Interrupted sqlite: prepare can return SQL logic error on interrupted connection

[davidjb]

I'm using sqlitex in a concurrent-execution environment to SELECT data from a single SQLite database on the file system and it's going well (thank you for your efforts!). Up to 100 executions are run concurrently in context with a timeout of 10s, after which any results get collated and handed off, and any interrupt errs are ignored. Non-interrupt errors are treated as fatal and exit the parent process. SQL executions work fine up until the timeout occurs, after which I check for interruption like so:

func ShouldStop(err error) bool {
	return sqlite.ErrCode(err) == sqlite.ResultInterrupt || errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled)
}

and this works almost all of the time. However, it seems that an interrupt at particular moments may not yield sqlite.ResultInterrupt, instead very occasionally erroring like so:

sqlite: prepare "... (SELECT * FROM json_each(:input))) ...": SQL logic error: vtable constructor failed: json_each

The surrounding context has been cancelled at this point due to timeout, and ShouldStop called to check the err, but it's not an sqlite.ResultInterrupt so becomes fatal. I've truncated the rather long SQL query, but suffice to say that it has multiple SELECT * FROM json_each(:xyz) calls in it accessing separate bind parameters, and these are the only calls I'm making to json_each.

The underlying SQLite file is fine on the file system - it's been being queried en masse successfully for the previous 10s and only the executions still running post-deadline return errors like this. In the above error, 6 interrupted goroutines all errored in the same manner, sqlite: prepare: "...": SQL logic error: vtable constructor failed: json_each.

I've tried creating an isolated test case to replicate this (with race conditions cancelling the ctx and/or closing the SetInterrupt channel at varying times) but haven't successfully triggered an SQL logic error out of

go-sqlite/sqlite.go

Line 468 in f1ff619

return nil, fmt.Errorf("sqlite: prepare %q: %w", query, err)

- only sqlite: prepare: interrupted and sqlite: step: interrupted thus far.

I'm using the following versions:

require zombiezen.com/go/sqlite v1.4.2

require (
	...
	modernc.org/libc v1.65.7 // indirect
	modernc.org/mathutil v1.7.1 // indirect
	modernc.org/memory v1.11.0 // indirect
	modernc.org/sqlite v1.37.1 // indirect
)

[zombiezen]

Hm. AFAICT this would be an issue in SQLite upstream, unless you have evidence that there's a place where the library is swallowing the error code. (See #133 for a recent example of this.)