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From: Alex Khatskevich <avkhatskevich@tarantool.org>
To: "n.pettik" <korablev@tarantool.org>, tarantool-patches@freelists.org
Subject: [tarantool-patches] Re: [PATCH] sql: fix fk set null clause
Date: Thu, 11 Oct 2018 16:20:25 +0300	[thread overview]
Message-ID: <1c7c98dc-99ee-1f2b-7996-83bdd4e1c6ee@tarantool.org> (raw)
In-Reply-To: <EED4050D-A55A-4E87-A7F7-AAD19BC8131A@tarantool.org>


>> After changing behavior of the `IS` operator (#b3a3ddb571),
>> `SET NULL` was rewritten to use `EQ` instead. Which do not respect
> Nit: doesn’t.
fixed
>> NULLs.
>>
>> This commit fixes the null related behavior by emitting logical
>> constructions equivalent for this case to old `IS`.
>> Those constructions are not equal to the old `EQ` in common case.
>> Before:
>> `oldval` old_is `newval`
>> Now:
>> `oldval` is_null or (`newval` is_not_null and `oldval` eq `newval`)
> I guess it is not completely correct: if oldval == NULL and newval != NULL,
> than ‘before’ condition will be false, but ’now’ will be true. Did I miss smth?
Yes. Those are equivalent for that particular case. I slightly updated 
the comment.
New comment:
====
This commit fixes the null related behavior by emitting logical
constructions equivalent for this case to old `IS`.
The new expression works differently than old `IS` for nulls, however
the difference doesn't change anything, because matched rows are then
searched in a child table with `EQ` expression which do not match nulls.
Before:
`oldval` old_is `newval`
Now:
`oldval` is_null or (`newval` is_not_null and `oldval` eq `newval`)
=====
>> Closes #3645
>> ---
>> Issue: https://github.com/tarantool/tarantool/issues/3645
>> Branch: https://github.com/tarantool/tarantool/tree/kh/gh-3642-set-null
>>
>> src/box/sql/fkey.c                    | 49 ++++++++++++++------
>> test/sql-tap/gh3645-set-null.test.lua | 84 +++++++++++++++++++++++++++++++++++
>> 2 files changed, 119 insertions(+), 14 deletions(-)
>> create mode 100755 test/sql-tap/gh3645-set-null.test.lua
>>
>> diff --git a/src/box/sql/fkey.c b/src/box/sql/fkey.c
>> index 091778fc8..0abf42c84 100644
>> --- a/src/box/sql/fkey.c
>> +++ b/src/box/sql/fkey.c
>> @@ -787,24 +787,45 @@ fkey_action_trigger(struct Parse *pParse, struct Table *pTab, struct fkey *fkey,
>>
>> 		/*
>> 		 * For ON UPDATE, construct the next term of the
>> -		 * WHEN clause. The final WHEN clause will be like
>> +		 * WHEN clause, which should return false in case
>> +		 * there is a reason to for a broken constrant in
>> +		 * a parent table:
>> +		 *     no_action_needed := `oldval` IS NULL OR
>> +		 *         (`newval` IS NOT NULL AND
>> +		 *             `newval` = `oldval`)
>> +		 *
>> +		 * The final WHEN clause will be like
>> 		 * this:
>> 		 *
>> -		 *    WHEN NOT(old.col1 = new.col1 AND ... AND
>> -		 *             old.colN = new.colN)
>> +		 *    WHEN NOT( no_action_needed(col1) AND ...
>> +		 *        no_action_needed(colN))
>> 		 */
>> 		if (is_update) {
>> -			struct Expr *l, *r;
>> -			l = sqlite3PExpr(pParse, TK_DOT,
>> -					 sqlite3ExprAlloc(db, TK_ID, &t_old, 0),
>> -					 sqlite3ExprAlloc(db, TK_ID, &t_to_col,
>> -							  0));
>> -			r = sqlite3PExpr(pParse, TK_DOT,
>> -					 sqlite3ExprAlloc(db, TK_ID, &t_new, 0),
>> -					 sqlite3ExprAlloc(db, TK_ID, &t_to_col,
>> -							  0));
>> -			eq = sqlite3PExpr(pParse, TK_EQ, l, r);
>> -			when = sqlite3ExprAnd(db, when, eq);
>> +			Expr *old_val = sqlite3PExpr(
> Nit: struct Expr *...
>
>> +				pParse, TK_DOT,
>> +				sqlite3ExprAlloc(db, TK_ID, &t_old, 0),
>> +				sqlite3ExprAlloc(db, TK_ID, &t_to_col,
>> +						 0));
>> +			Expr *newVal = sqlite3PExpr(
> Nit: struct Expr new_val = …
> And use everywhere else ‘struct' prefix.
>
>> +				pParse, TK_DOT,
>> +				sqlite3ExprAlloc(db, TK_ID, &t_new, 0),
>> +				sqlite3ExprAlloc(db, TK_ID, &t_to_col,
>> +						 0));
>> +			Expr *old_is_null = sqlite3PExpr(
>> +				pParse, TK_ISNULL,
>> +				sqlite3ExprDup(db, old_val, 0), NULL);
>> +			eq = sqlite3PExpr(
>> +				pParse, TK_EQ,
>> +				sqlite3ExprDup(db, old_val, 0),
>> +				sqlite3ExprDup(db, newVal, 0));
>> +			Expr *new_non_null = sqlite3PExpr(
>> +				pParse, TK_NOTNULL, newVal, NULL);
>> +			Expr *non_null_eq = sqlite3PExpr(
>> +				pParse, TK_AND, new_non_null, eq);
>> +			Expr *no_action_needed = sqlite3PExpr(
>> +				pParse, TK_OR, old_is_null,
>> +				non_null_eq);
>> +			when = sqlite3ExprAnd(db, when, no_action_needed);
> How memory for old_val will be released? It’s twice dupped, but original
> value will be not freed. new_val is once dupped and once used, for example.
> I guess it looks like leak.
Yes, it is.
>
> Overall, I suggest cosmetic diff (indentation + struct prefixes):
>
> +++ b/src/box/sql/fkey.c
> @@ -801,30 +801,24 @@ fkey_action_trigger(struct Parse *pParse, struct Table *pTab, struct fkey *fkey,
>                   *        no_action_needed(colN))
>                   */
>                  if (is_update) {
> -                       Expr *old_val = sqlite3PExpr(
> -                               pParse, TK_DOT,
> +                       struct Expr *old_val = sqlite3PExpr(pParse, TK_DOT,
>                                  sqlite3ExprAlloc(db, TK_ID, &t_old, 0),
> -                               sqlite3ExprAlloc(db, TK_ID, &t_to_col,
> -                                                0));
> -                       Expr *newVal = sqlite3PExpr(
> -                               pParse, TK_DOT,
> +                               sqlite3ExprAlloc(db, TK_ID, &t_to_col, 0));
> +                       struct Expr *new_val = sqlite3PExpr(pParse, TK_DOT,
>                                  sqlite3ExprAlloc(db, TK_ID, &t_new, 0),
> -                               sqlite3ExprAlloc(db, TK_ID, &t_to_col,
> -                                                0));
> -                       Expr *old_is_null = sqlite3PExpr(
> -                               pParse, TK_ISNULL,
> +                               sqlite3ExprAlloc(db, TK_ID, &t_to_col, 0));
> +                       struct Expr *old_is_null = sqlite3PExpr(pParse, TK_ISNULL,
>                                  sqlite3ExprDup(db, old_val, 0), NULL);
> -                       eq = sqlite3PExpr(
> -                               pParse, TK_EQ,
> -                               sqlite3ExprDup(db, old_val, 0),
> -                               sqlite3ExprDup(db, newVal, 0));
> -                       Expr *new_non_null = sqlite3PExpr(
> -                               pParse, TK_NOTNULL, newVal, NULL);
> -                       Expr *non_null_eq = sqlite3PExpr(
> -                               pParse, TK_AND, new_non_null, eq);
> -                       Expr *no_action_needed = sqlite3PExpr(
> -                               pParse, TK_OR, old_is_null,
> -                               non_null_eq);
> +                       eq = sqlite3PExpr(pParse, TK_EQ,
> +                                         sqlite3ExprDup(db, old_val, 0),
> +                                         sqlite3ExprDup(db, new_val, 0));
> +                       struct Expr *new_non_null =
> +                               sqlite3PExpr(pParse, TK_NOTNULL, new_val, NULL);
> +                       struct Expr *non_null_eq =
> +                               sqlite3PExpr(pParse, TK_AND, new_non_null, eq);
> +                       struct Expr *no_action_needed =
> +                               sqlite3PExpr(pParse, TK_OR, old_is_null,
> +                                            non_null_eq);
applied.
>> 		}
>>
>> 		if (action != FKEY_ACTION_RESTRICT &&
>> diff --git a/test/sql-tap/gh3645-set-null.test.lua b/test/sql-tap/gh3645-set-null.test.lua
>> new file mode 100755
>> index 000000000..9067c52f1
>> --- /dev/null
>> +++ b/test/sql-tap/gh3645-set-null.test.lua
> I wouldn’t create separate test-file for this ticket: you could
> use one of fkey1-4 test suites.
moved
>
>> @@ -0,0 +1,84 @@
>> +#!/usr/bin/env tarantool
>> +test = require("sqltester")
>> +test:plan(11)
>> +
>> +test:do_catchsql_test(
>> +	"set-null-1.0",
>> +	[[
>> +		CREATE TABLE T1 (a INTEGER PRIMARY KEY,
>> +            b char(5) unique);
>> +		CREATE TABLE T2 (a INTEGER PRIMARY KEY,
>> +            b char(5) unique,
>> +            foreign key (b) references t1 (b) on update set null);
> Nit: use uppercase for SQL keywords.
done
>
>> +        INSERT INTO T1 VALUES (1,'a');
>> +        INSERT INTO T2 VALUES (1,'a’);
> Nit: indentation is broken.
fixed
>
>> +	]], {0});
>> +
>> +test:do_catchsql_test(
>> +	"set-null-1.1",
>> +	[[
>> +        UPDATE T1 SET B = NULL;
>> +	]], {0});
>> +
>> +test:do_catchsql_test(
> Why do you use catchsql? I guess execsql would be more suitable here
> and for the rest tests as well (except for UPDATE statements).
fixed
>
>> +test:do_catchsql_test(
>> +	"set-null-2.0",
>> +	[[
>> +		CREATE TABLE T3 (a INTEGER PRIMARY KEY,
>> +            b char(5) unique);
>> +		CREATE TABLE T4 (a INTEGER PRIMARY KEY,
>> +            b char(5) unique,
>> +            foreign key (b) references t3 (b) on update cascade);
>> +        INSERT INTO T3 VALUES (1,'a');
>> +        INSERT INTO T4 VALUES (1,'a');
>> +	]], {0});
> Indentation is broken.
> How ‘ON UPDATE CASCADE’ clause is related to ’SET NULL’?
Not related. Similar test exists. Deleted.

New diff:

commit 77d76c1c664f992efc54b5a3329a44a185b1e4cf
Author: AKhatskevich <avkhatskevich@tarantool.org>
Date:   Mon Oct 8 19:26:59 2018 +0300

     sql: fix fk set null clause

     After changing behavior of the `IS` operator (#b3a3ddb571),
     `SET NULL` was rewritten to use `EQ` instead. Which doesn't respect
     NULLs.

     This commit fixes the null related behavior by emitting logical
     constructions equivalent for this case to old `IS`.
     The new expression works differently than old `IS` for nulls, however
     the difference doesn't change anything, because matched rows are then
     searched in a child table with `EQ` expression which do not match 
nulls.
     Before:
     `oldval` old_is `newval`
     Now:
     `oldval` is_null or (`newval` is_not_null and `oldval` eq `newval`)

     Closes #3645

diff --git a/src/box/sql/fkey.c b/src/box/sql/fkey.c
index 091778fc8..56885e448 100644
--- a/src/box/sql/fkey.c
+++ b/src/box/sql/fkey.c
@@ -787,24 +787,39 @@ fkey_action_trigger(struct Parse *pParse, struct 
Table *pTab, struct fkey *fkey,

          /*
           * For ON UPDATE, construct the next term of the
-         * WHEN clause. The final WHEN clause will be like
+         * WHEN clause, which should return false in case
+         * there is a reason to for a broken constrant in
+         * a parent table:
+         *     no_action_needed := `oldval` IS NULL OR
+         *         (`newval` IS NOT NULL AND
+         *             `newval` = `oldval`)
+         *
+         * The final WHEN clause will be like
           * this:
           *
-         *    WHEN NOT(old.col1 = new.col1 AND ... AND
-         *             old.colN = new.colN)
+         *    WHEN NOT( no_action_needed(col1) AND ...
+         *        no_action_needed(colN))
           */
          if (is_update) {
-            struct Expr *l, *r;
-            l = sqlite3PExpr(pParse, TK_DOT,
-                     sqlite3ExprAlloc(db, TK_ID, &t_old, 0),
-                     sqlite3ExprAlloc(db, TK_ID, &t_to_col,
-                              0));
-            r = sqlite3PExpr(pParse, TK_DOT,
-                     sqlite3ExprAlloc(db, TK_ID, &t_new, 0),
-                     sqlite3ExprAlloc(db, TK_ID, &t_to_col,
-                              0));
-            eq = sqlite3PExpr(pParse, TK_EQ, l, r);
-            when = sqlite3ExprAnd(db, when, eq);
+            struct Expr *old_val = sqlite3PExpr(pParse, TK_DOT,
+                sqlite3ExprAlloc(db, TK_ID, &t_old, 0),
+                sqlite3ExprAlloc(db, TK_ID, &t_to_col, 0));
+            struct Expr *new_val = sqlite3PExpr(pParse, TK_DOT,
+                sqlite3ExprAlloc(db, TK_ID, &t_new, 0),
+                sqlite3ExprAlloc(db, TK_ID, &t_to_col, 0));
+            struct Expr *old_is_null = sqlite3PExpr(
+                pParse, TK_ISNULL,
+                sqlite3ExprDup(db, old_val, 0), NULL);
+            eq = sqlite3PExpr(pParse, TK_EQ, old_val,
+                sqlite3ExprDup(db, new_val, 0));
+            struct Expr *new_non_null =
+                sqlite3PExpr(pParse, TK_NOTNULL, new_val, NULL);
+            struct Expr *non_null_eq =
+                sqlite3PExpr(pParse, TK_AND, new_non_null, eq);
+            struct Expr *no_action_needed =
+                sqlite3PExpr(pParse, TK_OR, old_is_null,
+                         non_null_eq);
+            when = sqlite3ExprAnd(db, when, no_action_needed);
          }

          if (action != FKEY_ACTION_RESTRICT &&
diff --git a/test/sql-tap/fkey1.test.lua b/test/sql-tap/fkey1.test.lua
index 3c29b097d..b419e4d59 100755
--- a/test/sql-tap/fkey1.test.lua
+++ b/test/sql-tap/fkey1.test.lua
@@ -1,6 +1,6 @@
  #!/usr/bin/env tarantool
  test = require("sqltester")
-test:plan(18)
+test:plan(25)

  -- This file implements regression tests for foreign keys.

@@ -233,4 +233,27 @@ test:do_execsql_test(
          -- </fkey1-6.3>
      })

+-- gh-3645: update col=Null do not activates ON UPDATE trigger.
+
+test:do_select_tests(
+    "fkey1-7",
+    {
+        {"0",
+            [[
+                CREATE TABLE T12 (A INTEGER PRIMARY KEY,
+                    B CHAR(5) UNIQUE);
+                CREATE TABLE T13 (A INTEGER PRIMARY KEY,
+                    B CHAR(5) UNIQUE,
+                    FOREIGN KEY (B) REFERENCES T12 (B) ON UPDATE SET NULL);
+                INSERT INTO T12 VALUES (1,'a');
+                INSERT INTO T13 VALUES (1,'a');
+            ]], {}},
+        {"1", "UPDATE T12 SET B = NULL", {}},
+        {"2", "SELECT * FROM T12", {1, ""}},
+        {"3", "SELECT * FROM T13", {1, ""}},
+        {"4", "UPDATE T12 SET B = 'a'", {}},
+        {"5", "SELECT * FROM T12", {1, "a"}},
+        {"6", "SELECT * FROM T13", {1, ""}},
+    })
+
  test:finish_test()

  reply	other threads:[~2018-10-11 13:20 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09 12:37 [tarantool-patches] " AKhatskevich
2018-10-09 19:14 ` [tarantool-patches] " n.pettik
2018-10-11 13:20   ` Alex Khatskevich [this message]
2018-10-17 15:41     ` n.pettik
2018-10-26  5:47 ` Kirill Yukhin

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