lightning: fail to import data into tables with expression index enabled

[lichunzhu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

use lightning to import these data into a tidb cluster with tidb's experimental.allow-expression-index setting to true.

test.t-schema.sql

/*!40101 SET NAMES binary*/;
CREATE TABLE `t` (
  `a` bigint(30) NOT NULL,
  `b` varchar(40) NOT NULL DEFAULT uuid(),
  UNIQUE KEY `c` (`b`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

test.t.0000000.csv

/!40101 SET NAMES binary/;
"a"
1
2
3
4
5

2. What did you expect to see? (Required)

Lightning can import these data and generate uuid for column b successfully.

mysql> select * from t;
+---+--------------------------------------+
| a | b                                    |
+---+--------------------------------------+
| 1 | 224bb472-05a3-11ee-91e8-b28e57435a9e |
| 2 | 224bb95e-05a3-11ee-91e8-b28e57435a9e |
| 3 | 224bba1c-05a3-11ee-91e8-b28e57435a9e |
| 4 | 224bba9e-05a3-11ee-91e8-b28e57435a9e |
| 5 | 224bbb0c-05a3-11ee-91e8-b28e57435a9e |
+---+--------------------------------------+
5 rows in set (0.00 sec)

3. What did you see instead (Required)

Lightning panics.

$ tiup tidb-lightning:v6.5.2 -c /Users/chauncy/code/goPath/src/github.com/pingcap/tidb/bin/lightning_e2e.toml 
Starting component `tidb-lightning`: /Users/chauncy/.tiup/components/tidb-lightning/v6.5.2/tidb-lightning -c /Users/chauncy/code/goPath/src/github.com/pingcap/tidb/bin/lightning_e2e.toml
Verbose debug logs will be written to /var/folders/5m/9r5zk5b942b4ktht2_5rklfr0000gn/T/lightning.log.2023-06-08T10.21.34+0800

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x91 pc=0x10470de90]

goroutine 322 [running]:
github.com/pingcap/tidb/sessionctx/variable.(*SessionVars).IsPessimisticReadConsistency(...)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/sessionctx/variable/session.go:1990
github.com/pingcap/tidb/planner/core.(*PlanBuilder).Init(0x14000d45d40, {0x105ca4500, 0x14000a96480}, {0x0?, 0x0}, 0x14000c66400)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/planner/core/planbuilder.go:730 +0x180
github.com/pingcap/tidb/planner/core.rewriteAstExpr({0x105ca4500, 0x14000a96480}, {0x105c5c5f8, 0x14000e64120}, 0x0, {0x0, 0x0, 0x0})
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/planner/core/expression_rewriter.go:72 +0xb0
github.com/pingcap/tidb/planner/core.evalAstExpr({0x105ca4500?, 0x14000a96480?}, {0x105c5c5f8?, 0x14000e64120?})
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/planner/core/expression_rewriter.go:58 +0xc8
github.com/pingcap/tidb/table.getColDefaultExprValue({0x105ca4500, 0x14000a96480}, 0x48?, {0x14000e4a970?, 0x0?})
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/table/column.go:527 +0x118
github.com/pingcap/tidb/table.GetColDefaultValue({0x105ca4500?, 0x14000a96480?}, 0x5?)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/table/column.go:503 +0xbc
github.com/pingcap/tidb/br/pkg/lightning/backend/kv.(*tableKVEncoder).getActualDatum(0x140010c41e0, 0x1, 0x1, 0x0)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/backend/kv/sql2kv.go:509 +0x3e0
github.com/pingcap/tidb/br/pkg/lightning/backend/kv.(*tableKVEncoder).Encode(0x140010c41e0, {0x14000e9a390?}, {0x14000bcd200?, 0x1, 0x10}, 0x1, {0x14000e4e528, 0x3, 0x14001145588?}, {0x102a49728?, ...}, ...)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/backend/kv/sql2kv.go:377 +0x1b0
github.com/pingcap/tidb/br/pkg/lightning/restore.(*chunkRestore).encodeLoop(0x14000f24e20, {0x105c3a928, 0x14000cb8d80}, 0xc?, 0x14000a96880, {0x10296d93c?}, {0x105c1f560, 0x140010c41e0}, 0x0?, 0x1400034d6c0)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/restore/restore.go:2690 +0xa2c
github.com/pingcap/tidb/br/pkg/lightning/restore.(*chunkRestore).restore(0x14000f24e20, {0x105c3a928, 0x14000cb8d80}, 0x14000a96880, 0x0, 0x14000f24e40, 0x14000cb0020, 0x1400034d6c0)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/restore/restore.go:2787 +0x4c0
github.com/pingcap/tidb/br/pkg/lightning/restore.(*TableRestore).restoreEngine.func3(0x1400072dc20?, 0x14000f24e20)
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/restore/table_restore.go:582 +0x148
created by github.com/pingcap/tidb/br/pkg/lightning/restore.(*TableRestore).restoreEngine
        /Users/pingcap/workspace/build-common/go/src/github.com/pingcap/br/br/pkg/lightning/restore/table_restore.go:572 +0xb84

4. What is your TiDB version? (Required)

master/v6.5.2 all have this problem