executor: set the txn provider before building plan in 'show columns'

[tangenta]

What problem does this PR solve?

Issue Number: close #36426.

Problem Summary:

The problem is from txnManager's "context provider not set". Here is the stack trace:

session.(*txnManager).GetStmtReadTS (txnmanager.go:72) github.com/pingcap/tidb/session
executor.(*executorBuilder).getSnapshotTS (builder.go:1594) github.com/pingcap/tidb/executor
executor.buildNoRangeTableReader (builder.go:3168) github.com/pingcap/tidb/executor
executor.(*executorBuilder).buildTableReader (builder.go:3263) github.com/pingcap/tidb/executor
executor.(*executorBuilder).build (builder.go:277) github.com/pingcap/tidb/executor
executor.(*executorBuilder).buildTopN (builder.go:1917) github.com/pingcap/tidb/executor
executor.(*executorBuilder).build (builder.go:241) github.com/pingcap/tidb/executor
executor.(*executorBuilder).buildStreamAgg (builder.go:1499) github.com/pingcap/tidb/executor
executor.(*executorBuilder).build (builder.go:263) github.com/pingcap/tidb/executor
executor.(*executorBuilder).buildMaxOneRow (builder.go:2025) github.com/pingcap/tidb/executor
executor.(*executorBuilder).build (builder.go:273) github.com/pingcap/tidb/executor
executor.init.1.func1 (executor.go:1427) github.com/pingcap/tidb/executor
core.(*expressionRewriter).handleScalarSubquery (expression_rewriter.go:1030) github.com/pingcap/tidb/planner/core
core.(*expressionRewriter).Enter (expression_rewriter.go:409) github.com/pingcap/tidb/planner/core
ast.(*SubqueryExpr).Accept (expressions.go:391) github.com/pingcap/tidb/parser/ast
ast.(*BinaryOperationExpr).Accept (expressions.go:217) github.com/pingcap/tidb/parser/ast
core.(*PlanBuilder).rewriteExprNode (expression_rewriter.go:199) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).rewriteWithPreprocess (expression_rewriter.go:145) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).rewrite (expression_rewriter.go:113) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).buildSelection (logical_plan_builder.go:1000) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).buildSelect (logical_plan_builder.go:3892) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).Build (planbuilder.go:718) github.com/pingcap/tidb/planner/core
core.(*PlanBuilder).BuildDataSourceFromView (logical_plan_builder.go:4837) github.com/pingcap/tidb/planner/core
executor.tryFillViewColumnType.func1 (show.go:2066) github.com/pingcap/tidb/executor
executor.runWithSystemSession (show.go:2092) github.com/pingcap/tidb/executor
executor.tryFillViewColumnType (show.go:2063) github.com/pingcap/tidb/executor
executor.(*ShowExec).fetchShowColumns (show.go:624) github.com/pingcap/tidb/executor
executor.(*ShowExec).fetchAll (show.go:149) github.com/pingcap/tidb/executor
executor.(*ShowExec).Next (show.go:116) github.com/pingcap/tidb/executor
executor.Next (executor.go:319) github.com/pingcap/tidb/executor
executor.(*ExecStmt).next (adapter.go:898) github.com/pingcap/tidb/executor
executor.(*recordSet).Next (adapter.go:152) github.com/pingcap/tidb/executor
<autogenerated>:2
server.(*tidbResultSet).Next (driver_tidb.go:405) github.com/pingcap/tidb/server
server.(*clientConn).writeChunks (conn.go:2250) github.com/pingcap/tidb/server
server.(*clientConn).writeResultset (conn.go:2200) github.com/pingcap/tidb/server
server.(*clientConn).handleStmt (conn.go:2081) github.com/pingcap/tidb/server
server.(*clientConn).handleQuery (conn.go:1913) github.com/pingcap/tidb/server
server.(*clientConn).dispatch (conn.go:1397) github.com/pingcap/tidb/server
server.(*clientConn).Run (conn.go:1142) github.com/pingcap/tidb/server
server.(*Server).onConn (server.go:563) github.com/pingcap/tidb/server
server.(*Server).startNetworkListener.func2 (server.go:454) github.com/pingcap/tidb/server
runtime.goexit (asm_arm64.s:1259) runtime
 - Async Stack Trace
server.(*Server).startNetworkListener (server.go:454) github.com/pingcap/tidb/server

To get the accurate field types of a view, we need to build a plan for the SQL in the view(see tryFillViewColumnType). An internal session is used to build the plan to prevent concurrent access to the same sesssion(this can happen in join scenarios, see #32459).

The transaction context is not needed in normal cases. However, for the views that contain scalar subquery, an executor is built and run for the scalar subquery evaluation, which requires a startTS from the transaction. Because no transaction is set before using the system session, the error "context provider not set" occurs.

What is changed and how it works?

We can solve the issue by setting up a new transaction before using the internal session.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• xhebox

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[xhebox]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 5303ab7

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/5303ab7a754374a8ec30f3a70f4c7cc7ecd7ba5e

[xiongjiwei]

/hold

[tangenta]

The issue will be closed by #36613.