Yes, it is possible to query the backend Metastore DB directly, but the query might turn out to be rather elaborate because you need to cover the following stats that are interesting to Impala: 1. Table level row count 2. Partition level row counts 3. Column level stats such as NDV ... View more

Thanks for following up! Do you mind summarizing the changes you made to fix it so others can benefit from your solution? ... View more

It's generally safe to use name-based resolution by default. Performance should be about the same. I agree name-based resolution may be a better choice because it's more intuitive.   Index vs. name based resolution have different tradeoffs in terms of what schema-evolution operations are allowed. For example with index-based resolution you can safely rename a column in your table schema. With name based resolution you can safely add/drop columns in the middle of your table schema, whereas with index-based resolution you can generally only add new columns at the end. So it's really all about tradeoffs. ... View more

Impala does not fully support Unicode. See "Character Sets" here: https://www.cloudera.com/documentation/enterprise/latest/topics/impala_string.html   That said, reading/writing UTF-8 should work in most circumstances. Is your data in UTF-8 or a different representation of Unicode? Other encodings will likely not work at all.   Do queries using the Impala Shell return expected results?   ... View more

Please also see my response on the JIRA. In addition:   The fact that the JIRA is old has no bearing on priority. We prioritize according to the needs of our users. We have limited resources and make difficult choices on what to work on. ... View more

That currently is not possible, sorry.   Please see the corresponding JIRA for workarounds: https://issues.apache.org/jira/browse/IMPALA-110   In particular, using NDV() iinstead of COUNT(DISTINCT) is much faster, but returns approximate results only. ... View more

Thanks for following up! Glad you got it working. ... View more

Your steps were perfectly reasonable - this flow should work.   Agree, the EXPLAIN definitely looks suspicious.   You can get the location via SHOW CREATE TABLE <table>.   Perhaps there is an issue with mixed-case HDFS paths. You might try converting everything to lower case to see if it works. I'd love to know either way so I can file a bug and fix it 🙂   Thanks!   ... View more

Sorry for the trouble - this is expected to work.   Can you provide the query profile of the query that returned 0 rows? ... View more