[tarantool-patches] Re: [PATCH] sql: fix fk set null clause
n.pettik
korablev at tarantool.org
Tue Oct 9 22:14:37 MSK 2018
> After changing behavior of the `IS` operator (#b3a3ddb571),
> `SET NULL` was rewritten to use `EQ` instead. Which do not respect
Nit: doesn’t.
> 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?
>
> 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.
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);
> }
>
> 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.
> @@ -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.
> + INSERT INTO T1 VALUES (1,'a');
> + INSERT INTO T2 VALUES (1,'a’);
Nit: indentation is broken.
> + ]], {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).
> +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’?
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