Example 1 of concurrent SQL and Go

The complete code you write:

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type Rec struct {
    Name string
    Count int64
}

func Select(shard dbid) []Rec
<<
    select 't_node', count(1) 
    from t_node
        union all 
    select 't_tag', count(1) 
    from t_tag 
>>

func Count(numShards int)
{{
    for shard:=1;shard<numShards;shard++ { 
        fmt.Printf("\n=== SHARD: %d ===\n", shard)
        for _,v := range Select(shard) {
            fmt.Printf("%-8s %d\n", v.Name,v.Count)
        }
    }
    return
}}
run

Note: no concurrency here yet!

Instructions

Prerequisites:

• you need Go
• the postgresql database is used, so go get the 'github.com/lib/pq' driver
• Grab the 'amgo' version for your system: see amalegeni-go download

Instructions:

Download and unpack the example1 zipfile that contains the above list code plus more.

First edit the 'setenv.sh', see instructions in the file.

unzip ex1.zip 
cd concsql 
vi setenv.sh 

Now run amgo (amalegeni-go) on the count.amg file:

amgo count.amg 
template/sc.tpl * count.amg 
Generating: src/count/main.go

Compile/install the produced code:

go install count

Before running 'count', edit the 'conf.json' file to configure your database shards:

vi conf.json

Ok. All set to go?

count

# conf.json : 17 shards 
 
=== SHARD: 1 ===
t_node   2123557
t_tag    7072760

=== SHARD: 2 ===
t_node   2626921
t_tag    9253770

=== SHARD: 3 ===
t_node   2708526
t_tag    9232109
..
..