Paging, and MapScan or SliceMap

[herbert...@crossengage.io]

Hi,

I'm doing a small utility that needs to go through all rows of one Cassandra table, without knowing previously the schema of such table.

For that it looks like MapScan or SliceMap were what I needed, but:

1) MapScan works, but only returns the first row, even if PageSize has, let's say, 1000 rows.
2) I don't get how to use SliceMap with Iter and pages.

Do you guys have made something like this before in gocql?

best,

Herbert

[Dan Kinder]

Hi Herbert,

I'm not quite sure what you mean about MapScan returning only the first row, here is how we have used it to select many rows:

    values = map[string]interface{}{}                                                                                       

    iter = db.Query("SELECT * FROM my_table").Iter()                                                  

    for iter.MapScan(values) {                                                                                               

        doStuff(values)                                                                                

        values = map[string]interface{}{}                                                                                   

    }                                                                                                                       

    err = iter.Close()

--
You received this message because you are subscribed to the Google Groups "gocql" group.
To unsubscribe from this group and stop receiving emails from it, send an email to gocql+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

--

Dan Kinder
Principal Software Engineer
Turnitin – www.turnitin.com
dki...@turnitin.com

[Herbert Fischer]

Hi,

Thanks for the example. The last line was crucial to understand why MapScan was returning only one row.

2016/10/31 18:04:02 can not unmarshal X uuid into gocql.UUID

Now it's another issue I'll have to go through.

On 31 October 2016 at 17:41, Dan Kinder <dki...@turnitin.com> wrote:

Hi Herbert,

I'm not quite sure what you mean about MapScan returning only the first row, here is how we have used it to select many rows:

    values = map[string]interface{}{}                                                                                       

    iter = db.Query("SELECT * FROM my_table").Iter()                                                  

    for iter.MapScan(values) {                                                                                               

        doStuff(values)                                                                                

        values = map[string]interface{}{}                                                                                   

    }                                                                                                                       

    err = iter.Close()

On Mon, Oct 31, 2016 at 9:27 AM, <herbert.fischer@crossengage.io> wrote:

Hi,

I'm doing a small utility that needs to go through all rows of one Cassandra table, without knowing previously the schema of such table.

For that it looks like MapScan or SliceMap were what I needed, but:

1) MapScan works, but only returns the first row, even if PageSize has, let's say, 1000 rows.
2) I don't get how to use SliceMap with Iter and pages.

Do you guys have made something like this before in gocql?

best,

Herbert

--
You received this message because you are subscribed to the Google Groups "gocql" group.
To unsubscribe from this group and stop receiving emails from it, send an email to gocql+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

--

Dan Kinder
Principal Software Engineer
Turnitin – www.turnitin.com
dki...@turnitin.com

--

Herbert Fischer | Senior IT Architect
CrossEngage GmbH | Gontardstraße 11 | 10178 Berlin

E-Mail: herbert...@crossengage.io

Web: www.crossengage.io

Amtsgericht Berlin-Charlottenburg | HRB 169537 B
Geschäftsführer: Dr. Markus Wübben, Manuel Hinz | USt-IdNr.: DE301504202