Adding support for Impala data types.

[edgararuiz-zz]

Impala does not have a date type so mapping it to varchar

[jimhester]

From Magnitude's documentation it does look like there is a DATE type, and looks like STRING should be CHAR?

I just pushed a commit (ef071fd) that exposes a test_roundtrip() function, which will try to roundtrip a data frame with all of the data types supported by the odbc package. Could you try impala with that to verify this method is correct for all data types? It is un-exported so you will need to use odbc:::test_roundtrip(con) to run it.

[edgararuiz-zz]

Here's the article that discusses the differences between HiveQL and Impala: https://www.cloudera.com/documentation/enterprise/5-8-x/topics/impala_langref_unsupported.html#langref_hiveql_unsupported

[edgararuiz-zz]

Test results:

Error: Test failed: '[Impala] round tripping data.frames works' * <SQL> 'CREATE TABLE `it` ( `datetime` TIMESTAMP, `date` DATE, `binary` BINARY, `integer` INTEGER, `double` DOUBLE, `character` VARCHAR(255), `logical` VARCHAR(5) ) ' nanodbc.cpp:1587: HY000: [RStudio][ImpalaODBC] (110) [HY000] : ImpalaRuntimeException: CAUSED BY: InvalidObjectException: Invalid column type: invalid_type 1: DBI::dbWriteTable(con, "it", it, overwrite = TRUE) 2: DBI::dbWriteTable(con, "it", it, overwrite = TRUE) 3: .local(conn, name, value, ...) 4: dbGetQuery(conn, sql) 5: dbGetQuery(conn, sql) 6: dbSendQuery(conn, statement, ...) 7: dbSendQuery(conn, statement, ...) 8: OdbcResult(connection = conn, statement = statement) 9: new_result(connection@ptr, statement)

[jimhester]

Thanks Edgar!