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

[Timur Safin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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,


: 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