[SQL][Java] Fluid query builder

[kennknowles]

Create a fluid query builder.

 

Problem:

SQL queries as java strings are very hard to read and debug. See examples below.

 

Solution:

Fluid query builder, along the lines of:

QueryTransform query = 
  QueryBuilder
    .from(pcollection)
    .where(e -> e.id == 3)
    .groupBy(e
-> e.name)
    .select();

 

Examples:

    String sql = "select f_int2, count(*) as getFieldCount, "
        + "sum(f_long) as sum1, avg(f_long)
as avg1, max(f_long) as max1, min(f_long) as min1, "
        + "sum(f_short) as sum2, avg(f_short)
as avg2, max(f_short) as max2, min(f_short) as min2, "
        + "sum(f_byte) as sum3, avg(f_byte)
as avg3, max(f_byte) as max3, min(f_byte) as min3, "
        + "sum(f_float) as sum4, avg(f_float)
as avg4, max(f_float) as max4, min(f_float) as min4, "
        + "sum(f_double) as sum5, avg(f_double)
as avg5, "
        + "max(f_double) as max5, min(f_double) as min5, "
        + "max(f_timestamp)
as max6, min(f_timestamp) as min6, "
        + "var_pop(f_double) as varpop1, var_samp(f_double) as
varsamp1, "
        + "var_pop(f_int) as varpop2, var_samp(f_int) as varsamp2 "
        + "FROM TABLE_A
group by f_int2";

or

    String sql = "SELECT "
        + " order_id, site_id, count(*) as cnt "
        + "FROM ORDER_DETAILS
GROUP BY order_id, site_id"
        + ", TUMBLE(order_time, INTERVAL '1' HOUR) "
        + " UNION
SELECT "
        + " order_id, site_id, count(*) as cnt "
        + "FROM ORDER_DETAILS GROUP BY order_id,
site_id"
        + ", TUMBLE(order_time, INTERVAL '2' HOUR) ";

or

    cli.execute(
        "create table person (\n"
        + "id int COMMENT 'id', \n"
        +
"name varchar(31) COMMENT 'name', \n"
        + "age int COMMENT 'age') \n"
        + "TYPE 'text'
\n"
        + "COMMENT '' LOCATION 'text://home/admin/orders'"
    );

Imported from Jira BEAM-3548. Original Jira may contain additional context.
Reported by: kedin.