Re: [Tarantool-patches] [PATCH v1 1/1] sql: remove OP_Realify

[Mergen Imeev via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi! Thank you for the review!

On Fri, Jul 30, 2021 at 10:14:36AM +0300, Timur Safin wrote:
> Sorry. But this is part of a changes, which we have not agreed upon (reminder, that the 
> last agreement with PMs was to get rid of scalar, but keep number arithmetic), and which 
> [I believe] we would have to revert eventually. Please ask Kirill for ack, if he believes
> that we have to do it for "consistent types" task.
> 
> Let me clarify how I see this - in this particular case forcing real type semantics for 
> NUMBER field was pretty much consistent behavior. And using integer division on some 
> rows, but double on others is actually making things _much less_ consistent. 
> 
> Regards,
> 
Ok, no problem.

> 
> : From: imeevma@tarantool.org <imeevma@tarantool.org>
> : Subject: [PATCH v1 1/1] sql: remove OP_Realify
> : 
> : This opcode was used to convert INTEGER values to REAL. It is not
> : necessary in Tarantool and causes errors.
> : 
> : Due to OP_Realify two type of errors appeared:
> : 1) In some cases in trigger INTEGER may be converted to DOUBLE.
> : For example:
> : box.execute("CREATE TABLE t (i NUMBER PRIMARY KEY, n NUMBER);")
> : box.execute("CREATE TRIGGER t AFTER INSERT ON t FOR EACH ROW BEGIN UPDATE t
> : SET n = new.n; END;")
> : box.execute("INSERT INTO t VALUES (1, 1);")
> : box.execute("SELECT i / 2, n / 2 FROM t;")
> : 
> : Result:
> : tarantool> box.execute("SELECT i / 2, n / 2 FROM t;")
> : ---
> : - metadata:
> :   - name: COLUMN_1
> :     type: number
> :   - name: COLUMN_2
> :     type: number
> :   rows:
> :   - [0, 0.5]
> : ...
> : 
> : 2) If SELECT uses GROUP BY then it may return DOUBLE instead of INTEGER.
> : For example:
> : box.execute("CREATE TABLE t (i NUMBER PRIMARY KEY, n NUMBER);")
> : box.execute("INSERT INTO t VALUES (1,1);")
> : box.execute("SELECT i / 2, n / 2 FROM t GROUP BY n;")
> : 
> : Result:
> : tarantool> box.execute("SELECT i / 2, n / 2 FROM t GROUP BY n;")
> : ---
> : - metadata:
> :   - name: COLUMN_1
> :     type: number
> :   - name: COLUMN_2
> :     type: number
> :   rows:
> :   - [0.5, 0.5]
> : ...
> : 
> : This patch removes OP_Realify, after which these errors disappear.
> : 
> : Closes #5335
> : ---
> : https://github.com/tarantool/tarantool/issues/5335
> : https://github.com/tarantool/tarantool/tree/imeevma/gh-5335-remove-op-
> : realify
> : 
> :  ...gh-5335-remove-wrong-double-to-int-cast.md |  4 ++
> :  src/box/sql/expr.c                            | 13 -------
> :  src/box/sql/vdbe.c                            | 17 --------
> :  .../gh-5335-wrong-int-to-double-cast.test.lua | 39 +++++++++++++++++++
> :  4 files changed, 43 insertions(+), 30 deletions(-)
> :  create mode 100644 changelogs/unreleased/gh-5335-remove-wrong-double-to-
> : int-cast.md
> :  create mode 100755 test/sql-tap/gh-5335-wrong-int-to-double-cast.test.lua
> : 
> : diff --git a/changelogs/unreleased/gh-5335-remove-wrong-double-to-int-
> : cast.md b/changelogs/unreleased/gh-5335-remove-wrong-double-to-int-cast.md
> : new file mode 100644
> : index 000000000..b06805a7f
> : --- /dev/null
> : +++ b/changelogs/unreleased/gh-5335-remove-wrong-double-to-int-cast.md
> : @@ -0,0 +1,4 @@
> : +## bugfix/sql
> : +
> : +* Removed spontaneous conversion from INTEGER to DOUBLE in a field of type
> : +  NUMBER (gh-5335).
> : diff --git a/src/box/sql/expr.c b/src/box/sql/expr.c
> : index 3772596d6..d2624516c 100644
> : --- a/src/box/sql/expr.c
> : +++ b/src/box/sql/expr.c
> : @@ -3700,11 +3700,6 @@ sqlExprCodeTarget(Parse * pParse, Expr * pExpr, int
> : target)
> :  				sqlVdbeAddOp3(v, OP_Column,
> :  						  pAggInfo->sortingIdxPTab,
> :  						  pCol->iSorterColumn, target);
> : -				if (pCol->space_def->fields[pExpr->iAgg].type ==
> : -				    FIELD_TYPE_NUMBER) {
> : -					sqlVdbeAddOp1(v, OP_Realify,
> : -							  target);
> : -				}
> :  				return target;
> :  			}
> :  			/*
> : @@ -4260,14 +4255,6 @@ sqlExprCodeTarget(Parse * pParse, Expr * pExpr, int
> : target)
> :  				    (pExpr->iTable ? "new" : "old"),
> :  				    pExpr->space_def->fields[
> :  					pExpr->iColumn].name, target));
> : -
> : -			/* If the column has type NUMBER, it may currently be
> : stored as an
> : -			 * integer. Use OP_Realify to make sure it is really real.
> : -			 */
> : -			if (pExpr->iColumn >= 0 && def->fields[
> : -				pExpr->iColumn].type == FIELD_TYPE_NUMBER) {
> : -				sqlVdbeAddOp1(v, OP_Realify, target);
> : -			}
> :  			break;
> :  		}
> : 
> : diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
> : index 9e763ed85..0a3c904b1 100644
> : --- a/src/box/sql/vdbe.c
> : +++ b/src/box/sql/vdbe.c
> : @@ -1445,23 +1445,6 @@ case OP_MustBeInt: {            /* jump, in1 */
> :  	break;
> :  }
> : 
> : -/* Opcode: Realify P1 * * * *
> : - *
> : - * If register P1 holds an integer convert it to a real value.
> : - *
> : - * This opcode is used when extracting information from a column that
> : - * has float type.  Such column values may still be stored as
> : - * integers, for space efficiency, but after extraction we want them
> : - * to have only a real value.
> : - */
> : -case OP_Realify: {                  /* in1 */
> : -	pIn1 = &aMem[pOp->p1];
> : -	if (mem_is_int(pIn1)) {
> : -		mem_to_double(pIn1);
> : -	}
> : -	break;
> : -}
> : -
> :  /* Opcode: Cast P1 P2 * * *
> :   * Synopsis: type(r[P1])
> :   *
> : diff --git a/test/sql-tap/gh-5335-wrong-int-to-double-cast.test.lua
> : b/test/sql-tap/gh-5335-wrong-int-to-double-cast.test.lua
> : new file mode 100755
> : index 000000000..d29324a28
> : --- /dev/null
> : +++ b/test/sql-tap/gh-5335-wrong-int-to-double-cast.test.lua
> : @@ -0,0 +1,39 @@
> : +#!/usr/bin/env tarantool
> : +local test = require("sqltester")
> : +test:plan(2)
> : +
> : +test:execsql([[
> : +    CREATE TABLE t1 (i NUMBER PRIMARY KEY, n NUMBER);
> : +    CREATE TABLE t2 (i NUMBER PRIMARY KEY, n NUMBER);
> : +    CREATE TRIGGER r AFTER INSERT ON t1 FOR EACH ROW BEGIN UPDATE t1 SET n
> : = new.n; END;
> : +    INSERT INTO t1 VALUES (1, 1);
> : +    INSERT INTO t2 VALUES (1, 1);
> : +]])
> : +
> : +--
> : +-- Make sure that there are no unnecesary INTEGER to DOUBLE implicit cast
> : in
> : +-- field of type NUMBER.
> : +--
> : +test:do_execsql_test(
> : +    "gh-5335-1",
> : +    [[
> : +        SELECT i / 2, n / 2 FROM t1;
> : +    ]], {
> : +        0, 0
> : +    })
> : +
> : +test:do_execsql_test(
> : +    "gh-5335-2",
> : +    [[
> : +        SELECT i / 2, n / 2 FROM t2 GROUP BY n;
> : +    ]], {
> : +        0, 0
> : +    })
> : +
> : +test:execsql([[
> : +    DROP TRIGGER r;
> : +    DROP TABLE t1;
> : +    DROP TABLE t2;
> : +]])
> : +
> : +test:finish_test()
> : --
> : 2.25.1
> 
>