[tarantool-patches] Re: [PATCH 3/3] sql: fix passing FP values to integer iterator
n.pettik
korablev at tarantool.org
Thu Jun 6 16:51:26 MSK 2019
>> @@ -1128,8 +1129,9 @@ sqlWhereCodeOneLoopStart(WhereInfo * pWInfo, /* Complete information about the W
>> }
>> }
>> /* Inequality constraint comes always at the end of list. */
>> - if (pRangeStart != NULL &&
>> - idx_def->key_def->parts[nEq].type == FIELD_TYPE_INTEGER)
>> + enum field_type ineq_type = idx_def->key_def->parts[nEq].type;
>> + if (pRangeStart != NULL && (ineq_type == FIELD_TYPE_INTEGER ||
>> + ineq_type == FIELD_TYPE_UNSIGNED))
>
> 1. Please, add a test for unsigned. I thought that it is quite obvious -
> everything needs a test, especially if the bug was found during a review.
Surely, forgot about that:
diff --git a/test/sql/types.result b/test/sql/types.result
index bba39e320..383f93c1a 100644
--- a/test/sql/types.result
+++ b/test/sql/types.result
@@ -1012,3 +1012,35 @@ box.execute("SELECT a FROM t1 WHERE a IS NULL AND b IS NULL;")
box.space.T1:drop()
---
...
+format = {}
+---
+...
+format[1] = { name = 'ID', type = 'unsigned' }
+---
+...
+format[2] = { name = 'A', type = 'unsigned' }
+---
+...
+s = box.schema.create_space('T1', { format = format })
+---
+...
+_ = s:create_index('pk')
+---
+...
+_ = s:create_index('sk', { parts = { 'A' } })
+---
+...
+s:insert({ 1, 1 })
+---
+- [1, 1]
+...
+box.execute("SELECT a FROM t1 WHERE a IN (1.1, 2.1);")
+---
+- metadata:
+ - name: A
+ type: unsigned
+ rows: []
+...
+s:drop()
+---
+...
diff --git a/test/sql/types.test.lua b/test/sql/types.test.lua
index 16448436d..0218c5498 100644
--- a/test/sql/types.test.lua
+++ b/test/sql/types.test.lua
@@ -247,3 +247,14 @@ box.execute("SELECT a FROM t1 WHERE a = 1.5 AND b IS NULL;")
box.execute("SELECT a FROM t1 WHERE a IS NULL AND b IS NULL;")
box.space.T1:drop()
+
+format = {}
+format[1] = { name = 'ID', type = 'unsigned' }
+format[2] = { name = 'A', type = 'unsigned' }
+s = box.schema.create_space('T1', { format = format })
+_ = s:create_index('pk')
+_ = s:create_index('sk', { parts = { 'A' } })
+s:insert({ 1, 1 })
+box.execute("SELECT a FROM t1 WHERE a IN (1.1, 2.1);")
+
+s:drop()
>>>> diff --git a/src/box/sql/wherecode.c b/src/box/sql/wherecode.c
>>>> index 977c0fced..e779729c7 100644
>>>> --- a/src/box/sql/wherecode.c
>>>> +++ b/src/box/sql/wherecode.c
>>>> @@ -1086,31 +1086,61 @@ sqlWhereCodeOneLoopStart(WhereInfo * pWInfo, /* Complete information about the W
>>>> start_constraints = 1;
>>>> }
>>>> struct index_def *idx_pk = space->index[0]->def;
>>>> - int fieldno = idx_pk->key_def->parts[0].fieldno;
>>>> -
>>>> uint32_t pk_part_count = idx_pk->key_def->part_count;
>>>> - if (pk_part_count == 1 &&
>>>> - space->def->fields[fieldno].type == FIELD_TYPE_INTEGER) {
>>>> - /* Right now INTEGER PRIMARY KEY is the only option to
>>>> - * get Tarantool's INTEGER column type. Need special handling
>>>> - * here: try to loosely convert FLOAT to INT. If RHS type
>>>> - * is not INT or FLOAT - skip this ites, i.e. goto addrNxt.
>>>> - */
>>>> - int limit = pRangeStart == NULL ? nEq : nEq + 1;
>>>> - for (int i = 0; i < limit; i++) {
>>>> - if (idx_def->key_def->parts[i].fieldno ==
>>>> - idx_pk->key_def->parts[0].fieldno) {
>>>> - /* Here: we know for sure that table has INTEGER
>>>> - PRIMARY KEY, single column, and Index we're
>>>> - trying to use for scan contains this column. */
>>>> - if (i < nEq)
>>>> - sqlVdbeAddOp2(v, OP_MustBeInt, regBase + i, addrNxt);
>>>> - else
>>>> - force_integer_reg = regBase + i;
>>>> - break;
>>>> - }
>>>> + /*
>>>> + * Tarantool's iterator over integer fields doesn't
>>>> + * tolerate floating point values. Hence, if term
>>>> + * is equality comparison and value of operand is
>>>> + * not integer, we can skip it since it always
>>>> + * results in false: INT a == 0.5 -> false;
>>>> + * It is done using OP_MustBeInt facilities.
>>>> + * In case term is greater comparison (a > ?), we
>>>> + * should notify OP_SeekGT to process truncation of
>>>> + * floating point value: a > 0.5 -> a >= 1;
>>>> + * It is done by setting P5 flag for OP_Seek*.
>>>> + * It is worth mentioning that we do not need
>>>> + * this step when it comes for less comparison:
>>>> + * key is NULL in this case: values are ordered
>>>> + * as NULL, ... NULL, min_value, ..., so to
>>>> + * fetch min value we pass NULL to GT iterator.
>>>
>>> 4. I did not get the 'less comparator == compare with NULL'
>>> idea. Firstly you describe how to compare 'a > ?', this is
>>> fully understandable. Then you, as I see, go to the 'a < ?'
>>> case, but somewhy say, that it is the same as 'NULL < ?'.
>>> Do not understand.
>>
>> I say that in this case key which is passed to iterator is NULL
>> and type of iterator is GE.
>
> 2. Why? I still do not understand. What if I wrote 'a < 100'? you
> do not replace 100 with NULL. But the comment says, that for any
> 'less' operator a key is NULL: "when it comes for less comparison
> key is NULL”.
Consider example:
box.execute("CREATE TABLE t1(id INT PRIMARY KEY, a INT UNIQUE);")
box.execute("INSERT INTO t1 VALUES (1, 1), (2, 2), (3, -1), (4, NULL), (5, NULL);”)
box.execute("SELECT a FROM t1 WHERE a < 100;”)
Bytecode for this query is:
102> 0 Init 0 1 0 00 Start at 1
102> 1 IteratorOpen 1 1 0 space<name=T1> 00 index id = 1, space ptr = space<name=T1> or reg[0]; unique_unnamed_T1_2
102> 2 Explain 0 0 0 SEARCH TABLE T1 USING COVERING INDEX unique_unnamed_T1_2 (A<?) 00
102> 3 Null 0 1 0 00 r[1]=NULL
102> 4 SeekGT 1 10 1 1 00 key=r[1]
102> 5 Integer 100 1 0 00 r[1]=100
102> 6 IdxGE 1 10 1 1 00 key=r[1]
102> 7 Column 1 1 2 00 r[2]=T1.A
102> 8 ResultRow 2 1 0 00 output=r[2]
102> 9 Next 1 6 0 00
102> 10 Halt 0 0 0 00
As you can see, SeekGT accepts NULL as a key for iterator.
Then we iterate until search condition is true. So, basically
100 is replaced with NULL and not used as a key of iterator.
I wanted to underline this fact in my comment.
>> Consequently, pRangeStart is NULL.
>> I’ve slightly updated this part of comment:
>>
>> diff --git a/src/box/sql/wherecode.c b/src/box/sql/wherecode.c
>> index 3025e5e6b..01ee9ce90 100644
>> --- a/src/box/sql/wherecode.c
>> +++ b/src/box/sql/wherecode.c
>> @@ -1089,10 +1089,10 @@ sqlWhereCodeOneLoopStart(WhereInfo * pWInfo, /* Complete information about the W
>> * floating point value: a > 0.5 -> a >= 1;
>> * It is done by setting P5 flag for OP_Seek*.
>> * It is worth mentioning that we do not need
>> - * this step when it comes for less comparison:
>> - * key is NULL in this case: values are ordered
>> - * as NULL, ... NULL, min_value, ..., so to
>> - * fetch min value we pass NULL to GT iterator.
>> + * this step when it comes for less (<) comparison
>> + * of nullable field. Key is NULL in this case:
>> + * values are ordered as NULL, ... NULL, min_value,
>> + * so to fetch min value we pass NULL to GT iterator.
>>
>>
>> @@ -1112,24 +1112,33 @@ sqlWhereCodeOneLoopStart(WhereInfo * pWInfo, /* Complete information about the W
>> /*
>> * OP_MustBeInt consider NULLs as
>> * non-integer values, so firstly
>> * check whether value is NULL or not.
>> */
>> - seek_addr = sqlVdbeAddOp1(v, OP_IsNull,
>> + seek_addrs[i] = sqlVdbeAddOp1(v, OP_IsNull,
>> regBase);
>
> 3. Now the indentation is broken.
diff --git a/src/box/sql/wherecode.c b/src/box/sql/wherecode.c
index fde2efee0..4bd14bd5f 100644
--- a/src/box/sql/wherecode.c
+++ b/src/box/sql/wherecode.c
@@ -1130,7 +1130,7 @@ sqlWhereCodeOneLoopStart(WhereInfo * pWInfo, /* Complete information about the W
* check whether value is NULL or not.
*/
seek_addrs[i] = sqlVdbeAddOp1(v, OP_IsNull,
- regBase);
+ regBase);
sqlVdbeAddOp2(v, OP_MustBeInt, regBase + i,
addrNxt);
start_types[i] = FIELD_TYPE_SCALAR;
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