Github user paul-rogers commented on the issue:
https://github.com/apache/drill/pull/518
Looks like you are right; the JsonParser is more than a simple tokenizer.
We're not the first to try this:
http://stackoverflow.com/questions/37511496/recover-from-malformed-json-with-jackson
(no answer)
I tried an experiment and found that you are on the right track: the way
you are using the JsonParser can be extended to ignore input until the start of
the next object. A quick demonstration:
private static void recover(JsonParser parser) throws IOException {
for ( ; ; ) {
JsonToken token;
try {
token = parser.nextToken();
} catch( JsonParseException e ) { continue; }
if ( token == null ) return;
if ( token != JsonToken.END_OBJECT ) { continue; }
token = parser.nextToken();
if ( token == null ) return;
if ( token == JsonToken.START_OBJECT ) { return; }
}
}
Basically, we keep reading tokens, and ignoring errors, until we
successfully find the } { pair.
As we discussed before, to use the above in Drill, we have to discard the
partly-built record, and start reading the next record assiming the parser is
positioned **after** the START_OBJECT ("{") token, which we've already
consumed. That should be simple.
Still, to do proper recovery, we have to discard the partly-built JSON
record. I've not looked into how to do that. If we don't do that, we return the
bogus partly-built record. Worse, if we recover by trying to build a new
record, we create more partly-built records, but with a different schema,
possibly triggering a schema change event when not really necessary.
Any ideas for how to solve that problem?
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