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planner: fix tiflash path will be identified as table dual #49338

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merged 2 commits into from
Dec 12, 2023
Merged

planner: fix tiflash path will be identified as table dual #49338

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8df8aad
fix tiflash path will be identified as table dual
AilinKid Dec 11, 2023
730e233
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AilinKid Dec 11, 2023
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7 changes: 7 additions & 0 deletions pkg/planner/core/casetest/enforcempp/enforce_mpp_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@ func TestEnforceMPP(t *testing.T) {
tk.MustExec("create table t(a int, b int)")
tk.MustExec("create index idx on t(a)")
tk.MustExec("CREATE TABLE `s` (\n `a` int(11) DEFAULT NULL,\n `b` int(11) DEFAULT NULL,\n `c` int(11) DEFAULT NULL,\n `d` int(11) DEFAULT NULL,\n UNIQUE KEY `a` (`a`),\n KEY `ii` (`a`,`b`)\n)")
tk.MustExec("create table t3(id int, sala char(10), name char(100), primary key(id, sala)) partition by list columns (sala)(partition p1 values in('a'));")

// Default RPC encoding may cause statistics explain result differ and then the test unstable.
tk.MustExec("set @@tidb_enable_chunk_rpc = on")
Expand All @@ -65,6 +66,12 @@ func TestEnforceMPP(t *testing.T) {
Available: true,
}
}
if tblInfo.Name.L == "t3" {
tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
Count: 1,
Available: true,
}
}
}

var input []string
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4 changes: 3 additions & 1 deletion pkg/planner/core/casetest/enforcempp/testdata/enforce_mpp_suite_in.json
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Expand Up @@ -22,7 +22,9 @@
"explain format='verbose' select count(*) from t where a=1",
"explain format='verbose' select /*+ read_from_storage(tikv[t]) */ count(*) from t where a=1",
"explain format='verbose' select /*+ read_from_storage(tiflash[t]) */ count(*) from t where a=1",
"explain select /*+ READ_FROM_STORAGE(TIFLASH[s]) */ a from s where a = 10 and b is null; -- index path huristic rule will prune tiflash path"
"explain select /*+ READ_FROM_STORAGE(TIFLASH[s]) */ a from s where a = 10 and b is null; -- index path huristic rule will prune tiflash path",
"explain select /*+ read_from_storage(tiflash[t3]) */ * from t3 where sala='a' and id =1; -- once hinted, walk with tiflash range scan",
"explain select * from t3 where sala='a' and id =1; -- once not hinted, walk with tikv point get"
]
},
{
Expand Down
28 changes: 24 additions & 4 deletions pkg/planner/core/casetest/enforcempp/testdata/enforce_mpp_suite_out.json
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Expand Up @@ -177,13 +177,33 @@
{
"SQL": "explain select /*+ READ_FROM_STORAGE(TIFLASH[s]) */ a from s where a = 10 and b is null; -- index path huristic rule will prune tiflash path",
"Plan": [
"TableReader_12 0.10 root MppVersion: 2, data:ExchangeSender_11",
"└─ExchangeSender_11 0.10 mpp[tiflash] ExchangeType: PassThrough",
"TableReader_9 0.10 root MppVersion: 2, data:ExchangeSender_8",
"└─ExchangeSender_8 0.10 mpp[tiflash] ExchangeType: PassThrough",
" └─Projection_5 0.10 mpp[tiflash] test.s.a",
" └─Selection_10 0.10 mpp[tiflash] isnull(test.s.b)",
" └─TableFullScan_9 10.00 mpp[tiflash] table:s pushed down filter:eq(test.s.a, 10), keep order:false, stats:pseudo"
" └─Selection_7 0.10 mpp[tiflash] isnull(test.s.b)",
" └─TableFullScan_6 10.00 mpp[tiflash] table:s pushed down filter:eq(test.s.a, 10), keep order:false, stats:pseudo"
],
"Warn": null
},
{
"SQL": "explain select /*+ read_from_storage(tiflash[t3]) */ * from t3 where sala='a' and id =1; -- once hinted, walk with tiflash range scan",
"Plan": [
"TableReader_12 0.01 root MppVersion: 2, data:ExchangeSender_11",
"└─ExchangeSender_11 0.01 mpp[tiflash] ExchangeType: PassThrough",
" └─TableRangeScan_10 1.00 mpp[tiflash] table:t3, partition:p1 range:[1 \"a\",1 \"a\"], keep order:false, stats:pseudo"
],
"Warn": [
"disable dynamic pruning due to t3 has no global stats"
]
},
{
"SQL": "explain select * from t3 where sala='a' and id =1; -- once not hinted, walk with tikv point get",
"Plan": [
"Point_Get_6 1.00 root table:t3, partition:p1, clustered index:PRIMARY(id, sala) "
],
"Warn": [
"disable dynamic pruning due to t3 has no global stats"
]
}
]
},
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26 changes: 23 additions & 3 deletions pkg/planner/core/stats.go
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Original file line number Diff line number Diff line change
Expand Up @@ -307,6 +307,22 @@ func (ds *DataSource) derivePathStatsAndTryHeuristics() error {
selected, uniqueBest, refinedBest *util.AccessPath
isRefinedPath bool
)
// step1: if user prefer tiFlash store type, tiFlash path should always be built anyway ahead.
var tiflashPath *util.AccessPath
if ds.preferStoreType&preferTiFlash != 0 {
for _, path := range ds.possibleAccessPaths {
if path.StoreType == kv.TiFlash {
err := ds.deriveTablePathStats(path, ds.pushedDownConds, false)
if err != nil {
return err
}
path.IsSingleScan = true
tiflashPath = path
break
}
}
}
// step2: kv path should follow the heuristic rules.
for _, path := range ds.possibleAccessPaths {
if path.IsTablePath() {
err := ds.deriveTablePathStats(path, ds.pushedDownConds, false)
Expand All @@ -318,7 +334,9 @@ func (ds *DataSource) derivePathStatsAndTryHeuristics() error {
ds.deriveIndexPathStats(path, ds.pushedDownConds, false)
path.IsSingleScan = ds.isSingleScan(path.FullIdxCols, path.FullIdxColLens)
}
// step: 3
// Try some heuristic rules to select access path.
// tiFlash path also have table-range-scan (range point like here) to be heuristic treated.
if len(path.Ranges) == 0 {
selected = path
break
Expand Down Expand Up @@ -381,13 +399,15 @@ func (ds *DataSource) derivePathStatsAndTryHeuristics() error {
// heuristic rule pruning other path should consider hint prefer.
// If no hints and some path matches a heuristic rule, just remove other possible paths.
if selected != nil {
// if user wanna tiFlash read, while current heuristic choose a TiKV path. so we shouldn't prune other paths.
ds.possibleAccessPaths[0] = selected
ds.possibleAccessPaths = ds.possibleAccessPaths[:1]
// if user wanna tiFlash read, while current heuristic choose a TiKV path. so we shouldn't prune tiFlash path.
keep := ds.preferStoreType&preferTiFlash != 0 && selected.StoreType != kv.TiFlash
if keep {
// also keep tiflash path as well.
ds.possibleAccessPaths = append(ds.possibleAccessPaths, tiflashPath)
return nil
}
ds.possibleAccessPaths[0] = selected
ds.possibleAccessPaths = ds.possibleAccessPaths[:1]
var tableName string
if ds.TableAsName.O == "" {
tableName = ds.tableInfo.Name.O
Expand Down