exec: integer division causes a panic

[solongordon]

Vectorized execution panics when you divide an int column by an int constant, presumably because it thinks the result should be an integer but it should actually be a decimal.

root@127.0.0.1:61735/defaultdb> set experimental_vectorize=on;
SET

Time: 281µs

root@127.0.0.1:61735/defaultdb> create table t (x int);
CREATE TABLE

Time: 2.721ms

root@127.0.0.1:61735/defaultdb> insert into t values (1);
INSERT 1

Time: 2.863ms

root@127.0.0.1:61735/defaultdb> select x/2 from t;
E190710 20:17:30.876509 724 sql/conn_executor.go:713  [n1,client=127.0.0.1:61737,user=root] a SQL panic has occurred while executing "SELECT x / 2 FROM t": interface conversion: coldata.column is []int64, not []apd.Decimal
E190710 20:17:30.876569 724 util/log/crash_reporting.go:207  [n1,client=127.0.0.1:61737,user=root] a panic has occurred!
panic: interface conversion: coldata.column is []int64, not []apd.Decimal [recovered]
	panic: panic while executing 1 statements: SELECT _ / _ FROM _; caused by interface conversion: coldata.column is []int64, not []apd.Decimal

goroutine 724 [running]:
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).closeWrapper(0xc00153b600, 0x77fbde0, 0xc00158d640, 0x6bd5e80, 0xc001175710)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:727 +0x330
github.com/cockroachdb/cockroach/pkg/sql.(*Server).ServeConn.func1(0xc00153b600, 0x77fbde0, 0xc00158d640)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:440 +0x61
panic(0x6bd5e80, 0xc001175710)
	/usr/local/Cellar/go/1.12.6/libexec/src/runtime/panic.go:522 +0x1b5
github.com/cockroachdb/cockroach/pkg/sql/exec/coldata.(*memColumn).Decimal(0xc001176dc0, 0x0, 0x785df60, 0xc001176dc0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/exec/coldata/vec.go:226 +0x74
github.com/cockroachdb/cockroach/pkg/sql/distsqlrun.(*materializer).Next(0xc000926e00, 0x59b2eb3, 0xc0011753e0, 0xc001bc2290, 0x5a5a4de)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsqlrun/materializer.go:166 +0xb87
github.com/cockroachdb/cockroach/pkg/sql/distsqlrun.Run(0x77fbea0, 0xc001175200, 0x78079e0, 0xc000926e00, 0x77d87e0, 0xc001430000)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsqlrun/base.go:171 +0x35
github.com/cockroachdb/cockroach/pkg/sql/distsqlrun.(*ProcessorBase).Run(0xc000926e00, 0x77fbea0, 0xc001175200)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsqlrun/processors.go:793 +0x92
github.com/cockroachdb/cockroach/pkg/sql/distsqlrun.(*Flow).Run(0xc0001232c0, 0x77fbea0, 0xc001175200, 0x713a620, 0x0, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsqlrun/flow.go:654 +0x1f2
github.com/cockroachdb/cockroach/pkg/sql.(*DistSQLPlanner).Run(0xc0001e8fc0, 0xc001aca960, 0xc0014ba240, 0xc001bc28b0, 0xc001430000, 0xc00153ba28, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql_running.go:295 +0x35c
github.com/cockroachdb/cockroach/pkg/sql.(*DistSQLPlanner).PlanAndRun(0xc0001e8fc0, 0x77fbea0, 0xc001174c90, 0xc00153ba28, 0xc001aca960, 0xc0014ba240, 0x77fdba0, 0xc0014aad80, 0xc001430000)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/distsql_running.go:859 +0x208
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).execWithDistSQLEngine(0xc00153b600, 0x77fbea0, 0xc001174c90, 0xc00153b950, 0x3, 0xfa19d18, 0xc0007bf8c0, 0xc001bc2b01, 0x0, 0x0, ...)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:902 +0x370
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).dispatchToExecutionEngine(0xc00153b600, 0x77fbea0, 0xc001174c90, 0xc00153b950, 0xfa19d18, 0xc0007bf8c0, 0x0, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:734 +0x6e5
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).execStmtInOpenState(0xc00153b600, 0x77fbea0, 0xc001174c90, 0x78013a0, 0xc001118740, 0xc0015531ee, 0x11, 0x0, 0x1, 0x0, ...)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:417 +0xb64
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).execStmt(0xc00153b600, 0x77fbea0, 0xc001174c90, 0x78013a0, 0xc001118740, 0xc0015531ee, 0x11, 0x0, 0x1, 0x0, ...)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor_exec.go:99 +0x4ec
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).execCmd(0xc00153b600, 0x77fbde0, 0xc001176780, 0x0, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:1204 +0x1ab0
github.com/cockroachdb/cockroach/pkg/sql.(*connExecutor).run(0xc00153b600, 0x77fbde0, 0xc00158d640, 0xc00010e340, 0x5400, 0x15000, 0xc00010e3d8, 0xc000087160, 0x0, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:1140 +0x1a3
github.com/cockroachdb/cockroach/pkg/sql.(*Server).ServeConn(0xc0001ddb00, 0x77fbde0, 0xc00158d640, 0xc00153b600, 0x5400, 0x15000, 0xc00010e3d8, 0xc000087160, 0x0, 0x0)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/conn_executor.go:442 +0xce
github.com/cockroachdb/cockroach/pkg/sql/pgwire.(*conn).processCommandsAsync.func1(0xc00167c299, 0xc00162e860, 0x77fbde0, 0xc00158d640, 0xc000087160, 0xc0001ddb00, 0xc00176e000, 0x77ff920, 0xc00162e840, 0xc0015674a0, ...)
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/pgwire/conn.go:580 +0x21c
created by github.com/cockroachdb/cockroach/pkg/sql/pgwire.(*conn).processCommandsAsync
	/Users/solon/go/src/github.com/cockroachdb/cockroach/pkg/sql/pgwire/conn.go:509 +0x17b

[solongordon]

I think we just need some more column_exec_setup to bail out if types don't match.

[jordanlewis]

Yeah I think that's probably right. There's a separate missing feature that's kind of related which is mixed-type comparison. This is a mixed-type binary operator. I think eventually we'll need to improve the execgen code to know how to generate all of these - at the moment it's fairly hard coded to a single type.