.strength;
 	coll->type = def->type;
 	switch (coll->type) {
 	case COLL_TYPE_ICU:
diff --git a/src/coll.h b/src/coll.h
index 9c725712a..2412f8032 100644
--- a/src/coll.h
+++ b/src/coll.h
@@ -56,6 +56,8 @@ struct UCollator;
 struct coll {
 	/** Collation type. */
 	enum coll_type type;
+	/** Strength ICU settings */
+	enum coll_icu_strength strength;
 	/** ICU collation specific data. */
 	struct UCollator *collator;
 	/** String comparator. */
diff --git a/test/sql/collation.result b/test/sql/collation.result
index 5721ef854..94e03d624 100644
--- a/test/sql/collation.result
+++ b/test/sql/collation.result
@@ -325,3 +325,17 @@ box.sql.execute("DROP TABLE t1;")
 box.sql.execute("DROP TABLE t0;")
 ---
 ...
+-- gh-3537 Duplicate key error for an index that is not unique
+--
+box.sql.execute('CREATE TABLE t3 (s1 CHAR(5) PRIMARY KEY);')
+---
+...
+box.sql.execute('CREATE INDEX i3 ON t3 (s1 collate "unicode_ci");')
+---
+...
+box.sql.execute("INSERT INTO t3 VALUES ('a');")
+---
+...
+box.sql.execute("INSERT INTO t3 VALUES ('A');")
+---
+...
diff --git a/test/sql/collation.test.lua b/test/sql/collation.test.lua
index 4c649a444..7210c8e9e 100644
--- a/test/sql/collation.test.lua
+++ b/test/sql/collation.test.lua
@@ -126,3 +126,11 @@ box.sql.execute("SELECT * FROM t1;")
 box.sql.execute("SELECT s1 FROM t0;")
 box.sql.execute("DROP TABLE t1;")
 box.sql.execute("DROP TABLE t0;")
+
+-- gh-3537 Duplicate key error for an index that is not unique
+--
+box.sql.execute('CREATE TABLE t3 (s1 CHAR(5) PRIMARY KEY);')
+box.sql.execute('CREATE INDEX i3 ON t3 (s1 collate "unicode_ci");')
+box.sql.execute("INSERT INTO t3 VALUES ('a');")
+box.sql.execute("INSERT INTO t3 VALUES ('A');")
+
-- 
2.17.1