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*: fix bug that UnionScan can't keep order caused wrong result #33218

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merged 10 commits into from
Mar 22, 2022
Merged

*: fix bug that UnionScan can't keep order caused wrong result #33218

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24993b0
*: fix bug that UnionScan can't keep order caused wrong result
tiancaiamao Mar 17, 2022
64fef56
address comment
tiancaiamao Mar 21, 2022
5e78b50
make fmt
tiancaiamao Mar 21, 2022
d09fd16
Merge branch 'master' into issue-33175
tiancaiamao Mar 21, 2022
09ebb14
address comment
tiancaiamao Mar 22, 2022
dac6e4d
clean debug code
tiancaiamao Mar 22, 2022
556bc7f
clean up code
tiancaiamao Mar 22, 2022
b3678e5
Update executor/mem_reader.go
tiancaiamao Mar 22, 2022
41b3f5b
Merge branch 'master' into issue-33175
tiancaiamao Mar 22, 2022
5d5555e
Merge branch 'master' into issue-33175
ti-chi-bot Mar 22, 2022
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29 changes: 29 additions & 0 deletions executor/mem_reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,14 @@ func (m *memIndexReader) getMemRows(ctx context.Context) ([][]types.Datum, error
}

mutableRow := chunk.MutRowFromTypes(m.retFieldTypes)

// TODO: `IterReverse` is not used... to get the same effect, reverse the kv ranges first,
// Then reverse the whole added rows.
// [99, 100] [44, 45] [1, 3] => [1, 3] [44, 45] [99, 100] => [100, 99] [45, 44] [3 1]
if m.desc {
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@lcwangchao lcwangchao Mar 21, 2022 •
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It may still cause bugs when the int is signed, try the following:

create global temporary table `tmp2` (id bigint primary key) on commit delete rows;
begin;
insert into tmp2 values(-2),(-1),(0),(1),(2);
-- The following  query will give a wrong result: 
-- expected 2, 1, 0, -1, -2 , actual: -1, -2, 2, 1
select * from tmp2 where id <= -1 or id > 0 order by id desc;

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Update, PTAL @lcwangchao

reverseKVRanges(m.kvRanges)
}

err := iterTxnMemBuffer(m.ctx, m.cacheTable, m.kvRanges, func(key, value []byte) error {
data, err := m.decodeIndexKeyValue(key, value, tps)
if err != nil {
Expand Down Expand Up @@ -239,6 +247,13 @@ func (m *memTableReader) getMemRows(ctx context.Context) ([][]types.Datum, error
defer span1.Finish()
opentracing.ContextWithSpan(ctx, span1)
}

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// TODO: `IterReverse` is not used... to get the same effect, reverse the kv ranges first,
// Then reverse the whole added rows.
if m.desc {
reverseKVRanges(m.kvRanges)
}

mutableRow := chunk.MutRowFromTypes(m.retFieldTypes)
err := iterTxnMemBuffer(m.ctx, m.cacheTable, m.kvRanges, func(key, value []byte) error {
row, err := m.decodeRecordKeyValue(key, value)
Expand Down Expand Up @@ -407,6 +422,7 @@ func iterTxnMemBuffer(ctx sessionctx.Context, cacheTable kv.MemBuffer, kvRanges
if len(iter.Value()) == 0 {
continue
}

err = fn(iter.Key(), iter.Value())
if err != nil {
return err
Expand Down Expand Up @@ -435,6 +451,12 @@ func getSnapIter(ctx sessionctx.Context, cacheTable kv.MemBuffer, rg kv.KeyRange
return snapCacheIter, nil
}

func reverseKVRanges(rows []kv.KeyRange) {
for i, j := 0, len(rows)-1; i < j; i, j = i+1, j-1 {
rows[i], rows[j] = rows[j], rows[i]
}
}

func reverseDatumSlice(rows [][]types.Datum) {
for i, j := 0, len(rows)-1; i < j; i, j = i+1, j-1 {
rows[i], rows[j] = rows[j], rows[i]
Expand Down Expand Up @@ -540,6 +562,13 @@ func (m *memIndexLookUpReader) getMemRows(ctx context.Context) ([][]types.Datum,
numHandles := 0
for i, tbl := range tbls {
m.idxReader.kvRanges = kvRanges[i]
// TODO: `IterReverse` is not used... to get the same effect, reverse the kv ranges first,
// Then reverse the whole added rows.
// [99, 100] [44, 45] [1, 3] => [1, 3] [44, 45] [99, 100] => [100, 99] [45, 44] [3 1]
if m.desc {
reverseKVRanges(m.idxReader.kvRanges)
}

handles, err := m.idxReader.getMemRowsHandle()
if err != nil {
return nil, err
Expand Down
12 changes: 3 additions & 9 deletions planner/core/handle_cols.go
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Expand Up @@ -239,15 +239,9 @@ func (ib *IntHandleCols) NumCols() int {

// Compare implements the kv.HandleCols interface.
func (ib *IntHandleCols) Compare(a, b []types.Datum, ctors []collate.Collator) (int, error) {
aInt := a[ib.col.Index].GetInt64()
bInt := b[ib.col.Index].GetInt64()
if aInt == bInt {
return 0, nil
}
if aInt < bInt {
return -1, nil
}
return 1, nil
aVal := &a[ib.col.Index]
bVal := &b[ib.col.Index]
return aVal.Compare(nil, bVal, ctors[ib.col.Index])
}

// GetFieldsTypes implements the kv.HandleCols interface.
Expand Down
72 changes: 72 additions & 0 deletions planner/core/integration_test.go
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Expand Up @@ -6243,3 +6243,75 @@ func TestTiFlashPartitionTableScan(t *testing.T) {
tk.MustExec("drop table rp_t;")
tk.MustExec("drop table hp_t;")
}

func TestIssue33175(t *testing.T) {
store, _, clean := testkit.CreateMockStoreAndDomain(t)
defer clean()
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test")
tk.MustExec("create table t (id bigint(45) unsigned not null, c varchar(20), primary key(id));")
tk.MustExec("insert into t values (9734095886065816707, 'a'), (10353107668348738101, 'b'), (0, 'c');")
tk.MustExec("begin")
tk.MustExec("insert into t values (33, 'd');")
tk.MustQuery("select max(id) from t;").Check(testkit.Rows("10353107668348738101"))
tk.MustExec("rollback")

tk.MustExec("alter table t cache")
for {
tk.MustQuery("select max(id) from t;").Check(testkit.Rows("10353107668348738101"))
if tk.Session().GetSessionVars().StmtCtx.ReadFromTableCache {
break
}
}

// // With subquery, like the original issue case.
for {
tk.MustQuery("select * from t where id > (select max(id) from t where t.id > 0);").Check(testkit.Rows())
if tk.Session().GetSessionVars().StmtCtx.ReadFromTableCache {
break
}
}

// Test order by desc / asc.
tk.MustQuery("select id from t order by id desc;").Check(testkit.Rows(
"10353107668348738101",
"9734095886065816707",
"0"))

tk.MustQuery("select id from t order by id asc;").Check(testkit.Rows(
"0",
"9734095886065816707",
"10353107668348738101"))

tk.MustExec("alter table t nocache")
tk.MustExec("drop table t")

// Cover more code that use union scan
// TableReader/IndexReader/IndexLookup
for idx, q := range []string{
"create temporary table t (id bigint unsigned, c int default null, index(id))",
"create temporary table t (id bigint unsigned primary key)",
} {
tk.MustExec(q)
tk.MustExec("insert into t(id) values (1), (3), (9734095886065816707), (9734095886065816708)")
tk.MustQuery("select min(id) from t").Check(testkit.Rows("1"))
tk.MustQuery("select max(id) from t").Check(testkit.Rows("9734095886065816708"))
tk.MustQuery("select id from t order by id asc").Check(testkit.Rows(
"1", "3", "9734095886065816707", "9734095886065816708"))
tk.MustQuery("select id from t order by id desc").Check(testkit.Rows(
"9734095886065816708", "9734095886065816707", "3", "1"))
if idx == 0 {
tk.MustQuery("select * from t order by id asc").Check(testkit.Rows(
"1 <nil>",
"3 <nil>",
"9734095886065816707 <nil>",
"9734095886065816708 <nil>"))
tk.MustQuery("select * from t order by id desc").Check(testkit.Rows(
"9734095886065816708 <nil>",
"9734095886065816707 <nil>",
"3 <nil>",
"1 <nil>"))
}
tk.MustExec("drop table t")
}
}