Vertica MPP Database Overview and TPC-DS Benchmark Performance Analysis (Part 3)

March 2nd, 2018 / No Comments » / by admin

In Post 1 I outlined the key architectural principles behind Vertica’s design and what makes it one of the top MPP/analytical databases available today. In Post 2 I went over the installation process across one and multiple nodes as well as some of Vertica’s ‘knobs and buttons’ which give the administrator a comprehensive snapshot of the system performance. In this instalment I will focus on loading the data into Vertica’s cluster and running some analytical queries across TPC-DS datasets to compare execution times for single and multi-node environments. The comparison is not attempting to contrast Vertica’s performance with any of its competing MPP database vendors e.g. Greenplum or AWS Redshift (that may come in the future posts). Rather, the purpose of this post is to ascertain how queries execution are impacted based on the number of nodes in the cluster and whether the performance increases or decreases yielded were linear. Also, given that Vertica is a somewhat esoteric DBMS, I wanted to highlight the fact that with a fairly minimum set up and configuration, this MPP database can provide a lot of bang for your buck when dealing with analytical workloads. Yes, most developers or analysts would love nothing more than to jump on the cloud bandwagon and use ‘ops-free’ Google’s BigQuery or even AWS Redshift but the reality is that most SMBs are not ready to pivot their operational model and store their customers’ data in the public cloud. Databases like Vertica provide a reasonable alternative to a long established players in this market e.g. Oracle DB or IBM DB2 and allow the so-called big data demands to be addressed with relative ease i.e. multi-model deployment, full-featured SQL API, MPP architecture, in-database machine learning etc.

Cluster Setup and Data Load

There are quite a few data sets and methodologies that can be used to gauge data storage and processing system’s performance e.g. TLC Trip Record Data released by the New York City Taxi & Limousine Commission has gained a lot of traction amongst big data specialists, however,  TPC-approved benchmarks have long been considered as the most objective, vendor-agnostic way to perform data-specific hardware and software comparisons, capturing the complexity of modern business processing to a much greater extent than its predecessors. I have briefly outlined data generation mechanism used in the TPC-DS suite of tools in my previous blog HERE so I will skip the details and use three previously generated datasets for this demo – one with the scaling factor of 100 (~100GB), one with the scaling factor of 200 (~200GB) and another with the scaling factor of 300 (~300GB). All three datasets have not turned out to be perfectly uniform in terms of expected rows count (presumably due to selecting the unsupported scaling factors), with large deviations recorded across some files e.g. ‘inventory’ table containing fewer records in 200GB dataset than in the 100GB one. However, the three datasets were quite linear in terms of raw data volume increases which was also reflected in runtimes across number of subsequent queries.

As mentioned in Post 2, the hardware used for this demo is not exactly what you would have in mind when provisioning an enterprise-class database cluster. With that in mind, the results of all the analytical queries I run are only indicative of the performance level in the context of the same data and configuration used. Chances are that with a proper, server-level hardware this comparison would be like going from the Wright brothers first airplane to Starship Enterprise but at least I endeavoured to make this as empirical as possible. To be completely transparent, here is the view of how these tiny Lenovo desktops are configured.

Also, for good measure I run a quick test on the storage performance using the ‘measure_locatioon_performance’ vsql function run on one of the machines (all three nodes are identical in terms of the individual components setup). These units are equipped with an SSD each (as opposed to a slower mechanical drive), however, their SATA2 interface limits the transfer rates of what these Crucial MX300 are technically capable of to just over 360 MB/sec as per the image below.

Finally, the fact I’m pushing between 100 and 300 gigabytes of data through this cluster with only 16GB of memory available per node means that most of the data needs to be read from disk. Most analytical databases are designed to cache data in memory, providing minimal latency and fast response time. As this hardware does not do justice to the data volumes queried in this demo, with proper reference architecture for this type of system I am certain that the performance would increase by an order of magnitude.

Vertica documentation provides a detail outline of different techniques used to load, transform and monitor the acquisitions. As reiterating the details of all the options and approaches is outside the scope of this post, I will only touch on some of the core concepts – for a comprehensive guide on data loading best practices and different options available please refer to their documentation or THIS visual guide. By far, the most effective way to load the data into Vertica is using COPY command. The COPY statement loads data from a file stored on the host or client (or in a data stream) into a database table. You can pass the COPY statement many different parameters to define various options such as: the format of the incoming data, metadata about the data load, which parser COPY should use, how to transform data as it is loaded or how to handle errors. Vertica’s hybrid storage model provides a great deal of flexibility for loading and managing data.

For this demo I copied and staged the three data sets – 100GB, 200GB and 300GB – on the m92p1 host (node no1 in my makeshift 3-node cluster) and used the following shell script to (1) create necessary tables on the previously created ‘vtest’ database and ‘tpc_ds’ schema and (2) load the data into the newly created tables.

#!/bin/bash
VPASS="YourPassword"
DBNAME="vtest"
SCHEMANAME="tpc_ds"
DATAFILEPATH="/home/dbadmin/vertica_stuff/TPC_DS_Data/100GB/*.dat"
SQLFILEPATH="/home/dbadmin/vertica_stuff/TPC_DS_SQL/create_pgsql_tables.sql"

/opt/vertica/bin/vsql -f "$SQLFILEPATH" -U dbadmin -w $VPASS -d $DBNAME
for file in $DATAFILEPATH
do
    filename=$(basename "$file")
    tblname=$(basename "$file" | cut -f 1 -d '.')
    echo "Loading file "$filename" into a Vertica host..."
    #single node only:
    echo "COPY $SCHEMANAME.$tblname FROM LOCAL '/home/dbadmin/vertica_stuff/TPC_DS_Data/100GB/$filename' \
        DELIMITER '|' DIRECT;" | \
         /opt/vertica/bin/vsql \
         -U dbadmin \
         -w $VPASS \
         -d $DBNAME
done

The sql file with all the DDL statements for tables’ creation can be downloaded from my OneDrive folder HERE. The script loaded the data using DIRECT option thus straight into ROS (Read Optimised Store) to avoid engaging the Tuple Mover – database optimiser component that moves data from memory (WOS) to disk (ROS). The load times (1000 Mbps Ethernet), along with some other supporting information, for each of the three datasets are listed below.

Testing Methodology and Results

A full TPC-DS benchmark is comprised of 99 queries and governed by very specific set of rules. For brevity, this demo only includes 20 queries i.e. (query number 5, 9, 10, 13, 17, 24, 31, 33, 34, 35, 44, 46, 47, 54, 57, 64, 74, 75, 97 and 99) as a subset sample for two reasons.

  • The hardware, database setup, data volumes etc. analysed does not follow the characteristics and requirements outline by the TPC organisation and under these circumstances would be considered an ‘unacceptable consideration’. For example, a typical benchmark submitted by a vendor needs to include a number of metrics beyond query throughput e.g. a price-performance ratio, data load times, the availability date of the complete configuration etc. The following is a sample of a compliant reporting of TPC-DS results: ‘At 10GB the RALF/3000 Server has a TPC-DS Query-per-Hour metric of 3010 when run against a 10GB database yielding a TPC-DS Price/Performance of $1,202 per query-per-hour and will be available 1-Apr-06’. As this demo and the results below go only skin-deep i.e. query execution times, as previously stated, are only indicative of the performance level in the context of the same data and configuration used, enterprise-ready deployment would yield different (better) results.
  • As this post is just for fun more than science, running 20 queries seems adequate enough to gauge the performance level dichotomies between the single and the multi-cluster environments.

Also, it is worth mentioning that no performance optimisation (database or OS level) was performed on the system. Vertica allows its administrator(s) to fine-tune various aspects of its operation through mechanisms such as statistics update, table partitioning, creating query or workload-specific projections, tuning execution plans etc. Some of those techniques require a deep knowledge of Vertica’s query execution engine while others can be achieved with little effort e.g. running  DBD (Database Designer) – a GUI based tool which analyses the logical schema definition, sample data, and sample queries, and creates a physical schema in the form of a SQL script that you deploy automatically. While the initial scope of this series was intended to compare queries execution times across both versions (tuned and untuned), given the fact that Vertica’s is purposefully suited to run on a cluster of hosts, I decided to focus on contrasting single vs multi-node cluster deployment instead. Therefore, the results are only indicative of the performance level in the context of the same data and configuration used, with a good chance that further tuning, tweaking or other optimisation techniques would have yielded a much better performance outcomes.

OK, now with this little declaimer out of the way let’s look at how the first ten queries performed across the two distinct setups i.e. single node cluster and multi-node (3 nodes) cluster. Additional queries’ results as well as a quick look at a Tableau and PowerBI performance please refer to Part 4 of this series.

--Query 5
WITH ssr AS
(
         SELECT   s_store_id,
                  Sum(sales_price) AS sales,
                  Sum(profit)      AS profit,
                  Sum(return_amt)  AS returns1,
                  Sum(net_loss)    AS profit_loss
         FROM     (
                         SELECT ss_store_sk             AS store_sk,
                                ss_sold_date_sk         AS date_sk,
                                ss_ext_sales_price      AS sales_price,
                                ss_net_profit           AS profit,
                                Cast(0 AS DECIMAL(7,2)) AS return_amt,
                                Cast(0 AS DECIMAL(7,2)) AS net_loss
                         FROM   tpc_ds.store_sales
                         UNION ALL
                         SELECT sr_store_sk             AS store_sk,
                                sr_returned_date_sk     AS date_sk,
                                Cast(0 AS DECIMAL(7,2)) AS sales_price,
                                Cast(0 AS DECIMAL(7,2)) AS profit,
                                sr_return_amt           AS return_amt,
                                sr_net_loss             AS net_loss
                         FROM   tpc_ds.store_returns ) salesreturns,
                  tpc_ds.date_dim,
                  tpc_ds.store
         WHERE    date_sk = d_date_sk
         AND      d_date BETWEEN Cast('2002-08-22' AS DATE) AND      (
                           Cast('2002-08-22' AS DATE) + INTERVAL '14' day)
         AND      store_sk = s_store_sk
         GROUP BY s_store_id) , csr AS
(
         SELECT   cp_catalog_page_id,
                  sum(sales_price) AS sales,
                  sum(profit)      AS profit,
                  sum(return_amt)  AS returns1,
                  sum(net_loss)    AS profit_loss
         FROM     (
                         SELECT cs_catalog_page_sk      AS page_sk,
                                cs_sold_date_sk         AS date_sk,
                                cs_ext_sales_price      AS sales_price,
                                cs_net_profit           AS profit,
                                cast(0 AS decimal(7,2)) AS return_amt,
                                cast(0 AS decimal(7,2)) AS net_loss
                         FROM   tpc_ds.catalog_sales
                         UNION ALL
                         SELECT cr_catalog_page_sk      AS page_sk,
                                cr_returned_date_sk     AS date_sk,
                                cast(0 AS decimal(7,2)) AS sales_price,
                                cast(0 AS decimal(7,2)) AS profit,
                                cr_return_amount        AS return_amt,
                                cr_net_loss             AS net_loss
                         FROM   tpc_ds.catalog_returns ) salesreturns,
                  tpc_ds.date_dim,
                  tpc_ds.catalog_page
         WHERE    date_sk = d_date_sk
         AND      d_date BETWEEN cast('2002-08-22' AS date) AND      (
                           cast('2002-08-22' AS date) + INTERVAL '14' day)
         AND      page_sk = cp_catalog_page_sk
         GROUP BY cp_catalog_page_id) , wsr AS
(
         SELECT   web_site_id,
                  sum(sales_price) AS sales,
                  sum(profit)      AS profit,
                  sum(return_amt)  AS returns1,
                  sum(net_loss)    AS profit_loss
         FROM     (
                         SELECT ws_web_site_sk          AS wsr_web_site_sk,
                                ws_sold_date_sk         AS date_sk,
                                ws_ext_sales_price      AS sales_price,
                                ws_net_profit           AS profit,
                                cast(0 AS decimal(7,2)) AS return_amt,
                                cast(0 AS decimal(7,2)) AS net_loss
                         FROM   tpc_ds.web_sales
                         UNION ALL
                         SELECT          ws_web_site_sk          AS wsr_web_site_sk,
                                         wr_returned_date_sk     AS date_sk,
                                         cast(0 AS decimal(7,2)) AS sales_price,
                                         cast(0 AS decimal(7,2)) AS profit,
                                         wr_return_amt           AS return_amt,
                                         wr_net_loss             AS net_loss
                         FROM            tpc_ds.web_returns
                         LEFT OUTER JOIN tpc_ds.web_sales
                         ON              (
                                                         wr_item_sk = ws_item_sk
                                         AND             wr_order_number = ws_order_number) ) salesreturns,
                  tpc_ds.date_dim,
                  tpc_ds.web_site
         WHERE    date_sk = d_date_sk
         AND      d_date BETWEEN cast('2002-08-22' AS date) AND      (
                           cast('2002-08-22' AS date) + INTERVAL '14' day)
         AND      wsr_web_site_sk = web_site_sk
         GROUP BY web_site_id)
SELECT
         channel ,
         id ,
         sum(sales)   AS sales ,
         sum(returns1) AS returns1 ,
         sum(profit)  AS profit
FROM     (
                SELECT 'store channel' AS channel ,
                       'store'
                              || s_store_id AS id ,
                       sales ,
                       returns1 ,
                       (profit - profit_loss) AS profit
                FROM   ssr
                UNION ALL
                SELECT 'catalog channel' AS channel ,
                       'catalog_page'
                              || cp_catalog_page_id AS id ,
                       sales ,
                       returns1 ,
                       (profit - profit_loss) AS profit
                FROM   csr
                UNION ALL
                SELECT 'web channel' AS channel ,
                       'web_site'
                              || web_site_id AS id ,
                       sales ,
                       returns1 ,
                       (profit - profit_loss) AS profit
                FROM   wsr ) x
GROUP BY rollup (channel, id)
ORDER BY channel ,
         id
LIMIT 100;

--Query 9
SELECT CASE
         WHEN (SELECT Count(*)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 1 AND 20) > 3672 THEN
         (SELECT Avg(ss_ext_list_price)
          FROM   tpc_ds.store_sales
          WHERE
         ss_quantity BETWEEN 1 AND 20)
         ELSE (SELECT Avg(ss_net_profit)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 1 AND 20)
       END bucket1,
       CASE
         WHEN (SELECT Count(*)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 21 AND 40) > 3392 THEN
         (SELECT Avg(ss_ext_list_price)
          FROM   tpc_ds.store_sales
          WHERE
         ss_quantity BETWEEN 21 AND 40)
         ELSE (SELECT Avg(ss_net_profit)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 21 AND 40)
       END bucket2,
       CASE
         WHEN (SELECT Count(*)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 41 AND 60) > 32784 THEN
         (SELECT Avg(ss_ext_list_price)
          FROM   tpc_ds.store_sales
          WHERE
         ss_quantity BETWEEN 41 AND 60)
         ELSE (SELECT Avg(ss_net_profit)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 41 AND 60)
       END bucket3,
       CASE
         WHEN (SELECT Count(*)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 61 AND 80) > 26032 THEN
         (SELECT Avg(ss_ext_list_price)
          FROM   tpc_ds.store_sales
          WHERE
         ss_quantity BETWEEN 61 AND 80)
         ELSE (SELECT Avg(ss_net_profit)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 61 AND 80)
       END bucket4,
       CASE
         WHEN (SELECT Count(*)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 81 AND 100) > 23982 THEN
         (SELECT Avg(ss_ext_list_price)
          FROM   tpc_ds.store_sales
          WHERE
         ss_quantity BETWEEN 81 AND 100)
         ELSE (SELECT Avg(ss_net_profit)
               FROM   tpc_ds.store_sales
               WHERE  ss_quantity BETWEEN 81 AND 100)
       END bucket5
FROM   tpc_ds.reason
WHERE  r_reason_sk = 1;

--Query 10
SELECT cd_gender,
               cd_marital_status,
               cd_education_status,
               Count(*) cnt1,
               cd_purchase_estimate,
               Count(*) cnt2,
               cd_credit_rating,
               Count(*) cnt3,
               cd_dep_count,
               Count(*) cnt4,
               cd_dep_employed_count,
               Count(*) cnt5,
               cd_dep_college_count,
               Count(*) cnt6
FROM   tpc_ds.customer c,
       tpc_ds.customer_address ca,
       tpc_ds.customer_demographics
WHERE  c.c_current_addr_sk = ca.ca_address_sk
       AND ca_county IN ( 'Lycoming County', 'Sheridan County',
                          'Kandiyohi County',
                          'Pike County',
                                           'Greene County' )
       AND cd_demo_sk = c.c_current_cdemo_sk
       AND EXISTS (SELECT *
                   FROM   tpc_ds.store_sales,
                          tpc_ds.date_dim
                   WHERE  c.c_customer_sk = ss_customer_sk
                          AND ss_sold_date_sk = d_date_sk
                          AND d_year = 2002
                          AND d_moy BETWEEN 4 AND 4 + 3)
       AND ( EXISTS (SELECT *
                     FROM   tpc_ds.web_sales,
                            tpc_ds.date_dim
                     WHERE  c.c_customer_sk = ws_bill_customer_sk
                            AND ws_sold_date_sk = d_date_sk
                            AND d_year = 2002
                            AND d_moy BETWEEN 4 AND 4 + 3)
              OR EXISTS (SELECT *
                         FROM   tpc_ds.catalog_sales,
                                tpc_ds.date_dim
                         WHERE  c.c_customer_sk = cs_ship_customer_sk
                                AND cs_sold_date_sk = d_date_sk
                                AND d_year = 2002
                                AND d_moy BETWEEN 4 AND 4 + 3) )
GROUP  BY cd_gender,
          cd_marital_status,
          cd_education_status,
          cd_purchase_estimate,
          cd_credit_rating,
          cd_dep_count,
          cd_dep_employed_count,
          cd_dep_college_count
ORDER  BY cd_gender,
          cd_marital_status,
          cd_education_status,
          cd_purchase_estimate,
          cd_credit_rating,
          cd_dep_count,
          cd_dep_employed_count,
          cd_dep_college_count
LIMIT 100;

--Query 13
SELECT Avg(ss_quantity),
       Avg(ss_ext_sales_price),
       Avg(ss_ext_wholesale_cost),
       Sum(ss_ext_wholesale_cost)
FROM   tpc_ds.store_sales,
       tpc_ds.store,
       tpc_ds.customer_demographics,
       tpc_ds.household_demographics,
       tpc_ds.customer_address,
       tpc_ds.date_dim
WHERE  s_store_sk = ss_store_sk
       AND ss_sold_date_sk = d_date_sk
       AND d_year = 2001
       AND ( ( ss_hdemo_sk = hd_demo_sk
               AND cd_demo_sk = ss_cdemo_sk
               AND cd_marital_status = 'U'
               AND cd_education_status = 'Advanced Degree'
               AND ss_sales_price BETWEEN 100.00 AND 150.00
               AND hd_dep_count = 3 )
              OR ( ss_hdemo_sk = hd_demo_sk
                   AND cd_demo_sk = ss_cdemo_sk
                   AND cd_marital_status = 'M'
                   AND cd_education_status = 'Primary'
                   AND ss_sales_price BETWEEN 50.00 AND 100.00
                   AND hd_dep_count = 1 )
              OR ( ss_hdemo_sk = hd_demo_sk
                   AND cd_demo_sk = ss_cdemo_sk
                   AND cd_marital_status = 'D'
                   AND cd_education_status = 'Secondary'
                   AND ss_sales_price BETWEEN 150.00 AND 200.00
                   AND hd_dep_count = 1 ) )
       AND ( ( ss_addr_sk = ca_address_sk
               AND ca_country = 'United States'
               AND ca_state IN ( 'AZ', 'NE', 'IA' )
               AND ss_net_profit BETWEEN 100 AND 200 )
              OR ( ss_addr_sk = ca_address_sk
                   AND ca_country = 'United States'
                   AND ca_state IN ( 'MS', 'CA', 'NV' )
                   AND ss_net_profit BETWEEN 150 AND 300 )
              OR ( ss_addr_sk = ca_address_sk
                   AND ca_country = 'United States'
                   AND ca_state IN ( 'GA', 'TX', 'NJ' )
                   AND ss_net_profit BETWEEN 50 AND 250 ) );

--Query 17
SELECT i_item_id,
               i_item_desc,
               s_state,
               Count(ss_quantity)                                        AS
               store_sales_quantitycount,
               Avg(ss_quantity)                                          AS
               store_sales_quantityave,
               Stddev_samp(ss_quantity)                                  AS
               store_sales_quantitystdev,
               Stddev_samp(ss_quantity) / Avg(ss_quantity)               AS
               store_sales_quantitycov,
               Count(sr_return_quantity)                                 AS
               store_returns_quantitycount,
               Avg(sr_return_quantity)                                   AS
               store_returns_quantityave,
               Stddev_samp(sr_return_quantity)                           AS
               store_returns_quantitystdev,
               Stddev_samp(sr_return_quantity) / Avg(sr_return_quantity) AS
               store_returns_quantitycov,
               Count(cs_quantity)                                        AS
               catalog_sales_quantitycount,
               Avg(cs_quantity)                                          AS
               catalog_sales_quantityave,
               Stddev_samp(cs_quantity) / Avg(cs_quantity)               AS
               catalog_sales_quantitystdev,
               Stddev_samp(cs_quantity) / Avg(cs_quantity)               AS
               catalog_sales_quantitycov
FROM   tpc_ds.store_sales,
       tpc_ds.store_returns,
       tpc_ds.catalog_sales,
       tpc_ds.date_dim d1,
       tpc_ds.date_dim d2,
       tpc_ds.date_dim d3,
       tpc_ds.store,
       tpc_ds.item
WHERE  d1.d_quarter_name = '1999Q1'
       AND d1.d_date_sk = ss_sold_date_sk
       AND i_item_sk = ss_item_sk
       AND s_store_sk = ss_store_sk
       AND ss_customer_sk = sr_customer_sk
       AND ss_item_sk = sr_item_sk
       AND ss_ticket_number = sr_ticket_number
       AND sr_returned_date_sk = d2.d_date_sk
       AND d2.d_quarter_name IN ( '1999Q1', '1999Q2', '1999Q3' )
       AND sr_customer_sk = cs_bill_customer_sk
       AND sr_item_sk = cs_item_sk
       AND cs_sold_date_sk = d3.d_date_sk
       AND d3.d_quarter_name IN ( '1999Q1', '1999Q2', '1999Q3' )
GROUP  BY i_item_id,
          i_item_desc,
          s_state
ORDER  BY i_item_id,
          i_item_desc,
          s_state
LIMIT 100;

--Query 24
WITH ssales 
     AS (SELECT c_last_name, 
                c_first_name, 
                s_store_name, 
                ca_state, 
                s_state, 
                i_color, 
                i_current_price, 
                i_manager_id, 
                i_units, 
                i_size, 
                Sum(ss_net_profit) netpaid 
         FROM   tpc_ds.store_sales,
                tpc_ds.store_returns,
                tpc_ds.store,
                tpc_ds.item,
                tpc_ds.customer,
                tpc_ds.customer_address
         WHERE  ss_ticket_number = sr_ticket_number 
                AND ss_item_sk = sr_item_sk 
                AND ss_customer_sk = c_customer_sk 
                AND ss_item_sk = i_item_sk 
                AND ss_store_sk = s_store_sk 
                AND c_birth_country = Upper(ca_country) 
                AND s_zip = ca_zip 
                AND s_market_id = 6 
         GROUP  BY c_last_name, 
                   c_first_name, 
                   s_store_name, 
                   ca_state, 
                   s_state, 
                   i_color, 
                   i_current_price, 
                   i_manager_id, 
                   i_units, 
                   i_size) 
SELECT c_last_name, 
       c_first_name, 
       s_store_name, 
       Sum(netpaid) paid 
FROM   ssales 
WHERE  i_color = 'papaya' 
GROUP  BY c_last_name, 
          c_first_name, 
          s_store_name 
HAVING Sum(netpaid) > (SELECT 0.05 * Avg(netpaid) 
                       FROM   ssales); 

WITH ssales 
     AS (SELECT c_last_name, 
                c_first_name, 
                s_store_name, 
                ca_state, 
                s_state, 
                i_color, 
                i_current_price, 
                i_manager_id, 
                i_units, 
                i_size, 
                Sum(ss_net_profit) netpaid 
         FROM   tpc_ds.store_sales,
                tpc_ds.store_returns,
                tpc_ds.store,
                tpc_ds.item,
                tpc_ds.customer,
                tpc_ds.customer_address
         WHERE  ss_ticket_number = sr_ticket_number 
                AND ss_item_sk = sr_item_sk 
                AND ss_customer_sk = c_customer_sk 
                AND ss_item_sk = i_item_sk 
                AND ss_store_sk = s_store_sk 
                AND c_birth_country = Upper(ca_country) 
                AND s_zip = ca_zip 
                AND s_market_id = 6 
         GROUP  BY c_last_name, 
                   c_first_name, 
                   s_store_name, 
                   ca_state, 
                   s_state, 
                   i_color, 
                   i_current_price, 
                   i_manager_id, 
                   i_units, 
                   i_size) 
SELECT c_last_name, 
       c_first_name, 
       s_store_name, 
       Sum(netpaid) paid 
FROM   ssales 
WHERE  i_color = 'chartreuse' 
GROUP  BY c_last_name, 
          c_first_name, 
          s_store_name 
HAVING Sum(netpaid) > (SELECT 0.05 * Avg(netpaid) 
                       FROM   ssales); 

--Query 31
WITH ss
     AS (SELECT ca_county,
                d_qoy,
                d_year,
                Sum(ss_ext_sales_price) AS store_sales
         FROM   tpc_ds.store_sales,
                tpc_ds.date_dim,
                tpc_ds.customer_address
         WHERE  ss_sold_date_sk = d_date_sk
                AND ss_addr_sk = ca_address_sk
         GROUP  BY ca_county,
                   d_qoy,
                   d_year),
     ws
     AS (SELECT ca_county,
                d_qoy,
                d_year,
                Sum(ws_ext_sales_price) AS web_sales
         FROM   tpc_ds.web_sales,
                tpc_ds.date_dim,
                tpc_ds.customer_address
         WHERE  ws_sold_date_sk = d_date_sk
                AND ws_bill_addr_sk = ca_address_sk
         GROUP  BY ca_county,
                   d_qoy,
                   d_year)
SELECT ss1.ca_county,
       ss1.d_year,
       ws2.web_sales / ws1.web_sales     web_q1_q2_increase,
       ss2.store_sales / ss1.store_sales store_q1_q2_increase,
       ws3.web_sales / ws2.web_sales     web_q2_q3_increase,
       ss3.store_sales / ss2.store_sales store_q2_q3_increase
FROM   ss ss1,
       ss ss2,
       ss ss3,
       ws ws1,
       ws ws2,
       ws ws3
WHERE  ss1.d_qoy = 1
       AND ss1.d_year = 2001
       AND ss1.ca_county = ss2.ca_county
       AND ss2.d_qoy = 2
       AND ss2.d_year = 2001
       AND ss2.ca_county = ss3.ca_county
       AND ss3.d_qoy = 3
       AND ss3.d_year = 2001
       AND ss1.ca_county = ws1.ca_county
       AND ws1.d_qoy = 1
       AND ws1.d_year = 2001
       AND ws1.ca_county = ws2.ca_county
       AND ws2.d_qoy = 2
       AND ws2.d_year = 2001
       AND ws1.ca_county = ws3.ca_county
       AND ws3.d_qoy = 3
       AND ws3.d_year = 2001
       AND CASE
             WHEN ws1.web_sales > 0 THEN ws2.web_sales / ws1.web_sales
             ELSE NULL
           END > CASE
                   WHEN ss1.store_sales > 0 THEN
                   ss2.store_sales / ss1.store_sales
                   ELSE NULL
                 END
       AND CASE
             WHEN ws2.web_sales > 0 THEN ws3.web_sales / ws2.web_sales
             ELSE NULL
           END > CASE
                   WHEN ss2.store_sales > 0 THEN
                   ss3.store_sales / ss2.store_sales
                   ELSE NULL
                 END
ORDER  BY ss1.d_year;	

--Query 33
WITH ss
     AS (SELECT i_manufact_id,
                Sum(ss_ext_sales_price) total_sales
         FROM   tpc_ds.store_sales,
                tpc_ds.date_dim,
                tpc_ds.customer_address,
                tpc_ds.item
         WHERE  i_manufact_id IN (SELECT i_manufact_id
                                  FROM   tpc_ds.item
                                  WHERE  i_category IN ( 'Books' ))
                AND ss_item_sk = i_item_sk
                AND ss_sold_date_sk = d_date_sk
                AND d_year = 1999
                AND d_moy = 3
                AND ss_addr_sk = ca_address_sk
                AND ca_gmt_offset = -5
         GROUP  BY i_manufact_id),
     cs
     AS (SELECT i_manufact_id,
                Sum(cs_ext_sales_price) total_sales
         FROM   tpc_ds.catalog_sales,
                tpc_ds.date_dim,
                tpc_ds.customer_address,
                tpc_ds.item
         WHERE  i_manufact_id IN (SELECT i_manufact_id
                                  FROM   tpc_ds.item
                                  WHERE  i_category IN ( 'Books' ))
                AND cs_item_sk = i_item_sk
                AND cs_sold_date_sk = d_date_sk
                AND d_year = 1999
                AND d_moy = 3
                AND cs_bill_addr_sk = ca_address_sk
                AND ca_gmt_offset = -5
         GROUP  BY i_manufact_id),
     ws
     AS (SELECT i_manufact_id,
                Sum(ws_ext_sales_price) total_sales
         FROM   tpc_ds.web_sales,
                tpc_ds.date_dim,
                tpc_ds.customer_address,
                tpc_ds.item
         WHERE  i_manufact_id IN (SELECT i_manufact_id
                                  FROM   tpc_ds.item
                                  WHERE  i_category IN ( 'Books' ))
                AND ws_item_sk = i_item_sk
                AND ws_sold_date_sk = d_date_sk
                AND d_year = 1999
                AND d_moy = 3
                AND ws_bill_addr_sk = ca_address_sk
                AND ca_gmt_offset = -5
         GROUP  BY i_manufact_id)
SELECT i_manufact_id,
               Sum(total_sales) total_sales
FROM   (SELECT *
        FROM   ss
        UNION ALL
        SELECT *
        FROM   cs
        UNION ALL
        SELECT *
        FROM   ws) tmp1
GROUP  BY i_manufact_id
ORDER  BY total_sales
LIMIT 100;

--Query 34
SELECT c_last_name, 
       c_first_name, 
       c_salutation, 
       c_preferred_cust_flag, 
       ss_ticket_number, 
       cnt 
FROM   (SELECT ss_ticket_number, 
               ss_customer_sk, 
               Count(*) cnt 
        FROM   tpc_ds.store_sales,
               tpc_ds.date_dim,
               tpc_ds.store,
               tpc_ds.household_demographics
        WHERE  store_sales.ss_sold_date_sk = date_dim.d_date_sk 
               AND store_sales.ss_store_sk = store.s_store_sk 
               AND store_sales.ss_hdemo_sk = household_demographics.hd_demo_sk 
               AND ( date_dim.d_dom BETWEEN 1 AND 3 
                      OR date_dim.d_dom BETWEEN 25 AND 28 ) 
               AND ( household_demographics.hd_buy_potential = '>10000' 
                      OR household_demographics.hd_buy_potential = 'unknown' ) 
               AND household_demographics.hd_vehicle_count > 0 
               AND ( CASE 
                       WHEN household_demographics.hd_vehicle_count > 0 THEN 
                       household_demographics.hd_dep_count / 
                       household_demographics.hd_vehicle_count 
                       ELSE NULL 
                     END ) > 1.2 
               AND date_dim.d_year IN ( 1999, 1999 + 1, 1999 + 2 ) 
               AND store.s_county IN ( 'Williamson County', 'Williamson County', 
                                       'Williamson County', 
                                                             'Williamson County' 
                                       , 
                                       'Williamson County', 'Williamson County', 
                                           'Williamson County', 
                                                             'Williamson County' 
                                     ) 
        GROUP  BY ss_ticket_number, 
                  ss_customer_sk) dn, 
       tpc_ds.customer
WHERE  ss_customer_sk = c_customer_sk 
       AND cnt BETWEEN 15 AND 20 
ORDER  BY c_last_name, 
          c_first_name, 
          c_salutation, 
          c_preferred_cust_flag DESC; 

--Query 35
SELECT ca_state,
               cd_gender,
               cd_marital_status,
               cd_dep_count,
               Count(*) cnt1,
               Stddev_samp(cd_dep_count),
               Avg(cd_dep_count),
               Max(cd_dep_count),
               cd_dep_employed_count,
               Count(*) cnt2,
               Stddev_samp(cd_dep_employed_count),
               Avg(cd_dep_employed_count),
               Max(cd_dep_employed_count),
               cd_dep_college_count,
               Count(*) cnt3,
               Stddev_samp(cd_dep_college_count),
               Avg(cd_dep_college_count),
               Max(cd_dep_college_count)
FROM   tpc_ds.customer c,
       tpc_ds.customer_address ca,
       tpc_ds.customer_demographics
WHERE  c.c_current_addr_sk = ca.ca_address_sk
       AND cd_demo_sk = c.c_current_cdemo_sk
       AND EXISTS (SELECT *
                   FROM   tpc_ds.store_sales,
                          tpc_ds.date_dim
                   WHERE  c.c_customer_sk = ss_customer_sk
                          AND ss_sold_date_sk = d_date_sk
                          AND d_year = 2001
                          AND d_qoy < 4)
       AND ( EXISTS (SELECT *
                     FROM   tpc_ds.web_sales,
                            tpc_ds.date_dim
                     WHERE  c.c_customer_sk = ws_bill_customer_sk
                            AND ws_sold_date_sk = d_date_sk
                            AND d_year = 2001
                            AND d_qoy < 4)
              OR EXISTS (SELECT *
                         FROM   tpc_ds.catalog_sales,
                                tpc_ds.date_dim
                         WHERE  c.c_customer_sk = cs_ship_customer_sk
                                AND cs_sold_date_sk = d_date_sk
                                AND d_year = 2001
                                AND d_qoy < 4) )
GROUP  BY ca_state,
          cd_gender,
          cd_marital_status,
          cd_dep_count,
          cd_dep_employed_count,
          cd_dep_college_count
ORDER  BY ca_state,
          cd_gender,
          cd_marital_status,
          cd_dep_count,
          cd_dep_employed_count,
          cd_dep_college_count
LIMIT 100;		

I decided to break up the queries’ performance analysis into two parts. Further TPC-DS queries’ results, along with a quick look at how Vertica plays with Tableau and PowerBI applications, can be viewed in Part 4 to this series but we can already see the execution pattern and how data volumes and its distribution across multiple nodes impact the performance. Again, please refer to Post 4 for data on the additional ten queries performance results and my final comments on this experiment.

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Vertica MPP Database Overview and TPC-DS Benchmark Performance Analysis (Part 2)

February 1st, 2018 / 1 Comment » / by admin

In Post 1 I outlined the key architectural principles behind Vertica’s design and what makes it one of the top MPP/analytical databases available today. In this instalment, I will go through the database installation process (across one and multiple nodes), some of the issues I encountered (specific to the off-the-shelf hardware I used) as well as some other titbits regarding subsequent configuration and tuning. For a TLDR version of Vertica installation process you can watch the following video instead.

Vertica can be installed on any compatible x86 architecture hardware so for the purpose of this demo I decided dust off a few of my old and trusty Lenovo m92p units. Even though these machines are typically used in an office/home to run desktop applications, not in a data centre environment to run database intensive workloads, for the purpose of this demo they should provide a good testing platform for evaluation and kicking Vertica’s tires. Heck, if Greenplum is proud to run their MPP database on a cluster of Raspberries Pi (check out the video HERE), why not run Vertica on a stack of low-powered Lenovo desktops running Ubuntu Server. Below is a photo of the actual machines running Vertica version 9.1 fitted with Intel Core i5 3470 CPU, 16GB of DDR3 memory and 512GB of Crucial MX300 SSD in each of the three computers (bottom three units).

Installing Vertica

Before installing Vertica, the following key points should be taken into consideration.

  • Only one database instance can run per cluster. So, if we were to provision a three-node cluster, then all three nodes will be dedicated to one single database.
  • Only one instance of Vertica is allowed to run on a host at any time.
  • Only the root user or the user with the privileges (sudo) can run the install_vertica script.

Vertica installation process also imposes some rigid requirements around swap space available, dynamic CPU scaling, network configuration and disk space and memory requirements. As these are quite comprehensive in terms of actual Linux side configuration I won’t go into details on how these requirements and their parameters need to be tuned and adjusted (beyond the issues I encountered and the fixes I performed) as Vertica’s documentation available on their website outlines all these options in great details.

Below is a step by step overview of how to install Vertica (single node configuration) on Ubuntu Server 14.04 LTS with some of the problems encountered and the fixes implemented to rectify them. I will also provide details on how to add nodes to existing installation towards the end of this post.

To install Vertica as a single node cluster the following steps will be applied:

  • Download the Vertica installation package from the vendor’s website according to the Linux OS applicable to your environment. In my case, I used Ubuntu Server 14.04 LTS release so majority of the steps below apply to this particular Linux distribution.
  • Disable firewall.
    sudo ufw disable 
    
  • Install supporting packages.
    #required for interactivity with Administration Tools
    apt-get install dialog 
    #required for Administration Tools connectivity between nodes
    apt-get install openssh
    
  • Install the downloaded package using standard comma
    sudo dpkg -i /pathname/vertica_x.x.x.x.x.deb
    
  • Install Vertica by running the install_vertica script with the required parameters supplied.
    /opt/vertica/sbin/install_vertica --hosts node0001,node0002,node0003\
    --deb /tmp/vertica_9.0.x.x86_64.deb 
    --dba-user dbadmin
    

    In my case the initiated installation failed reporting the following errors (last three FAIL statements).

    First issue related to the system reporting invalid CPU scaling. The installer allows CPU frequency scaling to be enabled when cpufreq scaling governor is set to performance. If the CPU scaling governor is set to on-demand, and ignore_nice_load is 1 (true), then the installer fails with the error S0140. CPU scaling is a hardware and software feature that helps computers conserver energy by slowing the processor when the system load is low, and speeding it up again when the system load increases. Typically, you disable the CPU scaling in the hosts’s BIOS but as it was the case with my machine, the settings tweaking did nothing to discourage Vertica installer from throwing the error presumably due to the fact I was running the T version of Intel CPU i.e. ‘Power-optimised lifestyle’. The next best thing to do was to tweak it through the Linux kernel or setting the CPU frequency governor to always run the CPU at full speed.

    This can be fixed by installing cpufrequtils package and manually changing the CPU governor’s settings.

    apt-get install cpufrequtils
    sudo cpufreq-set -c 0 -g performance
    sudo cpufreq-set -c 1 -g performance
    sudo cpufreq-set -c 2 -g performance
    sudo cpufreq-set -c 3 -g performance
    

    Next, the installer raised an issue with the ntp deamon not running. The network time protocol (NTP) deamon must be running on all of the nodes in the cluster so that their clocks are synchronised for timing purposes. By default, the NPT deamon is not installed on some Ubuntu and Debian systems. First, let’s install it and start the NTP process.

    sudo apt-get install ntp
    sudo /etc/init.d/ntp reload
    

    To verify the the Network Time Protocol deamon is operating correctly we can issue the following command on all nodes in the cluster.

    ntpq -c rv | grep stratum
    

    A stratum level of 16 indicates that NTP is not synchronising correctly. If a stratum level of 16 is detected, wait 15 minutes and issue the command again. If NTP continues to detect a stratum level of 16, verify that the NTP port (UDP Port 123) is open on all firewalls between the cluster and the remote machine to which you are attempting to synchronise.

    Finally, the installer also complained that ‘the transparent hugepages is set to always and that it must be set to never or madvise. This can be ractified by editing the boot loader (for example /etc/grub.conf) or editing /etc/rc.local (on a system that supports rc.local) and adding the following script.

    if test -f /sys/kernel/mm/transparent_hugepages/enabled; then
    echo never > /sys/kernel/mm/transparent_hugepages/enabled
    fi
    

    Regardless of the approach, you must reboot your system for the settings to take effect, or run the following to echo lines to proceed with the install without rebooting.

    sudo su
    echo never > /sys/kernel/mm/transparent_hugepage/enabled
    

    Next, when trying to run the installation script again, another issue (this time a warning) about swappiness came up as per the image below.

    The swappiness kernel parameter defines the amount, and how often, the kernel copies RAM contents to a swap space. Vertica recommends a value of 1. To fix this issue we can run the following command to alter the parameter value.

    echo 1 > /proc/sys/vm/swappiness
    

    Fortunately, after rectifying the swappiness issue rest of the installation went trouble-free.

  • After we have installed Vertica on all desired nodes, it’s time to create a database. Log in as a new user (dbadmin in default scenarios) and connect to the admin panel by running the followinmand.
    /opt/vertica/bin/adminTools
    
  • If you are connecting to admin tools for the first time, you will be prompted for a license key. Since we’re using the community edition we will just leave it blank and click OK.
  • After accepting EULA we can navigate to Administration Tools | Configuration Menu | Create Database menu and provide the database name and password.
  • Once the database is created we can connect to it using VSQL tool to perform admin tasks. Vertica also allows administrators to invoke most Administration Tools from the command line or a shell script. We can list all available tools and their commands and options in individual help text as per below.
    $ admintools -a
    Usage:
        adminTools [-t | --tool] toolName [options]
    Valid tools are:
                    command_host
                    connect_db
                    create_db
                    database_parameters
                    db_add_node
                    db_remove_node
                    db_replace_node
                    db_status
                    distribute_config_files
                    drop_db
                    host_to_node
                    install_package
                    install_procedure
                    kill_host
                    kill_node
                    license_audit
                    list_allnodes
                    list_db
                    list_host
                    list_node
                    list_packages
                    logrotate
                    node_map
                    re_ip
                    rebalance_data
                    restart_db
                    restart_node
                    return_epoch
                    revive_db
                    set_restart_policy
                    set_ssl_params
                    show_active_db
                    start_db
                    stop_db
                    stop_host
                    stop_node
                    uninstall_package
                    upgrade_license_key
                    view_cluster
    

    Each tool comes with its own parameters. For example, the following three examples display the command option for command_host, connect_db and create_db tools.

    Usage: command_host [options]
    
    Options:
      -h, --help            show this help message and exit
      -c CMD, --command=CMD
                            Command to run
    -------------------------------------------------------------------------
    Usage: connect_db [options]
    
    Options:
      -h, --help            show this help message and exit
      -d DB, --database=DB  Name of database to connect
      -p DBPASSWORD, --password=DBPASSWORD
                            Database password in single quotes
    -------------------------------------------------------------------------
    Usage: create_db [options]
    
    Options:
      -h, --help            show this help message and exit
      -D DATA, --data_path=DATA
                            Path of data directory[optional] if not using compat21
      -c CATALOG, --catalog_path=CATALOG
                            Path of catalog directory[optional] if not using
                            compat21
      --compat21            (deprecated) Use Vertica 2.1 method using node names
                            instead of hostnames
      -d DB, --database=DB  Name of database to be created
      -l LICENSEFILE, --license=LICENSEFILE
                            Database license [optional]
      -p DBPASSWORD, --password=DBPASSWORD
                            Database password in single quotes [optional]
      -P POLICY, --policy=POLICY
                            Database restart policy [optional]
      -s NODES, --hosts=NODES
                            comma-separated list of hosts to participate in
                            database
      --skip-fs-checks      Skip file system checks while creating a database (not
                            recommended).
    

The Management Console provides some, but not all, of the functionality that the Administration Tools provides. In addition, the MC provides extended functionality not available in the Administration Tools, such as a graphical view of your Vertica database and detailed monitoring charts and graphs.

To install MC download the MC package from myVertica portal and save it to a location on the target server, such as /tmp. On the target server, log in as root or a user with sudo privileges, change directory to the location where you saved the MC package and install MC using your local Linux distribution package management system (for example, rpm, yum, zipper, apt, dpkg). In my case, since I run Ubuntu Server that will look like the following.

sudo dpkg -i vertica-console-<current-version>.deb

Next, open a browser and enter the IP address or host name of the server on which you installed MC, as well as the default MC port 5450. For example, you’ll enter one of the following.

https://xx.xx.xx.xx:5450/ 
https://hostname:5450/

When the Configuration Wizard dialog box appears, proceed to Configuring Management Console.

Vertica being a distributed database stores and retrieves data from multiple nodes in a typical setup. There are many reasons for adding one or more nodes to an installation of Vertica e.g. make a database K-safe, swapping nodes for maintenance or replacing/removing a node due to, for example, a malfunctioning hardware. To add a new node, we can use the update_vertica script. However, before adding a node to an existing cluster, the following prerequisites have to be kept in mind.

  • Make sure that the database is running.
  • Newly added node should be reachable by all existing nodes in the cluster.
  • Generally, it is not needed to shut down the Vertica database for expansion, but a shutdown is necessary if we are expending it from a single node cluster.

Adding a new node is as simple as running the after mentioned update_vertica script e.g.

/opt/vertica/sbin/update_vetica --add-hosts host(s) -deb package

The update_vertica script uses all the same options as install_vertica script and beyond Vertica installation it performs post-installation checks, modifies spread to encompass the larger cluster and configures the Admin Tools to work with the larger cluster.

Once you have added one or more hosts to the cluster, you can add them as nodes to the database. This can be accomplished using either the Management Console interface or the Administration Tools interface or alternatively the admintools command line (to preserve the specific order of the nodes you add). As adding nodes in the MC is GUI driven and thus very straightforward, the following process outlines how to use Administration Tools instead.

  • Open the Administration Tools.
  • One the Main Menu, select View Database Cluster State to verify that the database is running. If it is not, start it.
  • From the Main Menu, select Advanced Tools Menu and click OK.
  • In the Advanced Menu, select Cluster Management and click OK.
  • In the Cluster Management menu, select Add Host(s) and click OK.
  • Select the database to which you want to add or remove hosts, and then select OK. A list of unused hosts is displayed.
  • Select the hosts you want to add to the database and click OK
  • When prompted, click Yes to confirm that you want to add the hosts.
  • When prompted, enter the password for the database and then select OK.
  • When prompted that the hosts were successfully added, select OK.
  • Vertica now automatically starts the rebalancing process to populate the new node with data. When prompted, enter the path to a temporary directory that the Database Designer can use to rebalance the data in the database and select OK.
  • Either press enter to accept the default K-safety value, or enter a new higher value for the database and select OK.
  • Select whether Vertica should immediately start rebalancing the database, or whether it should create a script to rebalance the database later.
  • Review the summary of the rebalancing process and select Proceed.
  • If you chose to automatically rebalance, the rebalance process runs. If you chose to create a script, the script is generated and saved. In either case, you are shown a success screen, and prompted to select OK to end the Add Node process.

Since this demo uses three hosts (maximum allowed to kick some tires and try Vertica without an enterprise license), once configured and set up, this is how the cluster looks like in the management console (database and hosts views).

Aside from the Management Console interface, various parts of Vertica database can be administered and monitored via the system tables and log files. Vertica provides an API (application programming interface) for monitoring various features and functions within a database in the form of system tables. These tables provide a robust, stable set of views that let you monitor information about your system’s resources, background processes, workload, and performance, allowing you to more efficiently profile, diagnose, and view historical data equivalent to load streams, query profiles, tuple mover operations, and more. Because Vertica collects and retains this information automatically, you don’t have to manually set anything. You can write queries against system tables with full SELECT support the same way you perform query operations on base and temporary tables. You can query system tables using expressions, predicates, aggregates, analytics, subqueries, and joins. You can also save system table query results into a user table for future analysis.

System tables are grouped into the following schemas:

  • V_CATALOG – information about persistent objects in the catalog
  • V_MONITOR – information about transient system state

These schemas reside in the default search path so there is no need to specify schema.table in your queries unless you change the search path to exclude V_MONITOR or V_CATALOG or both. Most of the tables are grouped into the following areas:

  • System Information
  • System resources
  • Background processes
  • Workload and performance

The following two queries outline metadata information for two tables – databases and cpu_usage – from their respective v_catalog and v_monitor schemas.

Vertica also collects and logs various system events which can help in troubleshooting and general system performance. The events are collected in the following ways.

  • In the Vertica.log file
  • In the ACTIVE_EVENTS system table
  • Using SNMP
  • Using Syslog

This concludes Vertica installation process. Even though I came across a few issues, those were mainly specific to the hardware configuration I used for this demo and in a ‘real-world scenario’ Vertica installation process is usually trouble-free and can be accomplished in less then 30min. In the next post I will go through the data used for the TPC-DS benchmark testing, loading mechanism, some of the performance considerations imposed by its volume and hardware specifications used and provide an overview of the results of the first ten queries I run. For the remaining ten queries’ results as well as PowerBI and Tableau interactions please see the final instalment to this series – post 4 HERE.

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