CREATE SOURCE: Load generator

CREATE SOURCE connects Materialize to an external system you want to read data from, and provides details about how to decode and interpret that data.

Load generator sources produce synthetic data for use in demos and performance tests.

Syntax

load_generator_option

WITH options

Description

Materialize has several built-in load generators, which provide a quick way to get up and running with no external dependencies before plugging in your own data sources. If you would like to see an additional load generator, please submit a feature request.

Counter

The counter load generator produces the sequence 1, 2, 3, …. Each tick interval, the next number in the sequence is emitted.

Auction

The auction load generator simulates an auction house, where users are bidding on an ongoing series of auctions. The auction source will be automatically demuxed into multiple subsources when the CREATE SOURCE command is executed. This will create the following subsources:

• organizations describes the organizations known to the auction house.

  Field	Type	Description
  id	bigint	A unique identifier for the organization.
  name	text	The organization’s name.

• users describes the users that belong to each organization.

  Field	Type	Description
  id	bigint	A unique identifier for the user.
  org_id	bigint	The identifier of the organization to which the user belongs. References organizations.id.
  name	text	The user’s name.

• accounts describes the account associated with each organization.

  Field	Type	Description
  id	bigint	A unique identifier for the account.
  org_id	bigint	The identifier of the organization to which the account belongs. References organizations.id.
  balance	bigint	The balance of the account in dollars.

• auctions describes all past and ongoing auctions.

  Field	Type	Description
  id	bigint	A unique identifier for the auction.
  seller	bigint	The identifier of the user selling the item. References users.id.
  item	text	The name of the item being sold.
  end_time	timestamp with time zone	The time at which the auction closes.

• bids describes the bids placed in each auction.

  Field	Type	Description
  id	bigint	A unique identifier for the bid.
  buyer	bigint	The identifier vof the user placing the bid. References users.id.
  auction_id	bigint	The identifier of the auction in which the bid is placed. References auctions.id.
  amount	bigint	The bid amount in dollars.
  bid_time	timestamp with time zone	The time at which the bid was placed.

The organizations, users, and accounts are fixed at the time the source is created. Each tick interval, either a new auction is started, or a new bid is placed in the currently ongoing auction.

Marketing

The marketing load generator simulates a marketing organization that is using a machine learning model to send coupons to potential leads. The marketing source will be automatically demuxed into multiple subsources when the CREATE SOURCE command is executed. This will create the following subsources:

• customers describes the customers that the marketing team may target.

  Field	Type	Description
  id	bigint	A unique identifier for the customer.
  email	text	The customer’s email.
  income	bigint	The customer’s income in pennies.

• impressions describes online ads that have been seen by a customer.

  Field	Type	Description
  id	bigint	A unique identifier for the impression.
  customer_id	bigint	The identifier of the customer that saw the ad. References customers.id.
  impression_time	timestamp with time zone	The time at which the ad was seen.

• clicks describes clicks of ads.

  Field	Type	Description
  impression_id	bigint	The identifier of the impression that was clicked. References impressions.id.
  click_time	timestamp with time zone	The time at which the impression was clicked.

• leads describes a potential lead for a purchase.

  Field	Type	Description
  id	bigint	A unique identifier for the lead.
  customer_id	bigint	The identifier of the customer we’d like to convert. References customers.id.
  created_at	timestamp with time zone	The time at which the lead was created.
  converted_at	timestamp with time zone	The time at which the lead was converted.
  conversion_amount	bigint	The amount the lead converted for in pennies.

• coupons describes coupons given to leads.

  Field	Type	Description
  id	bigint	A unique identifier for the coupon.
  lead_id	bigint	The identifier of the lead we’re attempting to convert. References leads.id.
  created_at	timestamp with time zone	The time at which the coupon was created.
  amount	bigint	The amount the coupon is for in pennies.

• conversion_predictions describes the predictions made by a highly sophisticated machine learning model.

  Field	Type	Description
  lead_id	bigint	The identifier of the lead we’re attempting to convert. References leads.id.
  experiment_bucket	text	Whether the lead is a control or experiment.
  created_at	timestamp with time zone	The time at which the prediction was made.
  score	numeric	The predicted likelihood the lead will convert.

TPCH

The TPCH load generator implements the TPC-H benchmark specification. The TPCH source must be used with FOR ALL TABLES, which will create the standard TPCH relations. If TICK INTERVAL is specified, after the initial data load, an order and its lineitems will be changed at this interval. If not specified, the dataset will not change over time.

Monitoring source progress

By default, load generator sources expose progress metadata as a subsource that you can use to monitor source ingestion progress. The name of the progress subsource can be specified when creating a source using the EXPOSE PROGRESS AS clause; otherwise, it will be named <src_name>_progress.

The following metadata is available for each source as a progress subsource:

And can be queried using:

SELECT "offset"
FROM <src_name>_progress;

As long as the offset continues increasing, Materialize is generating data. For more details on monitoring source ingestion progress and debugging related issues, see Troubleshooting.

Examples

Creating a counter load generator

To create a load generator source that emits the next number in the sequence every 500 milliseconds:

CREATE SOURCE counter
  FROM LOAD GENERATOR COUNTER
  (TICK INTERVAL '500ms')
  WITH (SIZE = '3xsmall');

To examine the counter:

SELECT * FROM counter;

 counter
---------
       1
       2
       3

Creating an auction load generator

To create a load generator source that simulates an auction house and emits new data every second:

CREATE SOURCE auction_house
  FROM LOAD GENERATOR AUCTION
  (TICK INTERVAL '1s')
  FOR ALL TABLES
  WITH (SIZE = '3xsmall');

To display the created subsources:

SHOW SOURCES;

          name          |      type      |  size
------------------------+----------------+---------
 accounts               | subsource      |
 auction_house          | load-generator | 3xsmall
 auction_house_progress | progress       |
 auctions               | subsource      |
 bids                   | subsource      |
 organizations          | subsource      |
 users                  | subsource      |

To examine the simulated bids:

SELECT * from bids;

 id | buyer | auction_id | amount |          bid_time
----+-------+------------+--------+----------------------------
 10 |  3844 |          1 |     59 | 2022-09-16 23:24:07.332+00
 11 |  1861 |          1 |     40 | 2022-09-16 23:24:08.332+00
 12 |  3338 |          1 |     97 | 2022-09-16 23:24:09.332+00

Creating a marketing load generator

To create a load generator source that simulates an online marketing campaign:

CREATE SOURCE marketing
  FROM LOAD GENERATOR MARKETING
  FOR ALL TABLES
  WITH (SIZE = '3xsmall');

To display the created subsources:

SHOW SOURCES;

          name          |      type      | size
------------------------+----------------+------
 clicks                 | subsource      |
 conversion_predictions | subsource      |
 coupons                | subsource      |
 customers              | subsource      |
 impressions            | subsource      |
 leads                  | subsource      |
 marketing              | load-generator | 3xsmall
 marketing_progress     | progress       |

To find all impressions and clicks associated with a campaign over the last 30 days:

WITH
    click_rollup AS
    (
        SELECT impression_id AS id, count(*) AS clicks
        FROM clicks
        WHERE click_time - INTERVAL '30' DAY <= mz_now()
        GROUP BY impression_id
    ),
    impression_rollup AS
    (
        SELECT id, campaign_id, count(*) AS impressions
        FROM impressions
        WHERE impression_time - INTERVAL '30' DAY <= mz_now()
        GROUP BY id, campaign_id
    )
SELECT campaign_id, sum(impressions) AS impressions, sum(clicks) AS clicks
FROM impression_rollup LEFT JOIN click_rollup USING(id)
GROUP BY campaign_id;

 campaign_id | impressions | clicks
-------------+-------------+--------
           0 |         350 |     33
           1 |         325 |     28
           2 |         319 |     24
           3 |         315 |     38
           4 |         305 |     28
           5 |         354 |     31
           6 |         346 |     25
           7 |         337 |     36
           8 |         329 |     38
           9 |         305 |     24
          10 |         345 |     27
          11 |         323 |     30
          12 |         320 |     29
          13 |         331 |     27
          14 |         310 |     22
          15 |         324 |     28
          16 |         315 |     32
          17 |         329 |     36
          18 |         329 |     28

Creating a TPCH load generator

To create the load generator source and its associated subsources:

CREATE SOURCE tpch
  FROM LOAD GENERATOR TPCH (SCALE FACTOR 1)
  FOR ALL TABLES
  WITH (SIZE = '2xsmall');

To display the created subsources:

SHOW SOURCES;

      name     |      type      |  size
---------------+----------------+---------
 tpch          | load-generator | 2xsmall
 tpch_progress | progress       |
 supplier      | subsource      |
 region        | subsource      |
 partsupp      | subsource      |
 part          | subsource      |
 orders        | subsource      |
 nation        | subsource      |
 lineitem      | subsource      |
 customer      | subsource      |

To run the Pricing Summary Report Query (Q1), which reports the amount of billed, shipped, and returned items:

SELECT
    l_returnflag,
    l_linestatus,
    sum(l_quantity) AS sum_qty,
    sum(l_extendedprice) AS sum_base_price,
    sum(l_extendedprice * (1 - l_discount)) AS sum_disc_price,
    sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) AS sum_charge,
    avg(l_quantity) AS avg_qty,
    avg(l_extendedprice) AS avg_price,
    avg(l_discount) AS avg_disc,
    count(*) AS count_order
FROM
    lineitem
WHERE
    l_shipdate <= date '1998-12-01' - interval '90' day
GROUP BY
    l_returnflag,
    l_linestatus
ORDER BY
    l_returnflag,
    l_linestatus;

 l_returnflag | l_linestatus | sum_qty  | sum_base_price | sum_disc_price  |    sum_charge     |      avg_qty       |     avg_price      |      avg_disc       | count_order
--------------+--------------+----------+----------------+-----------------+-------------------+--------------------+--------------------+---------------------+-------------
 A            | F            | 37772997 |    56604341792 |  54338346989.17 |  57053313118.2657 | 25.490380624798817 | 38198.351517998075 | 0.04003729114831228 |     1481853
 N            | F            |   986796 |     1477585066 |   1418531782.89 |   1489171757.0798 | 25.463731840115603 |  38128.27564317601 | 0.04007431682708436 |       38753
 N            | O            | 74281600 |   111337230039 | 106883023012.04 | 112227399730.9018 |  25.49430183051871 | 38212.221432873834 | 0.03999775539657235 |     2913655
 R            | F            | 37770949 |    56610551077 |   54347734573.7 |  57066196254.4557 | 25.496431466814634 |  38213.68205054471 | 0.03997848687172654 |     1481421

Sizing a source

To provision a specific amount of CPU and memory to a source on creation, use the SIZE option:

CREATE SOURCE auction_load
  FROM LOAD GENERATOR AUCTION
  FOR ALL TABLES
  WITH (SIZE = '3xsmall');

To resize the source after creation:

ALTER SOURCE auction_load SET (SIZE = 'large');

The smallest source size (3xsmall) is a resonable default to get started. For more details on sizing sources, check the CREATE SOURCE documentation page.

Related pages

• CREATE SOURCE