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infoschema: don't load table info to get auto_increment value #57296

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merged 5 commits into from
Nov 13, 2024
Merged

infoschema: don't load table info to get auto_increment value #57296

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46cb7bb
infoschema: don't load table info to get auto_increment value
tangenta Nov 11, 2024
ef06307
update bazel
tangenta Nov 11, 2024
fbe0fd2
optimize GetDataAndIndexLength
CbcWestwolf Nov 11, 2024
671d89f
fix TestInfoSchemaFieldValue
tangenta Nov 12, 2024
bc5e3d1
address comment
tangenta Nov 13, 2024
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20 changes: 19 additions & 1 deletion pkg/executor/infoschema_reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -242,11 +242,29 @@ func getAutoIncrementID(
sctx sessionctx.Context,
tblInfo *model.TableInfo,
) int64 {
if raw, ok := is.(*infoschema.SessionExtendedInfoSchema); ok {
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Why do we need this type assertion?

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Infoschema that we can get from session is wrapped with SessionExtendedInfoSchema:

tidb/pkg/table/temptable/infoschema.go

Line 23 in a5832b4

func AttachLocalTemporaryTableInfoSchema(sctx variable.SessionVarsProvider, is infoschema.InfoSchema) infoschema.InfoSchema {

v2, ok := raw.InfoSchema.(interface {
TableIsCached(id int64) bool
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Could we use IsV2 which seems easier to understand? It seems that the v1 tables are all cached.

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bc5e3d1

})
if ok {
isCached := v2.TableIsCached(tblInfo.ID)
if !isCached {
// Loading table info from kv storage invalidates the cached auto_increment id.
return 0
}
}
}
tbl, ok := is.TableByID(context.Background(), tblInfo.ID)
if !ok {
return 0
}
return tbl.Allocators(sctx.GetTableCtx()).Get(autoid.AutoIncrementType).Base() + 1
alloc := tbl.Allocators(sctx.GetTableCtx()).Get(autoid.AutoIncrementType)
if alloc == nil || alloc.Base() == 0 {
// It may not be loaded yet.
// To show global next autoID, one should use `show table x next_row_id`.
return 0
}
return alloc.Base() + 1
}

func hasPriv(ctx sessionctx.Context, priv mysql.PrivilegeType) bool {
Expand Down
25 changes: 25 additions & 0 deletions pkg/infoschema/infoschema_v2.go
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Expand Up @@ -691,6 +691,31 @@ func (is *infoschemaV2) IterateAllTableItems(visit func(TableItem) bool) {
})
}

// TableIsCached checks whether the table is cached.
func (is *infoschemaV2) TableIsCached(id int64) (ok bool) {
if !tableIDIsValid(id) {
return false
}

itm, ok := is.searchTableItemByID(id)
if !ok {
return false
}

if isTableVirtual(id) {
if raw, exist := is.Data.specials.Load(itm.dbName.L); exist {
schTbls := raw.(*schemaTables)
_, ok = schTbls.tables[itm.tableName.L]
return ok
}
return false
}

key := tableCacheKey{itm.tableID, itm.schemaVersion}
tbl, found := is.tableCache.Get(key)
return found && tbl != nil
}

// IsSpecialDB tells whether the database is a special database.
func IsSpecialDB(dbName string) bool {
return dbName == util.InformationSchemaName.L ||
Expand Down
3 changes: 2 additions & 1 deletion pkg/infoschema/test/infoschemav2test/BUILD.bazel
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Expand Up @@ -8,12 +8,13 @@ go_test(
"v2_test.go",
],
flaky = True,
shard_count = 11,
shard_count = 12,
deps = [
"//pkg/domain",
"//pkg/domain/infosync",
"//pkg/infoschema",
"//pkg/infoschema/context",
"//pkg/meta/autoid",
"//pkg/parser/auth",
"//pkg/parser/model",
"//pkg/sessionctx/variable",
Expand Down
24 changes: 24 additions & 0 deletions pkg/infoschema/test/infoschemav2test/v2_test.go
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Expand Up @@ -28,6 +28,7 @@ import (
"github.com/pingcap/tidb/pkg/domain/infosync"
"github.com/pingcap/tidb/pkg/infoschema"
infoschemacontext "github.com/pingcap/tidb/pkg/infoschema/context"
"github.com/pingcap/tidb/pkg/meta/autoid"
"github.com/pingcap/tidb/pkg/parser/auth"
"github.com/pingcap/tidb/pkg/parser/model"
"github.com/pingcap/tidb/pkg/sessionctx/variable"
Expand Down Expand Up @@ -534,3 +535,26 @@ func TestSnapshotInfoschemaReader(t *testing.T) {
sql = fmt.Sprintf("select * from INFORMATION_SCHEMA.TABLES as of timestamp '%s' where table_schema = 'issue55827'", timeStr)
tk.MustQuery(sql).Check(testkit.Rows())
}

func TestInfoSchemaCachedAutoIncrement(t *testing.T) {
store := testkit.CreateMockStore(t)
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test")
autoid.SetStep(1)
tk.MustExec("set @@global.tidb_schema_cache_size = 0;")
tk.MustExec("create table t (a int primary key auto_increment);")
autoIncQuery := "select auto_increment from information_schema.tables where table_name = 't' and table_schema = 'test';"

tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
tk.MustExec("insert into t values (),(),();")
tk.MustQuery(autoIncQuery).Check(testkit.Rows("4"))

tk.MustExec("set @@global.tidb_schema_cache_size = 1024 * 1024 * 1024;")
tk.MustExec("create table t1 (a int);") // trigger infoschema cache reload
tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
tk.MustExec("insert into t values ();")
tk.MustQuery(autoIncQuery).Check(testkit.Rows("5"))
tk.MustExec("set @@global.tidb_schema_cache_size = 0;")
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There is an API you can use to evict table cache directly, although trigger reload can get the same effect.

	is := dom.InfoSchema()
	ok, v2 := infoschema.IsV2(is)
	require.True(t, ok)
	v2.EvictTable(model.NewCIStr("test"), model.NewCIStr("t1"))

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The schema is not v2 if we don't reload.

tk.MustExec("drop table t1;") // trigger infoschema cache reload
tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
}