[Tarantool-patches] [PATCH 2/2] sql: support constraint drop

Roman Khabibov roman.habibov at tarantool.org
Sun Feb 16 13:24:16 MSK 2020


Hi! Thanks for the review.

> On Feb 11, 2020, at 19:56, Nikita Pettik <korablev at tarantool.org> wrote:
> 
> On 01 Feb 20:36, Roman Khabibov wrote:
>> Hi! Thanks for the review.
>> 
>>>>>> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
>>>>>> index bc50ecbfa..7c4b5760e 100644
>>>>>> --- a/src/box/sql/build.c
>>>>>> +++ b/src/box/sql/build.c
>>>>>> @@ -1469,6 +1469,29 @@ vdbe_emit_stat_space_clear(struct Parse *parse, const char *stat_table_name,
>>>>>> 	sql_table_delete_from(parse, src_list, where);
>>>>>> @@ -1488,17 +1511,6 @@ vdbe_emit_fk_constraint_drop(struct Parse *parse_context, char *constraint_name,
>>>>>> 	sqlVdbeAddOp4(vdbe, OP_String8, 0, key_reg, 0, constraint_name,
>>>>>> 			  P4_DYNAMIC);
>>>>>> 	sqlVdbeAddOp2(vdbe, OP_Integer, child_id,  key_reg + 1);
>>>>>> -	const char *error_msg =
>>>>>> -		tt_sprintf(tnt_errcode_desc(ER_NO_SUCH_CONSTRAINT),
>>>>>> -			   constraint_name);
>>>>>> -	if (vdbe_emit_halt_with_presence_test(parse_context,
>>>>>> -					      BOX_FK_CONSTRAINT_ID, 0,
>>>>>> -					      key_reg, 2, ER_NO_SUCH_CONSTRAINT,
>>>>>> -					      error_msg, false,
>>>>>> -					      OP_Found) != 0) {
>>>>>> -		sqlDbFree(parse_context->db, constraint_name);
>>>>>> -		return;
>>>>>> -	}
>>>>> 
>>>>> Why did you drop this check?
>>>>> 
>>>>>> 	sqlVdbeAddOp3(vdbe, OP_MakeRecord, key_reg, 2, key_reg + 2);
>>>>>> 	sqlVdbeAddOp2(vdbe, OP_SDelete, BOX_FK_CONSTRAINT_ID, key_reg + 2);
>>>>>> 	VdbeComment((vdbe, "Delete FK constraint %s", constraint_name));
>>>>>> @@ -1523,12 +1535,6 @@ vdbe_emit_ck_constraint_drop(struct Parse *parser, const char *ck_name,
>>>>>> 	sqlVdbeAddOp2(v, OP_Integer, space_id,  key_reg);
>>>>>> 	sqlVdbeAddOp4(v, OP_String8, 0, key_reg + 1, 0,
>>>>>> 		      sqlDbStrDup(db, ck_name), P4_DYNAMIC);
>>>>>> -	const char *error_msg =
>>>>>> -		tt_sprintf(tnt_errcode_desc(ER_NO_SUCH_CONSTRAINT), ck_name);
>>>>>> -	if (vdbe_emit_halt_with_presence_test(parser, BOX_CK_CONSTRAINT_ID, 0,
>>>>>> -					      key_reg, 2, ER_NO_SUCH_CONSTRAINT,
>>>>>> -					      error_msg, false, OP_Found) != 0)
>>>>>> -		return;
>>>>> 
>>>>> Same question.
>>>> I dropped these checks, because I thought that the data are consistent. These two
>>>> functions are called when:
>>>> 1) DROP TABLE. If the constraint exist in struct space, then the corresponding tuple
>>>> exists in _ck/_fk system space too. Therefore this error can not occur in box.
>>>> 
>>>> 2) ALTER TABLE DROP CONSTRAINT. Analogically, I check the constraint for existence in
>>>> sql_drop_constraint() and throw error on parsing level.
>>> 
>>> Data can be consistent at the parsing stage, but be inconsistent during
>>> execution. Especially taking into account 'prepare' mechanism having
>>> been recently introduced. So please put these checks back.
>> Done.
> 
> In sql_drop_constraint() in index dropping branch there's still no
> vdbe_emit_halt_with_presence_test() call. Please add it there as well.
+	case CONSTRAINT_TYPE_PK:
+	case CONSTRAINT_TYPE_UNIQUE: {
+		uint32_t index_id = box_index_id_by_name(space->def->id, name,
+							 strlen(name));
+		/*
+		 * We have already verified, that this index
+		 * exists, so we don't check index_id for
+		 * BOX_ID_NIL.
+		 */
+		assert(index_id != BOX_ID_NIL);
+		int record_reg = ++parse_context->nMem;
+		int space_id_reg = ++parse_context->nMem;
+		int index_id_reg = ++parse_context->nMem;
+		sqlVdbeAddOp2(v, OP_Integer, space->def->id, space_id_reg);
+		sqlVdbeAddOp2(v, OP_Integer, index_id, index_id_reg);
+		const char *error_msg =
+			tt_sprintf(tnt_errcode_desc(ER_NO_SUCH_CONSTRAINT),
+				   id->name, space->def->name);
+		if (vdbe_emit_halt_with_presence_test(parse_context,
+						      BOX_INDEX_ID, 0,
+						      space_id_reg, 2,
+						      ER_NO_SUCH_CONSTRAINT,
+						      error_msg, false,
+						      OP_Found) != 0)
+			return;
+		sqlVdbeAddOp3(v, OP_MakeRecord, space_id_reg, 2, record_reg);
+		sqlVdbeAddOp2(v, OP_SDelete, BOX_INDEX_ID, record_reg);
+		break;
+	}

>> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
>> index d9bf8de91..27963c455 100644
>> --- a/src/box/sql/build.c
>> +++ b/src/box/sql/build.c
>> @@ -2052,35 +2052,74 @@ fk_constraint_change_defer_mode(struct Parse *parse_context, bool is_deferred)
>> 		is_deferred;
>> }
>> 
>> +/**
>> + * Emit code to drop the entry from _index or _ck_contstraint or
>> + * _fk_constraint space corresponding with the constraint type.
>> + */
> 
> As a rule we place comments near function declaration.
 /**
+ * Emit code to drop the entry from _index or _ck_contstraint or
+ * _fk_constraint space corresponding with the constraint type.
+ *
  * Function called from parser to handle
  * <ALTER TABLE table DROP CONSTRAINT constraint> SQL statement.
  *
  * @param parse_context Parsing context.
  */
 void
-sql_drop_foreign_key(struct Parse *parse_context);
+sql_drop_constraint(struct Parse *parse_context);

>> void
>> -sql_drop_foreign_key(struct Parse *parse_context)
>> +sql_drop_constraint(struct Parse *parse_context)
>> {
>> 	}
>> -	vdbe_emit_fk_constraint_drop(parse_context, constraint_name,
>> -				     child->def);
>> +	struct Vdbe *v = sqlGetVdbe(parse_context);
>> +	assert(v != NULL);
>> +	assert(id->type < constraint_type_MAX);
>> +	switch (id->type) {
>> +	case CONSTRAINT_TYPE_PK:
>> +	case CONSTRAINT_TYPE_UNIQUE: {
>> +		uint32_t index_id = box_index_id_by_name(space->def->id, name,
>> +							 strlen(name));
>> +		/*
>> +		 * We have already verified, that this index
>> +		 * exists, so we don't check index_id for
>> +		 * BOX_ID_NIL.
>> +		 */
>> +		assert(index_id != BOX_ID_NIL);
>> +		int record_reg = ++parse_context->nMem;
>> +		int space_id_reg = ++parse_context->nMem;
>> +		int index_id_reg = ++parse_context->nMem;
>> +		sqlVdbeAddOp2(v, OP_Integer, space->def->id, space_id_reg);
>> +		sqlVdbeAddOp2(v, OP_Integer, index_id, index_id_reg);
>> +		sqlVdbeAddOp3(v, OP_MakeRecord, space_id_reg, 2, record_reg);
>> +		sqlVdbeAddOp2(v, OP_SDelete, BOX_INDEX_ID, record_reg);
>> +		break;
>> +	}
>> +	case CONSTRAINT_TYPE_FK:
>> +		vdbe_emit_fk_constraint_drop(parse_context, name, space->def);
>> +		break;
>> +	case CONSTRAINT_TYPE_CK:
>> +		vdbe_emit_ck_constraint_drop(parse_context, name, space->def);
>> +		break;
>> +	default:
>> +		unreachable();
>> +	}
>> 	/*
>> 	 * We account changes to row count only if drop of
>> -	 * foreign keys take place in a separate
>> -	 * ALTER TABLE DROP CONSTRAINT statement, since whole
>> -	 * DROP TABLE always returns 1 (one) as a row count.
>> +	 * constraints take place in a separate ALTER TABLE DROP
>> +	 * CONSTRAINT statement, since whole DROP TABLE always
>> +	 * returns 1 (one) as a row count.
>> 	 */
> 
> This comment doesn't look like related to this function:
> sql_drop_constraint() is never called within drop table statement.
Dropped.

>> -	struct Vdbe *v = sqlGetVdbe(parse_context);
>> 	sqlVdbeCountChanges(v);
>> 	sqlVdbeChangeP5(v, OPFLAG_NCHANGE);
>> }
>> diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
>> index cfe1c0012..1a0e89703 100644
>> --- a/src/box/sql/parse.y
>> +++ b/src/box/sql/parse.y
>> @@ -1763,9 +1763,9 @@ cmd ::= alter_table_start(A) RENAME TO nm(N). {
>> }
>> 
>> cmd ::= ALTER TABLE fullname(X) DROP CONSTRAINT nm(Z). {
>> -  drop_fk_def_init(&pParse->drop_fk_def, X, &Z, false);
>> +  drop_constraint_def_init(&pParse->drop_constraint_def, X, &Z, false);
>>   pParse->initiateTTrans = true;
>> -  sql_drop_foreign_key(pParse);
>> +  sql_drop_constraint(pParse);
>> }
>> 
>> cmd ::= alter_table_start(A) enable(E) CHECK CONSTRAINT nm(Z). {
>> diff --git a/src/box/sql/parse_def.h b/src/box/sql/parse_def.h
>> index 2f433e4c0..e6d45b256 100644
>> --- a/src/box/sql/parse_def.h
>> +++ b/src/box/sql/parse_def.h
>> @@ -159,10 +159,6 @@ enum entity_type {
>> 	ENTITY_TYPE_TRIGGER,
>> 	ENTITY_TYPE_CK,
>> 	ENTITY_TYPE_FK,
>> -	/**
>> -	 * For assertion checks that constraint definition is
>> -	 * created before initialization of a term constraint.
>> -	 */
> 
> Why did you drop this comment?
Returned. I mistakenly thought, that it isn’t only for asserts.

commit 490b34dacc19cb9ea7fc36f52dec023fb20d1b3b
Author: Roman Khabibov <roman.habibov at tarantool.org>
Date:   Thu Jan 2 20:13:36 2020 +0300

    sql: support constraint drop
    
    Extend <ALTER TABLE> statement to drop table constraints by their
    names.
    
    Closes #4120
    
    @TarantoolBot document
    Title: Drop table constraints in SQL
    Now, it is possible to drop table constraints (PRIMARY KEY,
    UNIQUE, FOREIGN KEY, CHECK) using
    <ALTER TABLE table_name DROP CONSTRAINT constraint_name> statement
    by their names.
    
    For example:
    
    tarantool> box.execute([[CREATE TABLE test (
                                 a INTEGER PRIMARY KEY,
                                 b INTEGER,
                                 CONSTRAINT cnstr CHECK (a >= 0)
                            );]])
    ---
    - row_count: 1
    ...
    
    tarantool> box.execute('ALTER TABLE test DROP CONSTRAINT cnstr;')
    ---
    - row_count: 1
    ...
    
    The same for all the other constraints.

diff --git a/src/box/constraint_id.h b/src/box/constraint_id.h
index 21f067cdc..ed4f37426 100755
--- a/src/box/constraint_id.h
+++ b/src/box/constraint_id.h
@@ -40,6 +40,7 @@ enum constraint_type {
 	CONSTRAINT_TYPE_UNIQUE,
 	CONSTRAINT_TYPE_FK,
 	CONSTRAINT_TYPE_CK,
+	constraint_type_MAX,
 };
 
 extern const char *constraint_type_strs[];
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index d9bf8de91..76ad79350 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -2052,35 +2052,78 @@ fk_constraint_change_defer_mode(struct Parse *parse_context, bool is_deferred)
 		is_deferred;
 }
 
+/**
+ * Emit code to drop the entry from _index or _ck_contstraint or
+ * _fk_constraint space corresponding with the constraint type.
+ */
 void
-sql_drop_foreign_key(struct Parse *parse_context)
+sql_drop_constraint(struct Parse *parse_context)
 {
-	struct drop_entity_def *drop_def = &parse_context->drop_fk_def.base;
-	assert(drop_def->base.entity_type == ENTITY_TYPE_FK);
+	struct drop_entity_def *drop_def =
+		&parse_context->drop_constraint_def.base;
+	assert(drop_def->base.entity_type == ENTITY_TYPE_CONSTRAINT);
 	assert(drop_def->base.alter_action == ALTER_ACTION_DROP);
 	const char *table_name = drop_def->base.entity_name->a[0].zName;
 	assert(table_name != NULL);
-	struct space *child = space_by_name(table_name);
-	if (child == NULL) {
+	struct space *space = space_by_name(table_name);
+	if (space == NULL) {
 		diag_set(ClientError, ER_NO_SUCH_SPACE, table_name);
 		parse_context->is_aborted = true;
 		return;
 	}
-	char *constraint_name =
-		sql_name_from_token(parse_context->db, &drop_def->name);
-	if (constraint_name == NULL) {
+	char *name = sql_name_from_token(parse_context->db, &drop_def->name);
+	if (name == NULL) {
+		parse_context->is_aborted = true;
+		return;
+	}
+	struct constraint_id *id = space_find_constraint_id(space, name);
+	if (id == NULL) {
+		diag_set(ClientError, ER_NO_SUCH_CONSTRAINT, name, table_name);
 		parse_context->is_aborted = true;
 		return;
 	}
-	vdbe_emit_fk_constraint_drop(parse_context, constraint_name,
-				     child->def);
-	/*
-	 * We account changes to row count only if drop of
-	 * foreign keys take place in a separate
-	 * ALTER TABLE DROP CONSTRAINT statement, since whole
-	 * DROP TABLE always returns 1 (one) as a row count.
-	 */
 	struct Vdbe *v = sqlGetVdbe(parse_context);
+	assert(v != NULL);
+	assert(id->type < constraint_type_MAX);
+	switch (id->type) {
+	case CONSTRAINT_TYPE_PK:
+	case CONSTRAINT_TYPE_UNIQUE: {
+		uint32_t index_id = box_index_id_by_name(space->def->id, name,
+							 strlen(name));
+		/*
+		 * We have already verified, that this index
+		 * exists, so we don't check index_id for
+		 * BOX_ID_NIL.
+		 */
+		assert(index_id != BOX_ID_NIL);
+		int record_reg = ++parse_context->nMem;
+		int space_id_reg = ++parse_context->nMem;
+		int index_id_reg = ++parse_context->nMem;
+		sqlVdbeAddOp2(v, OP_Integer, space->def->id, space_id_reg);
+		sqlVdbeAddOp2(v, OP_Integer, index_id, index_id_reg);
+		const char *error_msg =
+			tt_sprintf(tnt_errcode_desc(ER_NO_SUCH_CONSTRAINT),
+				   id->name, space->def->name);
+		if (vdbe_emit_halt_with_presence_test(parse_context,
+						      BOX_INDEX_ID, 0,
+						      space_id_reg, 2,
+						      ER_NO_SUCH_CONSTRAINT,
+						      error_msg, false,
+						      OP_Found) != 0)
+			return;
+		sqlVdbeAddOp3(v, OP_MakeRecord, space_id_reg, 2, record_reg);
+		sqlVdbeAddOp2(v, OP_SDelete, BOX_INDEX_ID, record_reg);
+		break;
+	}
+	case CONSTRAINT_TYPE_FK:
+		vdbe_emit_fk_constraint_drop(parse_context, name, space->def);
+		break;
+	case CONSTRAINT_TYPE_CK:
+		vdbe_emit_ck_constraint_drop(parse_context, name, space->def);
+		break;
+	default:
+		unreachable();
+	}
 	sqlVdbeCountChanges(v);
 	sqlVdbeChangeP5(v, OPFLAG_NCHANGE);
 }
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index cfe1c0012..1a0e89703 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -1763,9 +1763,9 @@ cmd ::= alter_table_start(A) RENAME TO nm(N). {
 }
 
 cmd ::= ALTER TABLE fullname(X) DROP CONSTRAINT nm(Z). {
-  drop_fk_def_init(&pParse->drop_fk_def, X, &Z, false);
+  drop_constraint_def_init(&pParse->drop_constraint_def, X, &Z, false);
   pParse->initiateTTrans = true;
-  sql_drop_foreign_key(pParse);
+  sql_drop_constraint(pParse);
 }
 
 cmd ::= alter_table_start(A) enable(E) CHECK CONSTRAINT nm(Z). {
diff --git a/src/box/sql/parse_def.h b/src/box/sql/parse_def.h
index 2f433e4c0..cb0ecd2fc 100644
--- a/src/box/sql/parse_def.h
+++ b/src/box/sql/parse_def.h
@@ -265,7 +265,7 @@ struct drop_trigger_def {
 	struct drop_entity_def base;
 };
 
-struct drop_fk_def {
+struct drop_constraint_def {
 	struct drop_entity_def base;
 };
 
@@ -408,11 +408,12 @@ drop_trigger_def_init(struct drop_trigger_def *drop_trigger_def,
 }
 
 static inline void
-drop_fk_def_init(struct drop_fk_def *drop_fk_def, struct SrcList *parent_name,
-		 struct Token *name, bool if_exist)
+drop_constraint_def_init(struct drop_constraint_def *drop_constraint_def,
+			 struct SrcList *parent_name, struct Token *name,
+			 bool if_exist)
 {
-	drop_entity_def_init(&drop_fk_def->base, parent_name, name, if_exist,
-			     ENTITY_TYPE_FK);
+	drop_entity_def_init(&drop_constraint_def->base, parent_name, name,
+			     if_exist, ENTITY_TYPE_CONSTRAINT);
 }
 
 static inline void
diff --git a/src/box/sql/sqlInt.h b/src/box/sql/sqlInt.h
index d1fcf4761..1579cc92e 100644
--- a/src/box/sql/sqlInt.h
+++ b/src/box/sql/sqlInt.h
@@ -2237,7 +2237,7 @@ struct Parse {
 		struct create_trigger_def create_trigger_def;
 		struct create_view_def create_view_def;
 		struct rename_entity_def rename_entity_def;
-		struct drop_fk_def drop_fk_def;
+		struct drop_constraint_def drop_constraint_def;
 		struct drop_index_def drop_index_def;
 		struct drop_table_def drop_table_def;
 		struct drop_trigger_def drop_trigger_def;
@@ -3741,13 +3741,16 @@ void
 sql_create_foreign_key(struct Parse *parse_context);
 
 /**
+ * Emit code to drop the entry from _index or _ck_contstraint or
+ * _fk_constraint space corresponding with the constraint type.
+ *
  * Function called from parser to handle
  * <ALTER TABLE table DROP CONSTRAINT constraint> SQL statement.
  *
  * @param parse_context Parsing context.
  */
 void
-sql_drop_foreign_key(struct Parse *parse_context);
+sql_drop_constraint(struct Parse *parse_context);
 
 /**
  * Now our SQL implementation can't operate on spaces which
diff --git a/test/sql/constraint.result b/test/sql/constraint.result
index 1585c2327..2847fe8ef 100644
--- a/test/sql/constraint.result
+++ b/test/sql/constraint.result
@@ -291,6 +291,67 @@ box.execute('CREATE UNIQUE INDEX d ON t2(i);')
  | - Index 'D' already exists in space 'T2'
  | ...
 
+--
+-- gh-4120: Ensure that <ALTER TABLE DROP CONSTRAINT> works
+-- correctly for each type of constraint.
+--
+-- Drop UNIQUE constraint.
+box.space.T2.index.E ~= nil
+ | ---
+ | - true
+ | ...
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.index.E == nil
+ | ---
+ | - true
+ | ...
+-- Drop PRIMARY KEY constraint named "C".
+box.execute('DROP INDEX d ON t2;')
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.index.C ~= nil
+ | ---
+ | - true
+ | ...
+box.execute('ALTER TABLE t2 DROP CONSTRAINT c;')
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.index.C == nil
+ | ---
+ | - true
+ | ...
+-- Drop CHECK constraint.
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);')
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.ck_constraint.E ~= nil
+ | ---
+ | - true
+ | ...
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+ | ---
+ | - row_count: 1
+ | ...
+box.space.T2.ck_constraint.E == nil
+ | ---
+ | - true
+ | ...
+-- Drop FOREIGN KEY constraint.
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e FOREIGN KEY(i) REFERENCES t1(i);')
+ | ---
+ | - row_count: 1
+ | ...
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+ | ---
+ | - row_count: 1
+ | ...
+
 --
 -- Cleanup.
 --
diff --git a/test/sql/constraint.test.lua b/test/sql/constraint.test.lua
index 163f4309c..12f673dac 100755
--- a/test/sql/constraint.test.lua
+++ b/test/sql/constraint.test.lua
@@ -131,6 +131,28 @@ box.execute('CREATE UNIQUE INDEX e ON t2(i);')
 -- uniqueness, index names should be unique in a space.
 box.execute('CREATE UNIQUE INDEX d ON t2(i);')
 
+--
+-- gh-4120: Ensure that <ALTER TABLE DROP CONSTRAINT> works
+-- correctly for each type of constraint.
+--
+-- Drop UNIQUE constraint.
+box.space.T2.index.E ~= nil
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+box.space.T2.index.E == nil
+-- Drop PRIMARY KEY constraint named "C".
+box.execute('DROP INDEX d ON t2;')
+box.space.T2.index.C ~= nil
+box.execute('ALTER TABLE t2 DROP CONSTRAINT c;')
+box.space.T2.index.C == nil
+-- Drop CHECK constraint.
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e CHECK(i > 0);')
+box.space.T2.ck_constraint.E ~= nil
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+box.space.T2.ck_constraint.E == nil
+-- Drop FOREIGN KEY constraint.
+box.execute('ALTER TABLE t2 ADD CONSTRAINT e FOREIGN KEY(i) REFERENCES t1(i);')
+box.execute('ALTER TABLE t2 DROP CONSTRAINT e;')
+
 --
 -- Cleanup.
 --





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