ReadColumnByPath signature takes int not int64

[nickpoorman]

is there any reason why ReadColumnByPathReadColumnByPath takes an int for the number of columns to read?

parquet-go/reader/columnreader.go

Line 63 in 6d4d798

func (self *ParquetReader) ReadColumnByPath(pathStr string, num int) (values []interface{}, rls []int32, dls []int32, err error) {

In order to use this, the developer has to covert the number of rows to int before passing them in and then they get converted back to int64 again inside ReadColumnByPathReadColumnByPath.

To use:

num := int(pr.GetNumRows())
values, _, _, err := pr.ReadColumnByPath("some.path", num)

Converted back to int64 inside ReadColumnByPathReadColumnByPath:

parquet-go/reader/columnreader.go

Line 83 in 6d4d798

table, _ := cb.ReadRows(int64(num))

In order to use this safely, I now need to also add some logic to check the size of int on the system it's running on.

if strconv.IntSize != 64 {
    log.Printf("Warning: you are running this on a 32-bit system. Possible overflow if number of rows exceeds: %d. Number of rows: %d", math.MaxInt32, pr.GetNumRows())
}

[xitongsys]

hi, @nickpoorman
no specific reasons and i fixed it in latest version. please check it.

[nickpoorman]

Looks good! Thanks.