## What changes were proposed in this pull request?
`ColumnVector`s store string data in one big byte array. Since the array size is capped at just under Integer.MAX_VALUE, a single `ColumnVector` cannot store more than 2GB of string data.
But since the Parquet files commonly contain large blobs stored as strings, and `ColumnVector`s by default carry 4096 values, it's entirely possible to go past that limit. In such cases a negative capacity is requested from `WritableColumnVector.reserve()`. The call succeeds (requested capacity is smaller than already allocated capacity), and consequently `java.lang.ArrayIndexOutOfBoundsException` is thrown when the reader actually attempts to put the data into the array.
This change introduces a simple check for integer overflow to `WritableColumnVector.reserve()` which should help catch the error earlier and provide more informative exception. Additionally, the error message in `WritableColumnVector.throwUnsupportedException()` was corrected, as it previously encouraged users to increase rather than reduce the batch size.
## How was this patch tested?
New units tests were added.
Author: Ala Luszczak <ala@databricks.com>
Closes#21206 from ala/overflow-reserve.
8bd27025b7