Pratica di Shadowing: How to Create Gold, Silver, and Bronze Tables in Postgres for a Medallion Data Architecture! - Impara a parlare inglese con i video
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Hey guys, DataGuy here, and today I have a video for you that has been requested for a long time, which is how you can set up bronze,
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silver, and gold medallion tables within Postgres.
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And don't worry if you're not using Postgres, the same patterns will apply for really any kind of SQL database,
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you're just going to need to alter some of the syntax for your specific database.
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And what I'm using here to run it is just Postgres app for MacBooks, you can download it online super easy
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and then i'm going to be just connecting
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and running my scripts within dbeaver just local ui for actually running actions within a database and
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so what i'm going to actually also want to be using
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as the data set for this is just the classic taxi
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vendor data set you can download it really anywhere online just
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search for taxi vendor data set it's the most classic nyc
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taxi kind of pattern for running these kind of operations and examples.
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And so without further ado, let's get into it and start creating our bronze schema.
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And so the first thing you're going to need to do is obviously just create your schema.
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If it doesn't exist, create bronze, and then drop any existing bronze table if it already exists and it doesn't already exist.
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So you're going to see that error message there at start.
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And then assuming that that hasn't been created right
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so we just want to create a fresh table of any new data
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so any pre -existing data that was already around don't want it anymore
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so now we're going to create this blank table it doesn't exist
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and then on the we're going to also create an index on the load timestamp for more efficient querying
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so instead of just using timestamp to kind of order our
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data we want to create an index make it easier and more organized to actually just query our raw data downstream.
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So we're not stuck always just having to use that timestamp or use that raw timestamp as our identifying index.
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And this also going to help queries run faster as well.
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Then what we'll do is insert some sample data into our bronze layer.
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So this would likely just be something you're going to be doing, you know, either as part of your data ingestion.
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I'm only doing it here because I don't have any, you know, I just don't want to bother going to the process of uploading data from an external database, right?
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So I'm just going to kind of create an example.
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And this is again, just data that copied over from that taxi trip data set.
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So you can download and use and basically just copy that in yourself as well.
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And then once we're done with that, we're also going to, you'll notice here, I added some data that does have data quality issues within the silver layer,
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we're actually going to clean this data out.
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So I'm going to show you how you clean your data as part of this process.
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So we have one entry that has a negative fare and then one entry that actually has some invalid coordinates.
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I just took an entry and adjusted to break it.
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So then once we have run that insert command, we've got our data loaded up.
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The next step is going to just be running a quick verify bronze data layer load.
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So, you know, just making sure every time this script gets run
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that our data is of the expected size and
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so here we just have a simple select statement hey count all as total records from bronze taxi trips raw
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and then just sample the first five rows to make sure
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the data isn't corrupted it's of the expected you know type
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and look and feel that that we're anticipating here
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so this is our first step so just creating that bronze table
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and so you'll see we'll run this script
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and now we just have our first kind of five rows of this taxi data within our database, right?
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So here we go to tables.
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Now we will see our taxi table.
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So here have taxi trips raw.
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And then next, what we'll do is start building our silver table.
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So here we'll add a new silver, a new script.
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So new SQL script here, and this will be our silver SQL script.
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And so next we're going to do is within silver layer, typically, you want take hey we've got our raw data in
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the ingestion layer now we want to clean it do some validation
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standardization so that it is you know it's not fully transformed for analytics
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but we've gotten you know all the bad data we have in a really easily transformable format
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and so first thing we're going to do here is same thing just creating the schemas
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if they don't already exist so creating silver schema dropping an existing table
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so taxi trips cleaned
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and then what we're going to do here is create a new table with all the different fields
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that we want to track in our silver stage
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so here we're just creating a surrogate key
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so serial number trip trip ID and for easier joins
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and this is how you know imagine is an ID you'd be using to join with other pieces of data
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and we also are creating some metadata fields
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so timestamp for bronze load silver loads we can see the Delta between bronze
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and silver the actual source file the raw source file
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so you can trip for traceability then just create a nice clean shrimp trip information with the proper data types, location data with precision for GPS coordinates,
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trip details, also starting to calculate things like financial data, and then also data quality flags.
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So this is how we're going to filter bad data downstream to make sure, you know, you don't want to delete bad data, but you want to kind of quarantine it.
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And then we also have some fields
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that we're going to calculate like the trip duration in minutes and the trip speed in mile per hour as well.
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So once we've created the table, the next thing we're going to do is also create some index for common query patterns.
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So these will make it easier to find the data for, you know, these particular values.
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So, you know, for things like, hey, pick up date time, the amount of silver taxi trips that are, you know, running at a certain pickup or drop off time,
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the vendor IDs, you can track trips by vendor, payment types, you can track by payment type, valid trips, so you can filter out any invalid trips or any invalid data.
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And let me just create a few of two rows here for spacing.
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And then after we've done, we're done creating the indexes, then we're just going to run a very long insert command
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to insert all of our different data into this new table we just created.
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So here we have insert into, go up here into silver taxi trips, all those fields we just created
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and then selecting from our bronze table source file casting the
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vendor id changing the integer types to the proper integer types changing cases to make sure that they're
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capped at hey you can't have passengers less than one
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because you don't have a ride if you don't have a passenger
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and you can't have more than six
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because we don't have let's say larger vans in our fleets we know
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that legally you're never allowed to have more than six
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and then these are just again casting different variables to the correct type
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and then same thing here casting valid coordinates making sure they're within the new york city approximate bounds
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so testing the coordinates for whether they're actually taking place in new york city also running fair validation
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so making sure the fair is actually greater than zero for
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each each entry duration has to be between one hour
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and three minutes you can't have a ride less than a minute
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and we don't allow rides more than three hours obviously you can change
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that then we're also calculating the trim duration in minutes
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so just basically here subtracting the drop -off time minus the pickup time
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and just getting a value in numbers or in you know minutes
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and then finally calculating the average speed distance over time in mile per hour
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so we have some clean data rather than just raw you know entries
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and makes it easier for obviously querying this all downstream
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because you don't care about pickup
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and drop off time mostly most likely you care about how long were these trips taking
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and then also just doing some basic not null checks to make sure
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that hey drop off is always after pickup
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and also there has to be a pickup
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and a drop off you obviously can't have one in the other
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so once we've done that we've inserted all our data
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and done some transformations in the process we're then also going to perform some data validation
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or create a data quality table to create summaries from some data quality checks we'll run on this table.
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So here we're creating, we're saying, hey, making sure every field has valid coordinates, valid fares, valid durations, has fully valid records.
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So it has all those things as valid.
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And then also the quality percentage.
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So saying, hey, total amount of times when we don't actually have quality rides versus quality rides, so you can get an overall view of how well -maintained and how well -recorded your data is.
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And then just saving in an external table for easier analysis and validation.
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It also makes it easier if you're collecting data over time, right?
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You can have each entry in this table be the sum data, sum validation of each time you ingested that data.
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Then what we'll do is just show the data quality report.
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So just add a select statement here.
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And then also show another sample of our clean data.
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Just showing that it is, in fact, cleaned.
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And boom, that is our silver stage, all nice and complete
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so now it's time to move on to gold and
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so here again we can see some of the output here of our top fields within our now silver table
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so has valid coordinates valid fair making sure this is all valid data
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so cool now creating our next
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and final sql script we are then going to create our gold table
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so here let's go and this is the table
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that is going to be you know really tightly design business -ready aggregations analytics.
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So we're really taking high -level metrics, analytics, and doing a lot of calculations here that will be used in downstream business processes and reporting.
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So first what we'll do is just do our classic, hey, create a schema if it doesn't exist.
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So creating that gold table schema.
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Then we're going to drop it if it doesn't exist and create a new table.
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um with a select statement so here what we'll do is drop table
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if it doesn't exist the daily trip summary table
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and then create gold daily trip summary as selecting pickup date
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time from as trip date the total number of trips by
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counting all the number of trips um count distinct vendor ids as active vendors
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so only counting distinct vendors
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so duplicating vendors you know exactly how many you know drivers you have um also passenger metrics here
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so the passenger count for total passengers average passengers per trip
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averaging the total distance trip duration trip distance speed also creating
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a lot of these average financial metrics like average total fare
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amount total tips total revenue average trip cost the max trip cost tip analysis for tip percentage
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and average tip
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and then also data quality metrics analyzing you know at a
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high level hey are a lot of these trips uh valid
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and you're seeing pulling all this data from that silver table
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and grouping it by date time ordered by trip date which is again that index we created at the start
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now then what we're going to do is create another index for date based queries
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so we're here we're going to create index daily date based on daily trip summary
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and then we're going to do some analysis on vendor performance metrics
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so this is very typical in a gold table you know
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you're going to want to perform analysis some of these queries
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so here what we're doing is you know basically same thing we did up there dropping vendor performance
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that already doesn't know if it already exists and then here creating a new table where we're actually assigning our vendors
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names so here we have you know create a mobile verifone else's other
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and we're also you know making the data a lot cleaner
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to look at instead of just you know vendor ids calculating
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some of these things like volume metrics the amount of total trips stays active per vendor average trips per day per vendor.
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And, you know, basically all that same kind of average, all those averages we counted at the start, but now broken down per vendor.
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And that's really a lot of what gold tables are doing.
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It's taking the same information, but slicing it in different ways that analysts might use, right?
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So understanding, hey, what, you know, vendors using more cash versus credit card or what vendors are getting the most tips, understanding all of these processes.
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And then another one, it could be something like payment type analysis.
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So let's say you want to understand, you know, what type of payments people are using and how that has input, you know, affects the number of trips or the tips you're getting, right?
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So here we have credit card, cash, no charge or dispute.
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And here what we can do is start tracking, hey, people that are paying cash, what's their average trip distance?
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What's their total revenue?
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And tip analysis, I'd say is most relevant here for credit versus cash is saying, hey, how much do I normally get tipped when people pay with cash versus credit?
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And then maybe, you know, you want to say, hey, I want to actually only, you know, accept cash or credit if I expect,
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if one is giving vastly larger tips than the other, right?
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And so I could really go on for days with all the different types of analysis you could do here, but I'll cap it off as,
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you know, another one for, hey, trip distance duration.
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So here, you know, let's say I want to, or, you know, analyze, hey, what is the hourly demand patterns right so here you know
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if i want to look at what is you know i
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want to say hey more people need to be on the road at a certain time understanding hour by hour
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when are people most likely to you know create to schedule rides to book rides
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and you can group them in these different periods
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and then analyze you know schedule your drivers accordingly
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so you don't have extra drivers on the road just sitting idle
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when you could be having them sit home and and then also So, you know, something like a trip distance duration is also a great one to have.
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So just, you know, really simple, hey, understanding different categories of trip distances.
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So if you want to analyze costs and tips on that as well, you can.
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And then another very common thing to do after you've, you know, created your tables is also create views, right?
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And so these are basically, you know, windows within SQL that you can use to say, hey, this is an executive dashboard that's going to sum up today's metrics,
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with the manner of trips today, revenue today, trips yesterday, revenue yesterday to compare, week to date, month to date.
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And this is, you know, really a executive level view ready to be sent out to
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an external party where it just has only the relevant information that's gone through these series of cleaning, validation, calculation to arrive at these actual data points.
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And that's, again, the purpose of a gold table.
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And then similarly, you create something like a data quality monitor, right?
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Where here, we're creating a monitor where we're selecting,
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you know hey bronze layer validation silver layer validation gold layer validation having all their data quality percentages added there
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so you can actually see hey these are you know this is how data is evolving
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and being cleaned and changing as it flows through our systems and
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that is really everything i have for you today you know
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i wanted to make this video i thought it was something
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that been getting requested enough that i finally had to get around to it
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so it took some time so i hope you enjoyed this video.
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I hope you got some value out of it.
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I hope you have a great rest of your day.
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Data Guy out.
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Vocabolario e note di pronuncia per questa lezione
Questo video contiene 202 frasi e 2901 parole da ripetere con lo shadowing. Il parlato dura 15:04. Chi parla va veloce, circa 193 parole al minuto: aspettati suoni legati e ridotti. Il 85% delle parole rientra nelle 3.000 più comuni dell’inglese; conviene studiare le altre prima di iniziare.
Vocaboli chiave di questo video
15 parole del video che vale la pena imparare, con pronuncia e significato:
| Parola | Pronuncia | Significato |
|---|---|---|
| vendor sostantivo | /ˈvɛn.dɚ/ | venditore, venditrice |
| bronze sostantivo | /bɹɑnz/ | bronzo |
| valid aggettivo | /ˈvælɪd/ | valido |
| taxi sostantivo | /ˈtæksi/ | taxi, tassì |
| validation sostantivo | /ˌvæl.əˈdeɪ.ʃən/ | validazione |
| layer sostantivo | /ˈleɪ̯ɚ/ | strato |
| script sostantivo | /skɹɪpt/ | scritto |
| duration sostantivo | /dʒʊˈɹeɪ.ʃən/ | durata |
| metric aggettivo | /ˈmɛt.ɹɪk/ | metrico |
| query sostantivo | /ˈkwɪɹ.i/ | interrogativo, domanda |
| select verbo | /sɪˈlɛkt/ | scegliere, selezionare |
| passenger sostantivo | /ˈpæs.ɪn.d͡ʒɚ/ | passeggero, passeggera |
| insert verbo | /ɪnˈsɝt/ | inserire |
| coordinate verbo | /koʊˈɔɹ.dəˌneɪt/ | coordinare, accordarsi |
| database sostantivo | /ˈdeɪtəˌbeɪs/ | database, base di dati |
I phrasal verb che sentirai
| Parola | Pronuncia | Significato |
|---|---|---|
| drop off verbo | addormentarsi, appisolarsi | |
| go through verbo | attraversare | |
| go up verbo | salire | |
| pick up verbo | tirare su, sollevare | |
| set up verbo | /ˌsɛt ˈʌp/ | preparare, installare |
La grammatica di questo video
Le strutture che chi parla usa di più, con le parole esatte del video:
| Struttura | Nel video |
|---|---|
| Present perfect have/has + participio passato — un’azione passata che conta ancora adesso | has been requested · hasn't been created · have run |
| Forma passiva be + participio passato — conta ciò che accade, non chi lo fa | has been requested · been created · isn't corrupted |
| Frasi relative who / which + frase — un’informazione in più su una persona o una cosa | time, which is · date which is |
Pronuncia a cui fare attenzione
Chi parla usa 97 contrazioni e forme ridotte, come we're, don't, you're. Pronunciale nella forma breve, così come le senti.
- I suoni “sh” e “zh”: validation /ˌvæl.əˈdeɪ.ʃən/, duration /dʒʊˈɹeɪ.ʃən/, calculation /ˌkælkjuˈleɪʃn̩/, efficient /ɪˈfɪʃənt/, transformation /ˌtɹæns.fɔɹˈmeɪ.ʃən/
- Parole lunghe — attenzione all’accento: validation /ˌvæl.əˈdeɪ.ʃən/, coordinate /koʊˈɔɹ.dəˌneɪt/, analytics /ˌæn.əˈlɪt.ɪks/, similarly /ˈsɪm.ə.lə.li/, transformation /ˌtɹæns.fɔɹˈmeɪ.ʃən/
Come esercitarsi con questo video
- Ascolta tutto il video una volta senza parlare e annota le parole che non conosci.
- Inizia a velocità 0,75×, fai shadowing frase per frase e torna alla velocità normale quando diventa facile.
- Registrati e confronta con l’originale, facendo attenzione a parole come vendor, bronze, valid.
Cos'è la tecnica dello Shadowing?
Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.