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! My answers, diff and new patch below.

On Mon, Jul 26, 2021 at 10:58:05PM +0200, Vladislav Shpilevoy wrote:
> Thanks for the patch!
> 
> See 2 comments below.
> 
> >  src/box/sql/expr.c                            | 13 -------
> >  src/box/sql/vdbe.c                            | 17 --------
> >  .../gh-5335-wrong-int-to-double-cast.test.lua | 39 +++++++++++++++++++
> 
> 1. Please, add a changelog file.
> 
Added.

> > 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..efcae911c
> > --- /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 implicit cast from string to integer works correctly in
> > +-- arithmetic operations.
> 
> 2. From string to integer? Where are the strings?
> 
Fixed. Most likely I forgot to change this comment after I copied tests to use
as a template.

> > +--
> > +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()
> > 

Diff:

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/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
index efcae911c..d29324a28 100755
--- 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
@@ -11,8 +11,8 @@ test:execsql([[
 ]])
 
 --
--- Make sure that implicit cast from string to integer works correctly in
--- arithmetic operations.
+-- Make sure that there are no unnecesary INTEGER to DOUBLE implicit cast in
+-- field of type NUMBER.
 --
 test:do_execsql_test(
     "gh-5335-1",



Patch:


commit f15e1aefdd7cafd380e66f7b5acdafb7ae5bdca6
Author: Mergen Imeev <imeevma@gmail.com>
Date:   Sat Sep 26 12:43:18 2020 +0300

    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

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()