sql: error caused by collated string comparison

[rafiss]

Describe the problem

A normal SELECT query over collated strings can cause an error. A customer bug report also claims there was a panic and node crash.

Even if only collatedstring{en-US-u-ks-level2} is used, the error message says that the query doesn't work because it thinks collatedstring{en-us-u-ks-level2} is being used.

ERROR: internal error: "$0" = 'bbb' COLLATE en_us_u_ks_level2: unsupported comparison operator: <collatedstring{en-US-u-ks-level2}> = <collatedstring{en_us_u_ks_level2}>
SQLSTATE: XX000
DETAIL: stack trace:
/go/src/github.com/cockroachdb/cockroach/pkg/sql/execinfra/expr.go:78: processExpression()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/execinfra/expr.go:162: Init()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/execinfra/processorsbase.go:108: Init()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/execinfra/processorsbase.go:805: InitWithEvalCtx()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/execinfra/processorsbase.go:775: Init()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/rowexec/tablereader.go:95: newTableReader()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/rowexec/processors.go:138: NewProcessor()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/rowflow/row_based_flow.go:228: makeProcessor()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/rowflow/row_based_flow.go:81: setupProcessors()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/rowflow/row_based_flow.go:64: Setup()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql/server.go:366: setupFlow()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql/server.go:480: SetupLocalSyncFlow()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql_running.go:265: setupFlows()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql_running.go:388: Run()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql_running.go:1008: PlanAndRun()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:903: execWithDistSQLEngine()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:800: dispatchToExecutionEngine()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:488: execStmtInOpenState()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:99: execStmt()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:1356: execCmd()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:1285: run()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:490: ServeConn()
/go/src/github.com/cockroachdb/cockroach/pkg/sql/pgwire/conn.go:595: func1()
/usr/local/go/src/runtime/asm_amd64.s:1357: goexit()

To Reproduce

CREATE TABLE nocase_strings (s STRING COLLATE "en-US-u-ks-level2");
INSERT INTO nocase_strings VALUES ('Aaa' COLLATE "en-US-u-ks-level2"), ('Bbb' COLLATE "en-US-u-ks-level2");
SELECT s FROM nocase_strings WHERE s = ('bbb' COLLATE "en-US-u-ks-level2");

Environment:
v20.1

Additional context
The error seems fixed in v20.2.0-alpha.2

[rafiss]

Actually this also fails in logic tests on 20.2, with the fakedist config. This comment explains why #56267 (comment)

[mgartner]

It looks like this is bug still exists. The logic tests below cause the same internal error. However, the I can't get the same SQL to produce an error in cockroach demo.

statement ok
CREATE TABLE nocase_strings (
  i INT,
  s STRING COLLATE "en-US-u-ks-level2"
);

statement ok
INSERT INTO nocase_strings VALUES (1, 'Aaa' COLLATE "en-US-u-ks-level2"), (2, 'Bbb' COLLATE "en-US-u-ks-level2");

If i is removed from the table, there is no internal error.

cc @rafiss