Project

hsql

0.01
No commit activity in last 3 years
No release in over 3 years
Write SQL queries with Mustache and easily render them for specific dates/times
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 Dependencies

Development

~> 1.10
> 0
~> 3.3
= 0.37.2
~> 0.8.0

Runtime

 Project Readme

HSQL

"Hash (of data) and SQL" is a library that parses .sql files with YAML front matter. This allows analysts and other non-developers to write and develop ETLs without having to write source code but still giving them the power of specifying variables to interpolate into the SQL and other metadata that the program executing the SQL can use.

How to use this

Rather than specifying variables and metadata for a set of database queries in a .rb,.py or other programming language source file the queries should be written into a .sql file directly.

# filename: daily_summary.sql
owner: jackdanger
schedule: hourly
environments:
  production:
    output_table: summaries
    update_condition:
  development:
    output_table: jackdanger_summaries
    update_condition: WHERE 1 <> 1
---
INSERT INTO {{{output_table}}} SELECT * FROM interesting_information;
UPDATE summaries_performed SET complete = 1 {{{update_condition}}};

The above is a .sql file and any text editor will allow analysts to use code completion and syntax highlighting for their queries.

The data hash in the YAML front matter lists a set of variables, by environment, that can be interpolated into the SQL queries. To render the queries an environment must be provided. The templating system used for interpolating data is Mustache (though theoretically we could use any templating system).

Rendering SQL on the command line

$ hsql daily_summary.sql -env development
USE some_database;
INSERT INTO jackdanger_summaries SELECT * FROM interesting_information;
UPDATE summaries_performed SET complete = 1 WHERE 1 <> 1;

The hsql command-line utility outputs valid Postgres SQL with any template variables filled in from the YAML data. To access the metadata directly use the --yaml or --json flag

$ hsql daily_summary.sql -env development --json
{"owner":"jackdanger","schedule":"hourly","output_table":"jackdanger_summaries","update_condition":"WHERE 1 <> 1"}
$ hsql daily_summary.sql -env development --yaml
---
owner: jackdanger
schedule: hourly
output_table: jackdanger_summaries
update_condition: WHERE 1 <> 1

Working with times and dates

By default when you run the hsql command it will set the template variable {{{ now }}} to the current moment (as per the local machine's clock). You can modify this by setting a --timestamp command line flag to any Ruby-parseable time or date string and that will be used to establish the value of {{{ now }}}.

To avoid having to do date math in SQL all of the following are also available in every template, relative to the value of {{{ now }}}:

                              "now" => "'2015-10-06 12:34:55 -0700'",
                "beginning_of_hour" => "'2015-10-06 12:00:00 -0700'",
                 "beginning_of_day" => "'2015-10-06 00:00:00 -0700'",
                "beginning_of_week" => "'2015-10-05 00:00:00 -0700'",
               "beginning_of_month" => "'2015-10-01 00:00:00 -0700'",
             "beginning_of_quarter" => "'2015-10-01 00:00:00 -0700'",
                "beginning_of_year" => "'2015-01-01 00:00:00 -0800'",
                      "end_of_hour" => "'2015-10-06 12:59:59 -0700'",
                       "end_of_day" => "'2015-10-06 23:59:59 -0700'",
                      "end_of_week" => "'2015-10-11 23:59:59 -0700'",
                     "end_of_month" => "'2015-10-31 23:59:59 -0700'",
                   "end_of_quarter" => "'2015-12-31 23:59:59 -0800'",
                      "end_of_year" => "'2015-12-31 23:59:59 -0800'",
       "beginning_of_previous_hour" => "'2015-10-06 11:00:00 -0700'",
             "end_of_previous_hour" => "'2015-10-06 11:59:59 -0700'",
        "beginning_of_previous_day" => "'2015-10-05 00:00:00 -0700'",
              "end_of_previous_day" => "'2015-10-05 23:59:59 -0700'",
       "beginning_of_previous_week" => "'2015-09-28 00:00:00 -0700'",
             "end_of_previous_week" => "'2015-10-04 23:59:59 -0700'",
      "beginning_of_previous_month" => "'2015-09-01 00:00:00 -0700'",
            "end_of_previous_month" => "'2015-09-30 23:59:59 -0700'",
    "beginning_of_previous_quarter" => "'2015-07-01 00:00:00 -0700'",
          "end_of_previous_quarter" => "'2015-09-30 23:59:59 -0700'",
       "beginning_of_previous_year" => "'2014-01-01 00:00:00 -0800'",
             "end_of_previous_year" => "'2014-12-31 23:59:59 -0800'"

Programmatic Ruby API

If you'd like to manipulate the queries in some advanced way (e.g. to modify the AST of a parsed query) you can use the gem as a dependency.

>> require 'hsql'
>> file = HSQL::File.parse_file('./simple.sql', 'development')
>> query = file.queries.first;
>> query.to_s
=> "INSERT INTO jackdanger_summaries SELECT count(*) FROM interesting_information"
>> query.ast
=> {
    "INSERT INTO" => {
             "relation" => {
            "RANGEVAR" => {
                    "schemaname" => nil,
                       "relname" => "jackdanger_summaries",
                        "inhOpt" => 2,
                "relpersistence" => "p",
                         "alias" => nil,
                      "location" => 13
            }
        },
                 "cols" => nil,
           "selectStmt" => {
            "SELECT" => {
                "distinctClause" => nil,
                    "intoClause" => nil,
                    "targetList" => [
                    [0] {
                        "RESTARGET" => {
                                   "name" => nil,
                            "indirection" => nil,
                                    "val" => {
                                "FUNCCALL" => {
                                            "funcname" => [
                                        [0] "count"
                                    ],
                                                "args" => nil,
                                           "agg_order" => nil,
                                          "agg_filter" => nil,
                                    "agg_within_group" => false,
                                            "agg_star" => true,
                                        "agg_distinct" => false,
                                       "func_variadic" => false,
                                                "over" => nil,
                                            "location" => 79
                                }
                            },
                               "location" => 79
                        }
                    }
                ],
                    "fromClause" => [
                    [0] {
                        "RANGEVAR" => {
                                "schemaname" => nil,
                                   "relname" => "interesting_information",
                                    "inhOpt" => 2,
                            "relpersistence" => "p",
                                     "alias" => nil,
                                  "location" => 95
                        }
                    }
                ],
                   "whereClause" => nil,
                   "groupClause" => nil,
                  "havingClause" => nil,
                  "windowClause" => nil,
                   "valuesLists" => nil,
                    "sortClause" => nil,
                   "limitOffset" => nil,
                    "limitCount" => nil,
                 "lockingClause" => nil,
                    "withClause" => nil,
                            "op" => 0,
                           "all" => false,
                          "larg" => nil,
                          "rarg" => nil
            }
        },
        "returningList" => nil,
           "withClause" => nil
    }
}
>> query.ast['INSERT INTO']['relation']['RANGEVAR']['relname'] = 'othertable'
=> "othertable"
>> query.to_s
=> "INSERT INTO othertable SELECT count(*) FROM interesting_information"

Please don't hesitate to open a PR or issue for any reason. New contributors and bug fixes are welcome. Forks of this project will be celebrated.