Re: [Tarantool-patches] [PATCH v2 2/3] sql: make constraint operations transactional

[Roman Khabibov <roman.habibov@tarantool.org>]

> On Nov 30, 2019, at 04:03, Vladislav Shpilevoy <v.shpilevoy@tarantool.org> wrote:
> 
> Thanks for the patch!
> 
> The commit below (or at least the commit message) was outdated.
> I see a different version on the branch. Below I copypaste the
> branch's version, and review it.
> 
> See 14 comments below.
> 
>>    Put constraint names into the space's hash table and drop them on
>>    replace in correspondig system spaces (_index, _fk_constraint,
> 
> 1. correspondig -> corresponding
Done.

>>    _ck_constraint).
>> 
>>    Closes #3503
>> 
>>    @TarantoolBot document
>>    Title: Constraints
>>    Now, names of constraints must be unique within one space.
> 
> 2. Now, imagine that you are a technical writer. You don't
> run and test Tarantool every day. And you don't know what,
> how, when, and where do we support. What are the problems,
> features, plans. Your task is simple - you take a ticket
> from tarantool/doc, and transform it into something that is
> ok to be placed on the site. Into a good English text, with
> rich details, with omission of not needed information. You
> may fix some of the old documentation affected by that ticket.
> You may add pictures, diagrams.
> 
> And then imagine you got such a ticket as you provided here.
> Sorry, but this is just nothing. That is like if I would ask
> you to 'fix an assertion in box'. What assertion? Where in
> the box? What is a reproducer?
> 
> You need to explain, what do you mean as constraints; what
> if uniqueness is violated; does letter case matter; what are
> examples; does language matter (Lua, SQL, binary) etc.
Done.

>> 
>> diff --git a/src/box/alter.cc b/src/box/alter.cc
>> index 4a3241a79..4bb8b8556 100644
>> --- a/src/box/alter.cc
>> +++ b/src/box/alter.cc
>> @@ -1765,6 +1766,38 @@ MoveCkConstraints::rollback(struct alter_space *alter)
>> 	space_swap_ck_constraint(alter->new_space, alter->old_space);
>> }
>> 
>> +/**
>> + * Move constraint names hash table from old space to a new one.
>> + */
>> +class MoveConstraints: public AlterSpaceOp
>> +{
>> +	inline void space_swap_constraint(struct space *old_space,
>> +				   struct space *new_space);
>> +public:
>> +	MoveConstraints(struct alter_space *alter) : AlterSpaceOp(alter) {}
>> +	virtual void alter(struct alter_space *alter);
>> +	virtual void rollback(struct alter_space *alter);
>> +};
>> +
>> +inline void
>> +MoveConstraints::space_swap_constraint(struct space *old_space,
>> +				       struct space *new_space)
>> +{
>> +	SWAP(new_space->constraint_names, old_space->constraint_names);
> 
> 3. So this is not inlined as a I asked. Perhaps that was
> misunderstanding. I meant literally inline it. Not add
> 'inline' keyword. That is a one-liner function, which calls
> another one liner. Even with the same number of arguments.
> What is a point of having it? It will never even be extended,
> and does not make the code more compact.
Isn’t it better to SWAP() them in alter_space_do() and alter_space_rollback()
without new class adding?

+/**
+ * Move constraint names hash table from old space to a new one.
+ */
+class MoveConstraintDefs: public AlterSpaceOp
+{
+public:
+	MoveConstraintDefs(struct alter_space *alter) : AlterSpaceOp(alter) {}
+	virtual void alter(struct alter_space *alter);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+MoveConstraintDefs::alter(struct alter_space *alter)
+{
+	SWAP(alter->new_space->constraint_names,
+	     alter->old_space->constraint_names);
+}
+
+void
+MoveConstraintDefs::rollback(struct alter_space *alter)
+{
+	SWAP(alter->new_space->constraint_names,
+	     alter->old_space->constraint_names);
+}
+

>> +}
>> +
>> +void
>> +MoveConstraints::alter(struct alter_space *alter)
>> +{
>> +	space_swap_constraint(alter->old_space, alter->new_space);
>> +}
>> +
>> +void
>> +MoveConstraints::rollback(struct alter_space *alter)
>> +{
>> +	space_swap_constraint(alter->new_space, alter->old_space);
>> +}
>> @@ -2341,6 +2375,150 @@ index_is_used_by_fk_constraint(struct rlist *fk_list, uint32_t iid)
>> +
>> +/**
>> + * Put the node of an unique index to the constraint hash table of
>> + * @a space and create trigger on rollback.
>> + *
>> + * This function is needed to wrap the duplicated piece of code
>> + * inside on_replace_dd_index().
>> + *
>> + * @param stmt  Statement.
>> + * @param space Space.
>> + * @param def   Index def.
>> + *
>> + * @retval 0  Success.
>> + * @retval -1 Constraint already exists or out of memory.
> 
> 4. Once again - please, don't write comments just for
> comments. 'stmt Statement.' really does not make anything
> clearer or easier to understand. Either drop these
> useless formal @param @retval, or provide more *useful*
> details about these arguments. Although I doubt, that
> it is needed. The function is trivial and is not public
> anyway. The same about other similar places.
> 
> The comment's part before first @param is good, keep it.
> 
>> + */
>> +static int
>> +create_index_as_constraint(struct txn_stmt *stmt, struct space *space,
>> +			   struct index_def *def) {
> 
> 5. I propose you to make it `const struct index_def *`.
> 
>> +	assert(def->opts.is_unique);
>> +	if (space_constraint_def_by_name(space, def->name) != NULL) {
>> +		diag_set(ClientError, ER_CONSTRAINT_EXISTS, def->name);
+/**
+ * Put the node of an unique index to the constraint hash table of
+ * @a space.
+ *
+ * This function is needed to wrap the duplicated piece of code
+ * inside on_replace_dd_index().
+ */
+static int
+create_index_as_constraint(struct alter_space *alter,
+			   const struct index_def *def)
+{
+	assert(def->opts.is_unique);
+	struct space *space = alter->old_space;
+	if (space_constraint_def_by_name(space, def->name) != NULL) {
+		diag_set(ClientError, ER_CONSTRAINT_EXISTS, def->name);
+		return -1;
+	}
+	struct constraint_def *constr_def =
+		constraint_def_new(space->def->id, def->iid == 0 ?
+				   CONSTRAINT_TYPE_PK : CONSTRAINT_TYPE_UNIQUE,
+				   def->name);
+	if (constr_def == NULL)
+		return -1;
+	(void) new CreateConstraintDef(alter, constr_def);
+	return 0;
+}
+

> 6. AFAIR, I asked to add constraint type into the error message, didn't I?
> Why didn't you add it?
I have done the commit to the patchset, but IMO, I jumped out of the frying pan
into the fire. Because of, e.g.:

 box.execute("CREATE TABLE t2(id INT PRIMARY KEY, CONSTRAINT fk1 FOREIGN KEY(id) REFERENCES t2, CONSTRAINT fk1 FOREIGN KEY(id) REFERENCES t2);")
 ---
 - null
-- Constraint FK1 already exists
+- Duplicate key exists in unique index 'primary' in space ‘_fk_constraint'

Tuple duplication is checked before the corresponding on_replace_dd_...

>> +		return -1;
>> +	}
>> +	struct constraint_def *constr_def =
>> +		constraint_def_new(space->def->id, def->iid == 0 ?
>> +				   CONSTRAINT_TYPE_PK : CONSTRAINT_TYPE_UNIQUE,
>> +				   def->name);
>> +	if (constr_def == NULL)
>> +		return -1;
>> +	struct trigger *on_rollback = txn_alter_trigger_new(NULL, NULL);
>> +	if (space_put_constraint(space, constr_def) != 0 ||
>> +	    on_rollback == NULL) {
>> +		constraint_def_free(constr_def);
>> +		return -1;
>> +	}
>> +	on_rollback->data = constr_def;
>> +	on_rollback->run = on_create_index_rollback;
>> +	txn_stmt_on_rollback(stmt, on_rollback);
>> +	return 0;
>> +}
>> +
>> +/**
>> + * Drop the node of an unique index from the constraint hash table
>> + * of @a space and create trigger on rollback.
>> + *
>> + * This function is needed to wrap the duplicated piece of code
>> + * inside on_replace_dd_index().
>> + *
>> + * @param stmt  Statement.
>> + * @param space Space.
>> + * @param def   Index def.
>> + *
>> + * @retval 0  Success.
>> + * @retval -1 Out of memory.
>> + */
>> +static int
>> +drop_index_as_constraint(struct txn_stmt *stmt, struct space *space,
>> +			 struct index_def *def) {
>> +	assert(def->opts.is_unique);
>> +	struct constraint_def *constr_def =
>> +		space_constraint_def_by_name(space, def->name);
>> +	assert(constr_def != NULL);
>> +	space_drop_constraint(space, def->name);
>> +	struct trigger *on_rollback = txn_alter_trigger_new(NULL, NULL);
>> +	if (on_rollback == NULL)
>> +		return -1;
> 
> 7. In case on_rollback creation is failed, you don't restore
> the constraint back.
> 
>> +	on_rollback->data = constr_def;
>> +	on_rollback->run = on_drop_index_rollback;
>> +	txn_stmt_on_rollback(stmt, on_rollback);
>> +	return 0;
>> +}
>> +
>> /**
>>  * Just like with _space, 3 major cases:
>>  *> @@ -2469,35 +2645,111 @@ on_replace_dd_index(struct trigger * /* trigger */, void *event)
>> 		 * Can't drop index if foreign key constraints
>> 		 * references this index.
>> 		 */
>> -		if (index_is_used_by_fk_constraint(&old_space->parent_fk_constraint,
>> +		if (index_is_used_by_fk_constraint(&space->parent_fk_constraint,
>> 						   iid)) {
>> -			diag_set(ClientError, ER_ALTER_SPACE,
>> -				  space_name(old_space),
>> +			diag_set(ClientError, ER_ALTER_SPACE, space_name(space),
>> 				  "can not drop a referenced index");
>> 			return -1;
>> 		}
>> 		alter_space_move_indexes(alter, 0, iid);
>> 		(void) new DropIndex(alter, old_index);
>> +		if (old_index->def->opts.is_unique &&
>> +		    drop_index_as_constraint(stmt, space, old_index->def) != 0)
>> +			return -1;
>> 	}
>> 	/* Case 2: create an index, if it is simply created. */
>> 	if (old_index == NULL && new_tuple != NULL) {
>> +		struct index_def *def =
>> +			index_def_new_from_tuple(new_tuple, space);
>> +		if (def == NULL)
>> +			return -1;
>> +		if (def->opts.is_unique) {
>> +			if (create_index_as_constraint(stmt, space, def) != 0) {
>> +				index_def_delete(def);
>> +				return -1;
>> +			}
>> +		}
>> 		alter_space_move_indexes(alter, 0, iid);
>> 		CreateIndex *create_index = new CreateIndex(alter);
>> -		create_index->new_index_def =
>> -			index_def_new_from_tuple(new_tuple, old_space);
>> -		if (create_index->new_index_def == NULL)
>> -			return -1;
>> -		index_def_update_optionality(create_index->new_index_def,
>> -					     alter->new_min_field_count);
>> +		create_index->new_index_def = def;
>> +		index_def_update_optionality(def, alter->new_min_field_count);
>> 	}
>> 	/* Case 3 and 4: check if we need to rebuild index data. */
>> 	if (old_index != NULL && new_tuple != NULL) {
>> 		struct index_def *index_def;
>> -		index_def = index_def_new_from_tuple(new_tuple, old_space);
>> +		index_def = index_def_new_from_tuple(new_tuple, space);
>> 		if (index_def == NULL)
>> 			return -1;
>> 		auto index_def_guard =
>> 			make_scoped_guard([=] { index_def_delete(index_def); });
>> +		struct index_def *old_def = old_index->def;
>> +		/**
> 
> 8. We don't use /** inside functions.
Ok. Removed.

>> +		 * We put a new name either an index is becoming
>> +		 * unique (i.e. constraint), or when an unique
>> +		 * index's name is under change.
>> +		 */
>> +		if (!old_def->opts.is_unique && index_def->opts.is_unique) {
>> +			if (create_index_as_constraint(stmt, space, index_def)
> 
> 9. When you have multiple conditions, it is shorter
> and easier to check them all via && instead of 'if if if ... ‘.
Ok. I thought it was more obvious.

> 
> 13. I remember, you said that 'old_space' -> 'space' is going
> to save some lines, but man. This rename diff is huge. This is
> really comparable with the functional diff in this function. I
> didn't think, that this rename will affect so much code. Please,
> return old_space back. It is not worth introducing such a big
> diff.
Returned.

> 
> 14. Talking of the super mess with on_replace_dd_index, and
> how tight it is now with all these struggling about replacing
> constraints, and on_commit/on_rollback. I think, that this is
> a dead end. Too complex.
> 
> How about introducing a couple of new AlterSpaceOp classes?
> AddConstraint, and DropConstraint. AlterSpaceOp looks good
> because
> - it will allow you to not set on_commit/on_rollback triggers
>  manually - it already provides these methods;
> - you will be able to move this huge pieces of code out of
>  on_replace_dd_index and other on_replace_*;
> - it is consistent with MoveIndex/DropIndex/etc classes.
> 
> All you will need to do is to add to on_replace_*
> (void) new AddConstraint(), and (void) new DropConstraint.
> And you will keep (void) new MoveConstraints().
> 
> Also that should eliminate code duplication between different
> on_replace_* functions about adding/dropping constraints.
+/**
+ * CreateConstraintDef - add a new constraint def to the space.
+ */
+class CreateConstraintDef: public AlterSpaceOp
+{
+private:
+	struct constraint_def *new_constraint_def;
+public:
+	CreateConstraintDef(struct alter_space *alter,
+			    struct constraint_def *def)
+		:AlterSpaceOp(alter), new_constraint_def(def)
+	{}
+	virtual void alter(struct alter_space *alter);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+CreateConstraintDef::alter(struct alter_space *alter)
+{
+	if (space_put_constraint(alter->old_space, new_constraint_def) != 0)
+		panic("Can't recover after constraint alter (out of memory)");
+}
+
+void
+CreateConstraintDef::rollback(struct alter_space *alter)
+{
+	/*
+	 * Pop from new_space, because hash tables was swapped by
+	 * MoveConstraintDefs::alter().
+	 */
+	assert(space_pop_constraint(alter->new_space,
+				    new_constraint_def->name) ==
+	       new_constraint_def);
+	constraint_def_delete(new_constraint_def);
+}
+
+/** DropConstraintDef - drop a constraint def from the space. */
+class DropConstraintDef: public AlterSpaceOp
+{
+private:
+	struct constraint_def *old_constraint_def;
+	const char *name;
+public:
+	DropConstraintDef(struct alter_space *alter, const char *name)
+		:AlterSpaceOp(alter), old_constraint_def(NULL), name(name)
+	{}
+	virtual void alter(struct alter_space *alter);
+	virtual void commit(struct alter_space *alter , int64_t signature);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+DropConstraintDef::alter(struct alter_space *alter)
+{
+	old_constraint_def =
+		space_constraint_def_by_name(alter->old_space, name);
+	assert(old_constraint_def != NULL);
+	space_pop_constraint(alter->old_space, name);
+}
+
+void
+DropConstraintDef::commit(struct alter_space *alter, int64_t signature)
+{
+	(void) alter;
+	(void) signature;
+	constraint_def_delete(old_constraint_def);
+}
+
+void
+DropConstraintDef::rollback(struct alter_space *alter)
+{
+	assert(old_constraint_def != NULL);
+	/*
+	 * Put to new_space, because hash tables was swapped by
+	 * MoveConstraintDefs::alter().
+	 */
+	if (space_put_constraint(alter->new_space, old_constraint_def) != 0) {
+		panic("Can't recover after constraint drop rollback (out of "
+		      "memory)");
+	}
+}
+

commit 5bad13b4756bff553d1107616aa3de3dd4bbe124
Author: Roman Khabibov <roman.habibov@tarantool.org>
Date:   Wed Oct 23 15:54:16 2019 +0300

    sql: make constraint operations transactional
    
    Put constraint names into the space's hash table and drop them on
    replace in corresponding system spaces (_index, _fk_constraint,
    _ck_constraint).
    
    Closes #3503
    
    @TarantoolBot document
    Title: Table constraints in SQL
    
    SQL:
    According to ANSI SQL, table constraint is one of the following
    entities: PRIMARY KEY, UNIQUE, FOREIGN KEY, CHECK. Every
    constraint have its own name passed by user or automatically
    generated. And these names must be unique within one table/space.
    Naming in SQL is case-insensitive, so "CONSTRAINT c" and
    "CONSTRAINT C" are the same. For example, you will get error, if
    you try to:
    
    CREATE TABLE t2 (i INT, CONSTRAINT c CHECK (i > 0),
                     CONSTRAINT c PRIMARY KEY (i));
    
    or
    
    CREATE TABLE t2 (i INT CONSTRAINT c PRIMARY KEY);
    ALTER TABLE t2 ADD CONSTRAINT c CHECK(i > 0);');
    
    The same is for any other constraint types.
    
    Lua/box:
    
    You also can create/drop table constraints from box. See
    space_object:create_check_constraint() and space_object:create_index()
    (if an index is unique). Naming in box is case-sensitive, so 'c' and
    'C' are not the same (see naming policy). For example, an unique
    index is a constraint, but a non-unique index is not. So, a non-unique
    index can have the same name with a check/foreign key constraint
    within one space:
    
    box.execute('CREATE TABLE t2 (i INT PRIMARY KEY);');
    box.execute('CREATE INDEX e ON t2(i);');
    box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
    
    But, if you try to:
    
    box.space.T2.index.E:alter({unique = true});
    
    You will get error, beacuse index 'e' is becoming unique.

diff --git a/src/box/alter.cc b/src/box/alter.cc
index 4a3241a79..9583bfd13 100644
--- a/src/box/alter.cc
+++ b/src/box/alter.cc
@@ -57,6 +57,7 @@
 #include "version.h"
 #include "sequence.h"
 #include "sql.h"
+#include "constraint_def.h"
 
 /* {{{ Auxiliary functions and methods. */
 
@@ -1765,6 +1766,113 @@ MoveCkConstraints::rollback(struct alter_space *alter)
 	space_swap_ck_constraint(alter->new_space, alter->old_space);
 }
 
+/**
+ * CreateConstraintDef - add a new constraint def to the space.
+ */
+class CreateConstraintDef: public AlterSpaceOp
+{
+private:
+	struct constraint_def *new_constraint_def;
+public:
+	CreateConstraintDef(struct alter_space *alter,
+			    struct constraint_def *def)
+		:AlterSpaceOp(alter), new_constraint_def(def)
+	{}
+	virtual void alter(struct alter_space *alter);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+CreateConstraintDef::alter(struct alter_space *alter)
+{
+	if (space_put_constraint(alter->old_space, new_constraint_def) != 0)
+		panic("Can't recover after constraint alter (out of memory)");
+}
+
+void
+CreateConstraintDef::rollback(struct alter_space *alter)
+{
+	/*
+	 * Pop from new_space, because hash tables was swapped by
+	 * MoveConstraintDefs::alter().
+	 */
+	assert(space_pop_constraint(alter->new_space,
+				    new_constraint_def->name) ==
+	       new_constraint_def);
+	constraint_def_delete(new_constraint_def);
+}
+
+/** DropConstraintDef - drop a constraint def from the space. */
+class DropConstraintDef: public AlterSpaceOp
+{
+private:
+	struct constraint_def *old_constraint_def;
+	const char *name;
+public:
+	DropConstraintDef(struct alter_space *alter, const char *name)
+		:AlterSpaceOp(alter), old_constraint_def(NULL), name(name)
+	{}
+	virtual void alter(struct alter_space *alter);
+	virtual void commit(struct alter_space *alter , int64_t signature);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+DropConstraintDef::alter(struct alter_space *alter)
+{
+	old_constraint_def =
+		space_constraint_def_by_name(alter->old_space, name);
+	assert(old_constraint_def != NULL);
+	space_pop_constraint(alter->old_space, name);
+}
+
+void
+DropConstraintDef::commit(struct alter_space *alter, int64_t signature)
+{
+	(void) alter;
+	(void) signature;
+	constraint_def_delete(old_constraint_def);
+}
+
+void
+DropConstraintDef::rollback(struct alter_space *alter)
+{
+	assert(old_constraint_def != NULL);
+	/*
+	 * Put to new_space, because hash tables was swapped by
+	 * MoveConstraintDefs::alter().
+	 */
+	if (space_put_constraint(alter->new_space, old_constraint_def) != 0) {
+		panic("Can't recover after constraint drop rollback (out of "
+		      "memory)");
+	}
+}
+
+/**
+ * Move constraint names hash table from old space to a new one.
+ */
+class MoveConstraintDefs: public AlterSpaceOp
+{
+public:
+	MoveConstraintDefs(struct alter_space *alter) : AlterSpaceOp(alter) {}
+	virtual void alter(struct alter_space *alter);
+	virtual void rollback(struct alter_space *alter);
+};
+
+void
+MoveConstraintDefs::alter(struct alter_space *alter)
+{
+	SWAP(alter->new_space->constraint_names,
+	     alter->old_space->constraint_names);
+}
+
+void
+MoveConstraintDefs::rollback(struct alter_space *alter)
+{
+	SWAP(alter->new_space->constraint_names,
+	     alter->old_space->constraint_names);
+}
+
 /* }}} */
 
 /**
@@ -2307,6 +2415,7 @@ on_replace_dd_space(struct trigger * /* trigger */, void *event)
 		def_guard.is_active = false;
 		/* Create MoveIndex ops for all space indexes. */
 		alter_space_move_indexes(alter, 0, old_space->index_id_max + 1);
+		(void) new MoveConstraintDefs(alter);
 		/* Remember to update schema_version. */
 		(void) new UpdateSchemaVersion(alter);
 		try {
@@ -2341,6 +2450,33 @@ index_is_used_by_fk_constraint(struct rlist *fk_list, uint32_t iid)
 	return false;
 }
 
+/**
+ * Put the node of an unique index to the constraint hash table of
+ * @a space.
+ *
+ * This function is needed to wrap the duplicated piece of code
+ * inside on_replace_dd_index().
+ */
+static int
+create_index_as_constraint(struct alter_space *alter,
+			   const struct index_def *def)
+{
+	assert(def->opts.is_unique);
+	struct space *space = alter->old_space;
+	if (space_constraint_def_by_name(space, def->name) != NULL) {
+		diag_set(ClientError, ER_CONSTRAINT_EXISTS, def->name);
+		return -1;
+	}
+	struct constraint_def *constr_def =
+		constraint_def_new(space->def->id, def->iid == 0 ?
+				   CONSTRAINT_TYPE_PK : CONSTRAINT_TYPE_UNIQUE,
+				   def->name);
+	if (constr_def == NULL)
+		return -1;
+	(void) new CreateConstraintDef(alter, constr_def);
+	return 0;
+}
+
 /**
  * Just like with _space, 3 major cases:
  *
@@ -2476,19 +2612,28 @@ on_replace_dd_index(struct trigger * /* trigger */, void *event)
 				  "can not drop a referenced index");
 			return -1;
 		}
+		struct index_def *def = old_index->def;
 		alter_space_move_indexes(alter, 0, iid);
 		(void) new DropIndex(alter, old_index);
+		if (old_index->def->opts.is_unique)
+			(void) new DropConstraintDef(alter, def->name);
 	}
 	/* Case 2: create an index, if it is simply created. */
 	if (old_index == NULL && new_tuple != NULL) {
-		alter_space_move_indexes(alter, 0, iid);
-		CreateIndex *create_index = new CreateIndex(alter);
-		create_index->new_index_def =
+		struct index_def *def =
 			index_def_new_from_tuple(new_tuple, old_space);
-		if (create_index->new_index_def == NULL)
+		if (def == NULL)
 			return -1;
-		index_def_update_optionality(create_index->new_index_def,
-					     alter->new_min_field_count);
+		if (def->opts.is_unique) {
+			if (create_index_as_constraint(alter, def) != 0) {
+				index_def_delete(def);
+				return -1;
+			}
+		}
+		alter_space_move_indexes(alter, 0, iid);
+		CreateIndex *create_index = new CreateIndex(alter);
+		create_index->new_index_def = def;
+		index_def_update_optionality(def, alter->new_min_field_count);
 	}
 	/* Case 3 and 4: check if we need to rebuild index data. */
 	if (old_index != NULL && new_tuple != NULL) {
@@ -2498,6 +2643,23 @@ on_replace_dd_index(struct trigger * /* trigger */, void *event)
 			return -1;
 		auto index_def_guard =
 			make_scoped_guard([=] { index_def_delete(index_def); });
+		struct index_def *old_def = old_index->def;
+		/*
+		 * We put a new name either an index is becoming
+		 * unique (i.e. constraint), or when an unique
+		 * index's name is under change.
+		 */
+		if (!old_def->opts.is_unique && index_def->opts.is_unique &&
+		    create_index_as_constraint(alter, index_def) != 0)
+				return -1;
+		if (old_def->opts.is_unique && index_def->opts.is_unique &&
+		    strcmp(index_def->name, old_def->name) != 0) {
+			if (create_index_as_constraint(alter, index_def) != 0)
+				return -1;
+			(void) new DropConstraintDef(alter, old_def->name);
+		}
+		if (old_def->opts.is_unique && !index_def->opts.is_unique)
+			(void) new DropConstraintDef(alter, old_def->name);
 		/*
 		 * To detect which key parts are optional,
 		 * min_field_count is required. But
@@ -2572,6 +2734,7 @@ on_replace_dd_index(struct trigger * /* trigger */, void *event)
 	 */
 	alter_space_move_indexes(alter, iid + 1, old_space->index_id_max + 1);
 	(void) new MoveCkConstraints(alter);
+	(void) new MoveConstraintDefs(alter);
 	/* Add an op to update schema_version on commit. */
 	(void) new UpdateSchemaVersion(alter);
 	try {
@@ -2663,6 +2826,7 @@ on_replace_dd_truncate(struct trigger * /* trigger */, void *event)
 	}
 
 	(void) new MoveCkConstraints(alter);
+	(void) new MoveConstraintDefs(alter);
 	try {
 		alter_space_do(stmt, alter);
 	} catch (Exception *e) {
@@ -4951,8 +5115,15 @@ on_create_fk_constraint_rollback(struct trigger *trigger, void *event)
 	struct fk_constraint *fk = (struct fk_constraint *)trigger->data;
 	rlist_del_entry(fk, in_parent_space);
 	rlist_del_entry(fk, in_child_space);
+	struct space *child = space_by_id(fk->def->child_id);
+	const char *name = fk->def->name;
+	struct constraint_def *constr_def =
+		space_constraint_def_by_name(child, name);
+	assert(constr_def != NULL);
+	space_pop_constraint(child, name);
+	constraint_def_delete(constr_def);
 	space_reset_fk_constraint_mask(space_by_id(fk->def->parent_id));
-	space_reset_fk_constraint_mask(space_by_id(fk->def->child_id));
+	space_reset_fk_constraint_mask(child);
 	fk_constraint_delete(fk);
 	return 0;
 }
@@ -4986,11 +5157,24 @@ on_drop_fk_constraint_rollback(struct trigger *trigger, void *event)
 	struct space *child = space_by_id(old_fk->def->child_id);
 	rlist_add_entry(&child->child_fk_constraint, old_fk, in_child_space);
 	rlist_add_entry(&parent->parent_fk_constraint, old_fk, in_parent_space);
+	const char *name = old_fk->def->name;
+	struct constraint_def *constr_def =
+		constraint_def_new(child->def->id, CONSTRAINT_TYPE_FK, name);
+	if (constr_def == NULL)
+		goto panic;
+	if (space_put_constraint(child, constr_def) != 0) {
+		constraint_def_delete(constr_def);
+		goto panic;
+	}
 	fk_constraint_set_mask(old_fk, &child->fk_constraint_mask,
 			       FIELD_LINK_CHILD);
 	fk_constraint_set_mask(old_fk, &parent->fk_constraint_mask,
 			       FIELD_LINK_PARENT);
 	return 0;
+
+panic:
+	panic("Can't recover after FK constraint drop rollback (out of "
+	      "memory)");
 }
 
 /**
@@ -5165,15 +5349,31 @@ on_replace_dd_fk_constraint(struct trigger * /* trigger*/, void *event)
 		fk->def = fk_def;
 		fk->index_id = fk_index->def->iid;
 		if (old_tuple == NULL) {
+			if (space_constraint_def_by_name(child_space,
+							 fk_def->name)
+			    != NULL) {
+				diag_set(ClientError, ER_CONSTRAINT_EXISTS,
+					 fk_def->name);
+				return -1;
+			}
 			rlist_add_entry(&child_space->child_fk_constraint,
 					fk, in_child_space);
 			rlist_add_entry(&parent_space->parent_fk_constraint,
 					fk, in_parent_space);
+			struct constraint_def *constr_def =
+				constraint_def_new(child_space->def->id,
+						   CONSTRAINT_TYPE_FK,
+						   fk_def->name);
+			if (constr_def == NULL)
+				return -1;
 			struct trigger *on_rollback =
 				txn_alter_trigger_new(on_create_fk_constraint_rollback,
 						      fk);
-			if (on_rollback == NULL)
+			if (space_put_constraint(child_space, constr_def) != 0
+			    || on_rollback == NULL) {
+				constraint_def_delete(constr_def);
 				return -1;
+			}
 			txn_stmt_on_rollback(stmt, on_rollback);
 			fk_constraint_set_mask(fk,
 					       &parent_space->fk_constraint_mask,
@@ -5221,6 +5421,12 @@ on_replace_dd_fk_constraint(struct trigger * /* trigger*/, void *event)
 		struct fk_constraint *old_fk=
 			fk_constraint_remove(&child_space->child_fk_constraint,
 					     fk_def->name);
+		const char *name = fk_def->name;
+		struct constraint_def *constr_def =
+			space_constraint_def_by_name(child_space, name);
+		assert(constr_def != NULL);
+		space_pop_constraint(child_space, name);
+		constraint_def_delete(constr_def);
 		struct trigger *on_commit =
 			txn_alter_trigger_new(on_drop_or_replace_fk_constraint_commit,
 					      old_fk);
@@ -5297,9 +5503,14 @@ on_create_ck_constraint_rollback(struct trigger *trigger, void * /* event */)
 	assert(ck != NULL);
 	struct space *space = space_by_id(ck->def->space_id);
 	assert(space != NULL);
-	assert(space_ck_constraint_by_name(space, ck->def->name,
-					   strlen(ck->def->name)) != NULL);
+	const char *name = ck->def->name;
+	assert(space_ck_constraint_by_name(space, name, strlen(name)) != NULL);
 	space_remove_ck_constraint(space, ck);
+	struct constraint_def *constr_def =
+		space_constraint_def_by_name(space, name);
+	assert(constr_def != NULL);
+	space_pop_constraint(space, name);
+	constraint_def_delete(constr_def);
 	ck_constraint_delete(ck);
 	if (trigger_run(&on_alter_space, space) != 0)
 		return -1;
@@ -5324,13 +5535,23 @@ on_drop_ck_constraint_rollback(struct trigger *trigger, void * /* event */)
 	assert(ck != NULL);
 	struct space *space = space_by_id(ck->def->space_id);
 	assert(space != NULL);
-	assert(space_ck_constraint_by_name(space, ck->def->name,
-					   strlen(ck->def->name)) == NULL);
-	if (space_add_ck_constraint(space, ck) != 0)
-		panic("Can't recover after CK constraint drop rollback");
+	const char *name = ck->def->name;
+	assert(space_ck_constraint_by_name(space, name, strlen(name)) == NULL);
+	struct constraint_def *constr_def =
+		constraint_def_new(space->def->id, CONSTRAINT_TYPE_CK, name);
+	if (constr_def == NULL)
+		goto panic;
+	if (space_add_ck_constraint(space, ck) != 0 ||
+	    space_put_constraint(space, constr_def) != 0) {
+		constraint_def_delete(constr_def);
+		goto panic;
+	}
 	if (trigger_run(&on_alter_space, space) != 0)
 		return -1;
 	return 0;
+
+panic:
+	panic("Can't recover after CK constraint drop rollback");
 }
 
 /** Commit REPLACE check constraint. */
@@ -5443,11 +5664,27 @@ on_replace_dd_ck_constraint(struct trigger * /* trigger*/, void *event)
 		auto ck_guard = make_scoped_guard([=] {
 			ck_constraint_delete(new_ck_constraint);
 		});
-		if (old_ck_constraint != NULL)
+		if (old_ck_constraint != NULL) {
 			rlist_del_entry(old_ck_constraint, link);
+		} else if (space_constraint_def_by_name(space, name) != NULL) {
+			diag_set(ClientError, ER_CONSTRAINT_EXISTS,
+				 name);
+			return -1;
+		}
 		if (space_add_ck_constraint(space, new_ck_constraint) != 0)
 			return -1;
 		ck_guard.is_active = false;
+		if (old_ck_constraint == NULL) {
+			struct constraint_def *constr_def =
+				constraint_def_new(space->def->id,
+						   CONSTRAINT_TYPE_CK, name);
+			if (constr_def == NULL)
+				return -1;
+			if (space_put_constraint(space, constr_def) != 0) {
+				constraint_def_delete(constr_def);
+				return -1;
+			}
+		}
 		if (old_tuple != NULL) {
 			on_rollback->data = old_ck_constraint;
 			on_rollback->run = on_replace_ck_constraint_rollback;
@@ -5467,7 +5704,13 @@ on_replace_dd_ck_constraint(struct trigger * /* trigger*/, void *event)
 			return -1;
 		struct ck_constraint *old_ck_constraint =
 			space_ck_constraint_by_name(space, name, name_len);
+		struct constraint_def *constr_def =
+			space_constraint_def_by_name(space,
+						     old_ck_constraint->def->name);
+		assert(constr_def != NULL);
 		assert(old_ck_constraint != NULL);
+		space_pop_constraint(space, old_ck_constraint->def->name);
+		constraint_def_delete(constr_def);
 		space_remove_ck_constraint(space, old_ck_constraint);
 		on_commit->data = old_ck_constraint;
 		on_commit->run = on_drop_ck_constraint_commit;
@@ -5567,6 +5810,7 @@ on_replace_dd_func_index(struct trigger *trigger, void *event)
 	alter_space_move_indexes(alter, index->def->iid + 1,
 				 space->index_id_max + 1);
 	(void) new MoveCkConstraints(alter);
+	(void) new MoveConstraintDefs(alter);
 	(void) new UpdateSchemaVersion(alter);
 	try {
 		alter_space_do(stmt, alter);
diff --git a/test/sql/constraint.result b/test/sql/constraint.result
new file mode 100644
index 000000000..ba262182b
--- /dev/null
+++ b/test/sql/constraint.result
@@ -0,0 +1,190 @@
+-- test-run result file version 2
+test_run = require('test_run').new()
+ | ---
+ | ...
+engine = test_run:get_cfg('engine')
+ | ---
+ | ...
+box.execute('pragma sql_default_engine=\''..engine..'\'')
+ | ---
+ | - row_count: 0
+ | ...
+test_run:cmd("setopt delimiter ';'")
+ | ---
+ | - true
+ | ...
+
+--
+-- Check a constraint name for duplicate within a single
+-- <CREATE TABLE> statement.
+--
+box.execute('CREATE TABLE t1 (i INT PRIMARY KEY);');
+ | ---
+ | - row_count: 1
+ | ...
+box.execute([[CREATE TABLE t2 (i INT, CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c PRIMARY KEY (i));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c PRIMARY KEY (i));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c UNIQUE (i));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c UNIQUE (i));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c CHECK (i < 0));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c CHECK (i > 0));]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY CONSTRAINT c REFERENCES t1(i),
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i))]]);
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+
+--
+-- Check a constraint name for duplicate using <ALTER TABLE>
+-- statement.
+--
+box.execute('CREATE TABLE t2 (i INT CONSTRAINT c PRIMARY KEY);');
+ | ---
+ | - row_count: 1
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c CHECK(i > 0);');
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c UNIQUE(i);');
+ | ---
+ | - null
+ | - Index 'C' already exists in space 'T2'
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i);');
+ | ---
+ | - null
+ | - Constraint C already exists
+ | ...
+
+--
+-- Make sure that a constraint's name isn't kept after the
+-- constraint drop.
+--
+box.execute('CREATE UNIQUE INDEX d ON t2(i);');
+ | ---
+ | - row_count: 1
+ | ...
+box.execute('DROP INDEX d ON t2;');
+ | ---
+ | - row_count: 1
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d CHECK(i > 0);');
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.ck_constraint.D:drop();
+ | ---
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d FOREIGN KEY(i) REFERENCES t1(i);');
+ | ---
+ | - row_count: 1
+ | ...
+box.execute('ALTER TABLE t2 DROP CONSTRAINT d;');
+ | ---
+ | - row_count: 1
+ | ...
+
+--
+-- The same inside a transaction.
+--
+box.begin()
+box.execute('CREATE UNIQUE INDEX d ON t2(i);')
+box.execute('DROP INDEX d ON t2;')
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d CHECK(i > 0);')
+box.space.T2.ck_constraint.D:drop()
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d FOREIGN KEY(i) REFERENCES t1(i);')
+box.execute('ALTER TABLE t2 DROP CONSTRAINT d;')
+box.commit();
+ | ---
+ | ...
+
+--
+-- Make sure, that altering of an index name affect to its record
+-- in the space's constraint hash table.
+--
+box.execute('CREATE UNIQUE INDEX d ON t2(i);');
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.index.D:alter({name = 'E'});
+ | ---
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+ | ---
+ | - null
+ | - Constraint E already exists
+ | ...
+
+--
+-- Make sure, that altering of an index uniqueness puts/drops
+-- its name to/from the space's constraint hash table.
+--
+box.space.T2.index.E:alter({unique = false});
+ | ---
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.index.E:alter({unique = true});
+ | ---
+ | - error: Constraint E already exists
+ | ...
+box.space.T2.ck_constraint.E:drop();
+ | ---
+ | ...
+box.space.T2.index.E:alter({unique = true});
+ | ---
+ | ...
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+ | ---
+ | - null
+ | - Constraint E already exists
+ | ...
+
+-- Alter name and uniqueness of an unique index simultaneously.
+box.space.T2.index.E:alter({name = 'D', unique = false});
+ | ---
+ | ...
+box.execute('CREATE UNIQUE INDEX e ON t2(i);');
+ | ---
+ | - row_count: 1
+ | ...
diff --git a/test/sql/constraint.test.lua b/test/sql/constraint.test.lua
new file mode 100755
index 000000000..50162e47d
--- /dev/null
+++ b/test/sql/constraint.test.lua
@@ -0,0 +1,84 @@
+test_run = require('test_run').new()
+engine = test_run:get_cfg('engine')
+box.execute('pragma sql_default_engine=\''..engine..'\'')
+test_run:cmd("setopt delimiter ';'")
+
+--
+-- Check a constraint name for duplicate within a single
+-- <CREATE TABLE> statement.
+--
+box.execute('CREATE TABLE t1 (i INT PRIMARY KEY);');
+box.execute([[CREATE TABLE t2 (i INT, CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c PRIMARY KEY (i));]]);
+box.execute([[CREATE TABLE t2 (i INT,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c PRIMARY KEY (i));]]);
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c UNIQUE (i));]]);
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c UNIQUE (i));]]);
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c CHECK (i > 0),
+                               CONSTRAINT c CHECK (i < 0));]]);
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY,
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i),
+                               CONSTRAINT c CHECK (i > 0));]]);
+box.execute([[CREATE TABLE t2 (i INT PRIMARY KEY CONSTRAINT c REFERENCES t1(i),
+                               CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i))]]);
+
+--
+-- Check a constraint name for duplicate using <ALTER TABLE>
+-- statement.
+--
+box.execute('CREATE TABLE t2 (i INT CONSTRAINT c PRIMARY KEY);');
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c CHECK(i > 0);');
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c UNIQUE(i);');
+box.execute('ALTER TABLE t2 ADD CONSTRAINT c FOREIGN KEY(i) REFERENCES t1(i);');
+
+--
+-- Make sure that a constraint's name isn't kept after the
+-- constraint drop.
+--
+box.execute('CREATE UNIQUE INDEX d ON t2(i);');
+box.execute('DROP INDEX d ON t2;');
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d CHECK(i > 0);');
+box.space.T2.ck_constraint.D:drop();
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d FOREIGN KEY(i) REFERENCES t1(i);');
+box.execute('ALTER TABLE t2 DROP CONSTRAINT d;');
+
+--
+-- The same inside a transaction.
+--
+box.begin()
+box.execute('CREATE UNIQUE INDEX d ON t2(i);')
+box.execute('DROP INDEX d ON t2;')
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d CHECK(i > 0);')
+box.space.T2.ck_constraint.D:drop()
+box.execute('ALTER TABLE t2 ADD CONSTRAINT d FOREIGN KEY(i) REFERENCES t1(i);')
+box.execute('ALTER TABLE t2 DROP CONSTRAINT d;')
+box.commit();
+
+--
+-- Make sure, that altering of an index name affect to its record
+-- in the space's constraint hash table.
+--
+box.execute('CREATE UNIQUE INDEX d ON t2(i);');
+box.space.T2.index.D:alter({name = 'E'});
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+
+--
+-- Make sure, that altering of an index uniqueness puts/drops
+-- its name to/from the space's constraint hash table.
+--
+box.space.T2.index.E:alter({unique = false});
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+box.space.T2.index.E:alter({unique = true});
+box.space.T2.ck_constraint.E:drop();
+box.space.T2.index.E:alter({unique = true});
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);');
+
+-- Alter name and uniqueness of an unique index simultaneously.
+box.space.T2.index.E:alter({name = 'D', unique = false});
+box.execute('CREATE UNIQUE INDEX e ON t2(i);');