feat(core/translate): Implement SQLite min/max special-case for bare columns

[nunogoncalves03]

Description

This PR implements the correct handling of bare columns in GROUP BY queries that contain exactly one MIN or MAX aggregate, as described in #3444.

How does it work?

• Detects queries with exactly one MIN or MAX aggregate in the GROUP BY queries
• Tracks the current minimum or maximum value and updates bare columns only when a new minimum or maximum is found
• Ensures that bare columns are copied from the row that produces the minimum or maximum value, rather than arbitrarily from the group

NULL handling:

• When all values are NULL, bare columns are updated for each NULL row, so the last NULL row wins.
• When there are ties involving non-NULL values, bare columns are updated only when a value is strictly less than (for MIN) or greater than (for MAX) the current value. As a result, the first row that establishes the min/max wins.

Previous bytecode

turso> explain select a, b, max(c) from t group by a;
addr  opcode             p1    p2    p3    p4             p5  comment
----  -----------------  ----  ----  ----  -------------  --  -------
0     Init               0     47    0                    0   Start at 47
1     Null               0     10    0                    0   r[10]=NULL
2     SorterOpen         0     3     0     k(1,B)         0   cursor=0
3     Integer            0     6     0                    0   r[6]=0; clear group by abort flag
4     Null               0     7     0                    0   r[7]=NULL; initialize group by comparison registers to NULL
5     Gosub              15    43    0                    0   ; go to clear accumulator subroutine
6     OpenRead           2     2     0     k(4,B,B,B)     0   table=t, root=2, iDb=0
7     Rewind             2     14    0                    0   Rewind table t
8       Column           2     0     12                   0   r[12]=t.a
9       Column           2     1     13                   0   r[13]=t.b
10      Column           2     2     14                   0   r[14]=t.c
11      MakeRecord       12    3     11                   0   r[11]=mkrec(r[12..14])
12      SorterInsert     0     11    0     0              0   key=r[11]
13    Next               2     8     0                    0   
14    OpenPseudo         1     11    3                    0   3 columns in r[11]
15    SorterSort         0     31    0                    0   
16      SorterData       0     11    1                    0   r[11]=data
17      Column           1     0     16                   0   r[16]=pseudo.column 0
18      Compare          7     16    1     k(1, Binary)   0   r[7..7]==r[16..16]
19      Jump             20    24    20                   0   ; start new group if comparison is not equal
20      Gosub            4     35    0                    0   ; check if ended group had data, and output if so
21      Move             16    7     1                    0   r[7..7]=r[16..16]
22      IfPos            6     46    0                    0   r[6]>0 -> r[6]-=0, goto 46; check abort flag
23      Gosub            15    43    0                    0   ; goto clear accumulator subroutine
24      Column           1     2     17                   0   r[17]=pseudo.column 2
25      AggStep          0     17    10    max            0   accum=r[10] step(r[17])
26      If               5     29    0                    0   if r[5] goto 29; don't emit group columns if continuing existing group
27      Column           1     0     8                    0   r[8]=pseudo.column 0
28      Column           1     1     9                    0   r[9]=pseudo.column 1
29      Integer          1     5     0                    0   r[5]=1; indicate data in accumulator
30    SorterNext         0     16    0                    0   
31    Gosub              4     35    0                    0   ; emit row for final group
32    Goto               0     46    0                    0   ; group by finished
33    Integer            1     6     0                    0   r[6]=1
34    Return             4     0     0                    0   
35    IfPos              5     37    0                    0   r[5]>0 -> r[5]-=0, goto 37; output group by row subroutine start
36    Return             4     0     0                    0   
37    AggFinal           0     10    0     max            0   accum=r[10]
38    Copy               8     1     0                    0   r[1]=r[8]
39    Copy               9     2     0                    0   r[2]=r[9]
40    Copy               10    3     0                    0   r[3]=r[10]
41    ResultRow          1     3     0                    0   output=r[1..3]
42    Return             4     0     0                    0   
43    Null               0     8     10                   0   r[8..10]=NULL; clear accumulator subroutine start
44    Integer            0     5     0                    0   r[5]=0
45    Return             15    0     0                    0   
46    Halt               0     0     0                    0   
47    Transaction        0     1     1                    0   iDb=0 tx_mode=Read
48    Goto               0     1     0                    0   

New bytecode

turso> explain select a, b, max(c) from t group by a;
addr  opcode             p1    p2    p3    p4             p5  comment
----  -----------------  ----  ----  ----  -------------  --  -------
0     Init               0     66    0                    0   Start at 66
1     Null               0     12    0                    0   r[12]=NULL
2     SorterOpen         0     3     0     k(1,B)         0   cursor=0
3     Integer            0     6     0                    0   r[6]=0; clear group by abort flag
4     Null               0     7     0                    0   r[7]=NULL; initialize group by comparison registers to NULL
5     Gosub              17    60    0                    0   ; go to clear accumulator subroutine
6     OpenRead           2     2     0     k(4,B,B,B)     0   table=t, root=2, iDb=0
7     Rewind             2     14    0                    0   Rewind table t
8       Column           2     0     14                   0   r[14]=t.a
9       Column           2     1     15                   0   r[15]=t.b
10      Column           2     2     16                   0   r[16]=t.c
11      MakeRecord       14    3     13                   0   r[13]=mkrec(r[14..16])
12      SorterInsert     0     13    0     0              0   key=r[13]
13    Next               2     8     0                    0   
14    OpenPseudo         1     13    3                    0   3 columns in r[13]
15    SorterSort         0     48    0                    0   
16      SorterData       0     13    1                    0   r[13]=data
17      Column           1     0     18                   0   r[18]=pseudo.column 0
18      Compare          7     18    1     k(1, Binary)   0   r[7..7]==r[18..18]
19      Jump             20    24    20                   0   ; start new group if comparison is not equal
20      Gosub            4     52    0                    0   ; check if ended group had data, and output if so
21      Move             18    7     1                    0   r[7..7]=r[18..18]
22      IfPos            6     65    0                    0   r[6]>0 -> r[6]-=0, goto 65; check abort flag
23      Gosub            17    60    0                    0   ; goto clear accumulator subroutine
24      Column           1     2     19                   0   r[19]=pseudo.column 2
25      Integer          0     9     0                    0   r[9]=0
26      NotNull          19    31    0                    0   r[19]!=NULL -> goto 31
27      IsNull           8     29    0                    0   if (r[8]==NULL) goto 29
28      Goto             0     38    0                    0   
29      Integer          1     9     0                    0   r[9]=1
30      Goto             0     38    0                    0   
31      NotNull          8     34    0                    0   r[8]!=NULL -> goto 34
32      Integer          1     9     0                    0   r[9]=1
33      Goto             0     38    0                    0   
34      Copy             8     20    0                    0   r[20]=r[8]
35      Compare          19    20    1     k(1, Binary)   0   r[19..19]==r[20..20]
36      Jump             38    38    37                   0   
37      Integer          1     9     0                    0   r[9]=1
38      Column           1     2     21                   0   r[21]=pseudo.column 2
39      AggStep          0     21    12    max            0   accum=r[12] step(r[21])
40      IfPos            9     42    0                    0   r[9]>0 -> r[9]-=0, goto 42
41      Goto             0     46    0                    0   
42      Column           1     2     22                   0   r[22]=pseudo.column 2
43      Copy             22    8     0                    0   r[8]=r[22]
44      Column           1     0     10                   0   r[10]=pseudo.column 0
45      Column           1     1     11                   0   r[11]=pseudo.column 1
46      Integer          1     5     0                    0   r[5]=1; indicate data in accumulator
47    SorterNext         0     16    0                    0   
48    Gosub              4     52    0                    0   ; emit row for final group
49    Goto               0     65    0                    0   ; group by finished
50    Integer            1     6     0                    0   r[6]=1
51    Return             4     0     0                    0   
52    IfPos              5     54    0                    0   r[5]>0 -> r[5]-=0, goto 54; output group by row subroutine start
53    Return             4     0     0                    0   
54    AggFinal           0     12    0     max            0   accum=r[12]
55    Copy               10    1     0                    0   r[1]=r[10]
56    Copy               11    2     0                    0   r[2]=r[11]
57    Copy               12    3     0                    0   r[3]=r[12]
58    ResultRow          1     3     0                    0   output=r[1..3]
59    Return             4     0     0                    0   
60    Null               0     10    12                   0   r[10..12]=NULL; clear accumulator subroutine start
61    Null               0     8     0                    0   r[8]=NULL
62    Integer            0     9     0                    0   r[9]=0
63    Integer            0     5     0                    0   r[5]=0
64    Return             17    0     0                    0   
65    Halt               0     0     0                    0   
66    Transaction        0     1     1                    0   iDb=0 tx_mode=Read
67    Goto               0     1     0                    0 

Motivation and context

Fixes #3444.

Currently, Turso does not have this special-case handling for bare columns:

turso> create table t(a,b,c);
turso> insert into t values (1, 'a', 'a'), (1, 'b', 'b'), (1, 'c', 'c');
turso> select a, b, max(c) from t group by a; -- b column is incorrect
┌───┬───┬───────────┐
│ a │ b │ max (t.c) │
├───┼───┼───────────┤
│ 1 │ a │ c         │
└───┴───┴───────────┘
turso> select a, b, min(c) from t group by a; -- this one happens to be correct
┌───┬───┬───────────┐
│ a │ b │ min (t.c) │
├───┼───┼───────────┤
│ 1 │ a │ a         │
└───┴───┴───────────┘

SQLite does:

sqlite> create table t(a,b,c);
sqlite> insert into t values (1, 'a', 'a'), (1, 'b', 'b'), (1, 'c', 'c');
sqlite> select a, b, max(c) from t group by a;
1|c|c
sqlite> select a, b, min(c) from t group by a;
1|a|a

Description of AI Usage

Claude Sonnet 4.5 was heavily used in this PR. I relied on it to understand the existing group-by flow, from query planning through bytecode generation, and then used it iteratively to generate most of the code until I reached the desired solution. It was also used to create some of the test cases.

[turso-bot]

Please review @pereman2